Multisystem Processes & Disorders

Protein-calorie malnutrition: outpatient and inpatient assessment

Clinical Overview and When to Suspect Protein-Calorie Malnutrition

— Starvation-related (anorexia nervosa, social food insecurity, chronic dysphagia): pure caloric deficit without inflammation

— Chronic disease-related (CHF, COPD, CKD, cirrhosis, cancer cachexia, RA): mild–moderate inflammation drives proteolysis

— Acute disease/injury-related (sepsis, major trauma, burns, severe pancreatitis): marked inflammation, rapid lean mass loss

— Unintentional weight loss ≥5% in 1 month, ≥7.5% in 3 months, or ≥10% in 6 months

— Elderly with BMI <22, sarcopenia, or "failure to thrive"

— Chronic GI disease (IBD, celiac, chronic pancreatitis, post-bariatric), HIV, malignancy, dementia, alcohol use disorder

— Food-insecure households, homebound seniors, polypharmacy with anorexia

— NPO >5–7 days, prolonged ICU stay, mechanical ventilation

— Pressure injuries, poor wound healing, recurrent infections

— Refeeding-prone admissions: alcohol use disorder, anorexia nervosa, prolonged fasting, post-bariatric, cancer

Board pearl: Albumin and prealbumin are markers of inflammation, not nutrition. A low albumin in a sick inpatient reflects the acute-phase response; do not "diagnose malnutrition" from albumin alone — use GLIM or ASPEN/AND phenotypic + etiologic criteria (weight loss, low BMI, reduced muscle mass + reduced intake or disease burden).

Step 3 management: On every admission and at every annual visit for at-risk adults, document weight trajectory, oral intake, and functional status — this triggers dietitian consult and reimbursable MNT (medical nutrition therapy) under Medicare Part B for diabetes and CKD.

Protein-calorie malnutrition (PCM) is a state of inadequate macronutrient intake, absorption, or utilization relative to metabolic demand, producing measurable changes in body composition, function, and outcomes.

Three pathophysiologic categories (AND/ASPEN consensus):

When to suspect in outpatient:

When to suspect in inpatient:

USPSTF/Step 3 framing: routine malnutrition screening is recommended for hospitalized patients within 24 hours of admission (Joint Commission standard) using a validated tool (MST, MUST, NRS-2002).

Presentation Patterns and Key History

— Dietary: 24-hour recall, meals/day, who shops/cooks, food insecurity screen ("Hunger Vital Sign" — 2 questions, validated)

— Weight trajectory: ask for a specific number and timeframe; "my pants are looser" or belt notches

— Functional: grip strength, stair climbing, ADLs/IADLs, gait speed (<0.8 m/s suggests sarcopenia)

— GI: dysphagia, early satiety, nausea, diarrhea, steatorrhea, dental status, taste changes

— Psychosocial: depression (PHQ-9), cognitive impairment, isolation, alcohol use (AUDIT-C), poverty

— Medication review: anorexigenic drugs — metformin, SSRIs, opioids, digoxin, methylphenidate, topiramate, GLP-1 agonists, chemotherapy, polypharmacy

— Disease burden: cancer, CHF, COPD, CKD, cirrhosis, HIV, IBD, hyperthyroidism, adrenal insufficiency

— Weight loss + night sweats + lymphadenopathy → lymphoma/TB

— Weight loss + polyuria/polydipsia → uncontrolled diabetes

— Weight loss + heat intolerance + tremor → hyperthyroidism

— Weight loss + diarrhea + dermatitis → celiac, IBD, carcinoid

— Weight loss + smoker + hemoptysis → lung cancer

Key distinction: Cachexia ≠ simple malnutrition. Cachexia requires underlying disease + inflammatory drive + involuntary weight loss ≥5% and is not fully reversible by feeding alone — treatment must address the underlying illness. Sarcopenia is age-related muscle loss; pure starvation is reversible with refeeding.

Board pearl: A geriatric patient with "failure to thrive" needs a structured workup: depression, dementia, dysphagia, dentition, drugs, and disease — the "5 Ds" — before labeling idiopathic.

Adult kwashiorkor-like (rare in US, seen in critical illness/cirrhosis): hypoalbuminemia, edema, fatty liver, preserved or increased weight from third-spacing — masks underlying lean mass loss.

Adult marasmus-like: visible wasting, low BMI, preserved albumin early, sarcopenia, temporal/interosseous wasting — classic in cancer cachexia, COPD, dementia.

Mixed/Marasmic-kwashiorkor: most common hospital phenotype — chronic wasting plus acute inflammatory insult (e.g., elderly nursing home patient admitted with sepsis).

Key history domains (Step 3 ambulatory voice):

Red-flag pairings:

Physical Exam Findings and Functional Assessment

— Temporal wasting, hollowed supraclavicular fossae, prominent zygomatic arches

— Interosseous muscle wasting of hands (look between thumb and index)

— Quadriceps and gastrocnemius atrophy; "tenting" of skin over clavicle

— Loose-fitting dentures or clothing — corroborates weight loss history

— BMI: <18.5 underweight; <16 severe; in elderly, <22 carries mortality risk

— Mid-upper arm circumference (MUAC): <22 cm in women, <23 cm in men suggests malnutrition; useful when weight unobtainable (bedbound, amputee, edema)

— Calf circumference: <31 cm suggests sarcopenia

— Triceps skinfold: subcutaneous fat reserve

— Hand grip dynamometry: <27 kg men, <16 kg women → low strength

— Gait speed <0.8 m/s, 5-times sit-to-stand >15 sec

— SARC-F questionnaire for sarcopenia screening

— Bitemporal hair thinning, easy pluckability, lanugo (anorexia nervosa)

— Angular cheilitis, glossitis → B-vitamin/iron deficiency

— Koilonychia → iron; spoon nails, Beau's lines from prior catabolic insult

— Petechiae, perifollicular hemorrhage → vitamin C

— Bitot spots, night blindness → vitamin A

— Dermatitis on sun-exposed areas → niacin (pellagra)

— Edema with normal cardiac/renal exam → hypoalbuminemic edema

— Bradycardia, hypothermia, hypotension — severe malnutrition/anorexia nervosa; admission threshold (HR <50, T <36, SBP <90, orthostatic drop)

— Bradycardia + amenorrhea + low BMI → anorexia nervosa admission criteria

CCS pearl: In an inpatient CCS case of severe malnutrition, order standing and supine vitals, daily weights, telemetry, and a phosphorus/magnesium/potassium panel before initiating feeds — and consult nutrition on day 1.

Board pearl: Edema in a malnourished patient with normal JVP and clear lungs = hypoalbuminemic edema; don't reflexively diurese.

General inspection:

Anthropometrics (document at every visit):

Functional measures (GLIM "reduced muscle mass" surrogate):

Skin, hair, nails, mucosa (micronutrient clues often coexist):

Hemodynamic and vital sign clues:

Diagnostic Workup — Initial Labs and Screening Tools

— MST (Malnutrition Screening Tool): 2 questions, score ≥2 → refer dietitian — preferred for hospital and ambulatory

— MUST: community/long-term care

— NRS-2002: European hospital standard, integrates disease severity

— MNA-SF: validated in adults ≥65, six items — gold standard in geriatrics

— GLIM (Global Leadership Initiative on Malnutrition) — current consensus: requires ≥1 phenotypic (weight loss, low BMI, reduced muscle mass) + ≥1 etiologic (reduced intake/assimilation OR inflammation/disease burden)

— ASPEN/AND adult criteria: needs 2 of 6 — insufficient intake, weight loss, loss of muscle mass, loss of subcutaneous fat, fluid accumulation, reduced grip strength

— CBC: anemia (iron, B12, folate, chronic disease), lymphopenia (<1500 in moderate, <900 severe — nonspecific)

— CMP: glucose (hypoglycemia in severe starvation), BUN/Cr (BUN low in protein deficiency), LFTs, albumin (inflammation marker), electrolytes

— Phosphorus, magnesium, potassium, ionized calcium — mandatory before refeeding

— Prealbumin (transthyretin): half-life ~2 days, trends nutrition response but also acute-phase reactant; don't use as sole marker

— CRP: distinguishes inflammatory etiology; high CRP + low albumin = disease-related malnutrition

— TSH, HbA1c, HIV, B12, 25-OH vitamin D, iron studies, ferritin

— Vitamin levels when indicated: thiamine (alcohol, bariatric, hyperemesis), vitamin A/E/K (fat malabsorption), zinc (poor wound healing), copper (post-bariatric, zinc supplementation)

Key distinction: Albumin reflects inflammation; weight, intake, and muscle mass reflect nutrition. A normal albumin does not rule out malnutrition, and a low albumin does not confirm it.

Board pearl: Always check phosphorus, magnesium, and potassium before feeding a severely malnourished patient. Hypophosphatemia is the cardinal lab finding of refeeding syndrome and can be fatal within 72 hours of refeeding initiation.

Validated screening tools (choose by setting):

Diagnostic frameworks:

Initial labs (target the question, don't shotgun):

Targeted GI workup if malabsorption suspected: stool fecal fat, fecal elastase, tTG-IgA + total IgA, stool calprotectin

Diagnostic Workup — Body Composition and Confirmatory Studies

— DEXA: gold standard for lean mass, fat mass, bone density — appendicular lean mass index <7.0 kg/m² (men), <5.5 (women) = sarcopenia

— Bioelectrical impedance analysis (BIA): bedside, affected by hydration — useful for trends

— CT-based muscle assessment: L3 skeletal muscle index from existing oncology CTs is increasingly used for sarcopenic obesity in cancer

— Ultrasound of quadriceps thickness: emerging ICU tool to track muscle loss

— Measured REE (resting energy expenditure) via VO₂/VCO₂

— Indicated in ICU patients with obesity, prolonged ventilation, failure to wean, persistent malnutrition despite predicted-equation feeding

— Predictive equations (Harris-Benedict, Mifflin-St Jeor, Penn State for vented patients) are acceptable when calorimetry unavailable

— Age-appropriate cancer screening up to date (colonoscopy, mammography, Pap, low-dose chest CT in smokers)

— CT chest/abdomen/pelvis only if directed by symptoms/exam — yield of "shotgun" imaging is low

— Stepwise: H&P → labs (CBC, CMP, TSH, HIV, HbA1c, CRP, UA, FOBT, CXR) → directed imaging

— Up to 25% of involuntary weight loss in elderly remains idiopathic after thorough evaluation — these patients still warrant 3–6 month follow-up

— Major: BMI <16, weight loss >15% in 3–6 months, little/no intake >10 days, low pre-feeding K/Mg/PO₄

— Minor: BMI <18.5, weight loss >10% in 3–6 months, little/no intake >5 days, alcohol/insulin/chemo/diuretic history

Step 3 management: In unexplained weight loss, ensure age-appropriate cancer screening is current before ordering expensive imaging — boards reward stewardship and adherence to USPSTF over reflexive pan-CT.

Board pearl: A cancer patient with low muscle mass on routine L3 CT slice has higher chemotherapy toxicity and worse survival — sarcopenia is a stratifier even in obese patients.

Body composition assessment (when needed for diagnosis or research):

Indirect calorimetry (metabolic cart):

Workup of unexplained weight loss (involuntary ≥5% in 6–12 months without clear cause):

Confirming refeeding risk (NICE criteria, ≥1 major or ≥2 minor):

Severity Stratification and Management Logic

— Severe (acute illness): weight loss >2% in 1 wk, energy intake ≤50% of needs >5 days, severe muscle/fat loss, severe fluid accumulation, grip strength <P10

— Moderate: weight loss 1–2% in 1 wk, intake <75% for ≥7 days, mild–moderate muscle/fat loss

— Oral first if safe swallow + can meet ≥60–75% of needs — fortified diet, oral nutrition supplements (ONS) between meals

— Enteral (EN) if gut works but intake inadequate >7–14 days or anticipated NPO >7 days — NG for short-term, PEG/J for >4 weeks

— Parenteral (PN) only if gut nonfunctional, inaccessible, or perforated — peripheral PN <2 wks; central (TPN) for longer/concentrated

— "If the gut works, use it" — EN reduces infection vs PN

— Energy: 25–30 kcal/kg/day (use IBW if BMI >30; permissive underfeeding 11–14 kcal/kg actual for obese ICU)

— Protein: 1.2–1.5 g/kg/day in acutely ill; 1.5–2.0 g/kg in burns, trauma, wounds, CRRT; 0.8 in stable chronic; reduce to 0.6–0.8 only in advanced CKD not on dialysis

— Severely malnourished/refeeding risk: start 10 kcal/kg/day (5 kcal/kg in BMI <14 or >15 days fasting), advance over 4–7 days

— Critically ill: start EN within 24–48 hours of ICU admission if hemodynamically stable

— Non-ICU: initiate within 7 days if oral intake inadequate

CCS pearl: In the CCS interface, after diagnosing severe malnutrition, the order set is: NPO → dietitian consult → daily weights, strict I/O → CBC, CMP, Mg, Phos → thiamine 100 mg IV before dextrose → multivitamin → start enteral feeds at 10 kcal/kg → repeat electrolytes q12h × 72h.

Board pearl: Always give thiamine before glucose in any severely malnourished or alcohol-use patient to prevent Wernicke encephalopathy.

Severity by AND/ASPEN (use 2 of 6 criteria, graded as moderate vs severe in acute/chronic illness or social context):

Decision tree — route of nutrition (ASPEN hierarchy):

Caloric and protein targets (start point):

Inpatient timing:

Pharmacotherapy and Nutritional Prescribing — First-Line Regimen

— Standard polymeric formulas (Ensure, Boost): 1.0–1.5 kcal/mL, balanced macros — first-line for ambulatory PCM, prescribe 2–3 × 240 mL between meals (not with meals — suppresses appetite)

— Disease-specific: diabetes (Glucerna), renal (Nepro — low K/Phos), pulmonary (Pulmocare — higher fat to reduce CO₂ — limited evidence)

— Meta-analysis: ONS in malnourished hospitalized adults reduces mortality and readmissions (EFFORT trial)

— Polymeric (intact protein): first-line for functional gut

— Semi-elemental/elemental: short bowel, severe pancreatitis, malabsorption — peptides, MCT

— Immunonutrition (arginine, glutamine, omega-3, nucleotides): consider in elective major surgery (head/neck, GI cancer) 5–7 days pre-op — improves infection outcomes per ASPEN/SCCM

— Dextrose (≤4–5 mg/kg/min to avoid hyperglycemia, hepatic steatosis)

— Amino acids 1.2–2.0 g/kg

— Lipid emulsion (smof or soy/MCT/olive/fish blend preferred over pure soy to reduce PNALD)

— Standard electrolytes, multivitamin, trace elements daily

— Insulin as needed (target glucose 140–180 mg/dL)

— Thiamine 100–300 mg IV/PO daily × 3–5 days (or longer for alcohol use)

— Multivitamin daily

— Repleted phosphorus, magnesium, potassium aggressively

— Vitamin D, iron, B12, zinc per labs

— Mirtazapine 7.5–15 mg qhs — preferred in depressed elderly with weight loss; sedating and orexigenic via H1/5-HT₂

— Megestrol acetate — modest weight gain (mostly fat/fluid), risk of VTE, adrenal suppression — avoid in elderly, frail

— Dronabinol — HIV/cancer cachexia; sedation, dysphoria in elderly

— Corticosteroids — short-term in cancer cachexia palliation only; catabolic with chronic use

— Avoid cyproheptadine in elderly (anticholinergic, Beers)

Step 3 management: Outpatient elderly weight loss with depression: try mirtazapine plus structured ONS and dietitian referral before reaching for megestrol — addresses both mood and appetite with one well-tolerated drug.

Oral nutrition supplements (ONS):

Enteral formulas:

Parenteral nutrition components (central TPN):

Micronutrient repletion before/during refeeding:

Appetite stimulants (weak Step 3 evidence — know but use selectively):

Procedures and Advanced Nutrition Delivery

— Nasogastric (NG) tube: anticipated EN <4 weeks; bedside placement; confirm by post-placement abdominal X-ray (auscultation is not adequate)

— Nasojejunal (NJ): high aspiration risk, gastroparesis, severe pancreatitis (post-ligament of Treitz reduces pancreatic stimulation)

— PEG: anticipated EN >4 weeks (stroke with persistent dysphagia, ALS, dementia — caveats below, head/neck cancer)

— PEG-J or surgical jejunostomy: chronic gastroparesis, gastric outlet obstruction, post-Whipple

— Active peritonitis, uncorrected coagulopathy (INR >1.5, plt <50K)

— Massive ascites, gastric varices, prior gastric surgery (relative)

— Advanced dementia: PEG does not improve survival, aspiration, pressure injuries, or comfort — careful goals-of-care discussion required; hand feeding is preferred

— Antibiotic prophylaxis (cefazolin) given before placement

— PICC for ≤weeks–months; tunneled catheter (Hickman, Broviac) or port for long-term home PN

— Tip must be at cavoatrial junction — confirm by CXR

— Strict sterile technique, dedicated lumen, CLABSI bundle

— Identify high risk (NICE criteria)

— Start at 5–10 kcal/kg/day, advance by 25–33% q1–2 days over 5–7 days to goal

— Thiamine 200–300 mg IV daily × 5–7 days before any dextrose

— Replete K, Mg, PO₄ to upper-normal before initiating feeds, then monitor q12h × 72h

— Watch for cardiac arrhythmia, CHF, respiratory failure, rhabdomyolysis, hemolysis, seizures

— Cardiac monitoring, fluid restriction (avoid CHF), gradual caloric advancement

— "Start low, go slow, watch the phos"

CCS pearl: For a CCS patient with stroke and persistent dysphagia at hospital day 14, advance from NG feeding to PEG placement after speech-swallow evaluation confirms unsafe oral intake — and document goals-of-care conversation with family.

Board pearl: In acute pancreatitis, early enteral feeding within 24–72 h via NJ or NG beats NPO/TPN — reduces infection and mortality.

Enteral access selection:

PEG placement contraindications/cautions:

Central venous access for PN:

Refeeding syndrome management:

Severe anorexia nervosa inpatient refeeding:

Special Populations — Elderly and Renal/Hepatic Impairment

— Prevalence: 5–10% community, 20–40% hospitalized, 30–50% long-term care

— Use MNA-SF at every Medicare Annual Wellness Visit

— Address the "Meals on Wheels" mnemonic: Medications, Emotional (depression), Anorexia/Alcohol/Abuse, Late-life paranoia, Swallowing, Oral/Dental, No money, Wandering (dementia), Hyperthyroidism, Enteric (malabsorption), Eating problems, Low-salt/low-cholesterol diets (over-restriction), Shopping/cooking problems

— Liberalize restrictive diets in frail elderly — strict cardiac/diabetic/renal diets in nursing home residents cause anorexia and weight loss; AHA and ADA both endorse liberalization for QOL

— Target protein 1.0–1.2 g/kg/day (not 0.8) + resistance exercise twice weekly + vitamin D repletion

— Leucine-enriched supplements may help

— Protein 0.6–0.8 g/kg/day to slow progression; ensure adequate calories 30–35 kcal/kg

— Once on dialysis, increase to 1.2 g/kg HD, 1.2–1.3 g/kg PD to compensate for losses

— Monitor for protein-energy wasting (PEW) — independent mortality predictor in dialysis; serum albumin <3.8, weight loss, low SGA score

— Phosphorus and potassium-restricted formulas (Nepro, Suplena)

— Reverse old teaching: DO NOT restrict protein — increases hepatic encephalopathy and worsens sarcopenia

— 1.2–1.5 g/kg/day protein, 35–40 kcal/kg/day, late-evening snack (50 g carb + protein) to prevent overnight catabolism

— BCAA supplementation may help refractory HE

— Sarcopenia is a strong predictor of post-transplant mortality

Key distinction: Pre-dialysis CKD = restrict protein modestly to slow progression. Dialysis-dependent CKD = liberalize protein because of dialytic losses. Cirrhosis = high protein regardless of encephalopathy.

Board pearl: In a nursing home resident losing weight on a "cardiac/renal/diabetic diet," liberalize the diet first — it's often the highest-yield intervention.

Elderly outpatient malnutrition:

Sarcopenia in older adults:

CKD (non-dialysis, stages 3b–5):

Cirrhosis:

Hepatic encephalopathy with malnutrition: treat HE (lactulose, rifaximin) — do not lower protein.

Special Populations — Pregnancy, Pediatrics, Bariatric, and Eating Disorders

— Energy: add +340 kcal/day T2, +450 kcal/day T3; protein 1.1 g/kg

— Weight gain targets (IOM): 28–40 lb (underweight BMI <18.5), 25–35 lb (normal), 15–25 lb (overweight), 11–20 lb (obese)

— Hyperemesis gravidarum: rehydration + thiamine before dextrose to prevent Wernicke; if persistent inability to maintain weight, enteral feeding before TPN

— Folate 400–800 µg preconception; iron 27 mg/day; iodine 150 µg

— Weight-for-height z-score, BMI-for-age z-score, MUAC

— Mild (z −1 to −1.9), moderate (−2 to −2.9), severe (≤−3)

— Failure to thrive workup: dietary, psychosocial, organic (CF, celiac, congenital heart, renal tubular, endocrine)

— Severe acute malnutrition: WHO protocol with F-75 then F-100 formula; watch for refeeding

— Roux-en-Y and BPD-DS at highest risk for B12, iron, calcium, vitamin D, thiamine, copper, zinc, vitamin A, K

— Annual labs including iron studies, B12, 25-OH-D, PTH, A1c, lipid panel

— Routine supplementation: bariatric multivitamin + B12 + calcium citrate (NOT carbonate) + vitamin D + iron

— Wernicke encephalopathy within weeks of surgery if vomiting + no thiamine — emergency IV repletion

— HR <40, BP <90/60, T <36, glucose <60, K <3, BMI <14 (or rapid loss), orthostatic HR rise >20

— Refeeding hypophosphatemia risk highest in first 5–10 days

— Multidisciplinary: medical, psychiatry, nutrition, family-based therapy in adolescents

Step 3 management: Any post-bariatric patient with neurologic symptoms (confusion, ataxia, nystagmus) gets empiric IV thiamine 500 mg TID before any glucose-containing fluid — do not wait for levels.

Board pearl: Calcium citrate (not carbonate) post-RYGB because acid-independent absorption.

Pregnancy:

Pediatric malnutrition (AND/ASPEN pediatric criteria use z-scores):

Post-bariatric surgery (lifelong screening):

Anorexia nervosa inpatient admission criteria:

HIV/cancer cachexia: treat underlying disease; consider mirtazapine, megestrol cautiously; resistance exercise.

Complications and Adverse Outcomes

— Mechanism: chronic starvation depletes intracellular phosphate, magnesium, potassium, thiamine; refeeding triggers insulin surge → intracellular shift → severe hypophosphatemia, hypoMg, hypoK, thiamine deficiency

— Clinical: arrhythmia (long QT, torsades), CHF, respiratory failure, rhabdomyolysis, hemolytic anemia, seizures, Wernicke, death

— Highest risk: BMI <16, fasting >10 days, alcohol use, anorexia nervosa, post-bariatric, chemotherapy

— Treatment: stop or slow feeds, replete electrolytes IV, continue thiamine

— Triad: confusion, ophthalmoplegia, ataxia (often incomplete)

— Treat empirically — thiamine 500 mg IV TID × 3 days, then 250 mg IV daily × 5 days, then oral

— Korsakoff: irreversible confabulation and anterograde amnesia from untreated Wernicke

— Malnutrition is an independent risk factor; protein 1.25–1.5 g/kg + arginine + vitamin C + zinc supplementation accelerates healing

— Braden score includes nutrition subscale

— Lymphopenia, impaired cell-mediated immunity → pneumonia, line infections, surgical site infections, tuberculosis reactivation

— CLABSI, catheter occlusion, venous thrombosis

— Hepatobiliary: cholestasis, steatosis, PNALD; biliary sludge from gut rest

— Hyperglycemia, electrolyte derangements, hypertriglyceridemia from lipids

— Metabolic bone disease in long-term PN

— Aspiration pneumonia (HOB ≥30°, post-pyloric placement reduces risk)

— Tube clogging, dislodgement, diarrhea (formula osmolality, sorbitol in liquid meds, C. difficile)

— Buried bumper in chronic PEG

Board pearl: Sudden cardiac death in a refed anorexia nervosa patient = hypophosphatemia-induced arrhythmia. Check phos before checking the ECG.

CCS pearl: New diarrhea on tube feeds — first rule out C. difficile and sorbitol-containing liquid medications before changing the formula.

Refeeding syndrome (the highest-stakes complication):

Wernicke-Korsakoff syndrome:

Pressure injuries and impaired wound healing:

Immunosuppression:

Sarcopenia and frailty cascade: falls, fractures, longer LOS, postoperative complications, 30-day readmission.

PN-specific complications:

EN-specific complications:

Escalation of Care — When to Admit, Consult, or ICU

— BMI <14 (or rapid loss to BMI <15)

— Refeeding electrolyte derangement (K <3.0, PO₄ <2.0, Mg <1.5)

— Hemodynamic instability: HR <40, SBP <90, orthostatic, T <36

— Glucose <60 or unable to tolerate oral intake

— Suicidality or severe anorexia nervosa not responding to outpatient care

— Acute organ failure: liver, renal, cardiac (long QT, CHF)

— Inability to safely refeed at home (lack of supervision, severe behavioral disorder)

— Severe arrhythmia, hemodynamic compromise from refeeding

— Respiratory failure (diaphragmatic weakness, pneumonia)

— Severe rhabdomyolysis or DKA-like state

— Wernicke with altered mental status requiring close monitoring

— Registered dietitian — all patients with screening-positive malnutrition, within 24–48 h of admission

— Speech-language pathology — any dysphagia, stroke, post-extubation, head/neck cancer; bedside swallow then modified barium swallow or FEES

— GI — chronic malabsorption, suspected celiac/IBD/pancreatic insufficiency, PEG placement

— Psychiatry — anorexia/bulimia, severe depression, capacity questions on refusing feeding

— Endocrinology — uncontrolled diabetes, thyroid disease, adrenal insufficiency

— Palliative care — cachexia in advanced cancer, dementia, end-stage organ disease; goals of care

— Social work — food insecurity, SNAP enrollment, Meals on Wheels, elder neglect

Step 3 management: A frail elderly nursing home patient admitted with pneumonia and 15% weight loss over 6 months: order dietitian consult, SLP swallow evaluation, depression screen, dental consult, and social work for placement review — Step 3 rewards this multidisciplinary mindset.

CCS pearl: Don't forget the "call consult" actions in CCS — nutrition consults and SLP evaluations move the clock forward and earn credit.

Outpatient → inpatient admission criteria:

ICU triage:

Consults — who and when:

Nutrition support team consult for any patient on PN >7 days or complex EN.

Key Differentials — Other Causes of Weight Loss (Same Category)

— Major depressive disorder — anhedonia, sleep change, PHQ-9 ≥10; among most common causes in elderly

— Anorexia nervosa / bulimia / ARFID — body image, restrictive behaviors, purging

— Substance use disorders — alcohol, stimulants, opioids

— Dementia — forgets to eat, aphagia, behavioral

— Metformin (consider switch if persistent), SSRIs, opioids, digoxin, amphetamines/methylphenidate, topiramate, GLP-1 agonists (semaglutide, tirzepatide — increasingly relevant; expected weight loss but excessive in elderly), chemotherapy, levothyroxine over-replacement, anticholinergics

— Dysphagia: stroke, achalasia, esophageal cancer, Zenker

— Peptic ulcer, gastroparesis, gastric outlet obstruction

— Celiac disease — iron deficiency, diarrhea, dermatitis herpetiformis; tTG-IgA + total IgA

— IBD (Crohn especially) — fistulae, bypass of absorptive surface

— Chronic pancreatitis / pancreatic insufficiency — steatorrhea, fecal elastase low

— SIBO, short bowel syndrome, post-Roux-en-Y

— Mesenteric ischemia — postprandial pain, food fear

— Oral/dental disease — ill-fitting dentures, periodontitis

— Food insecurity, poverty, isolation

— Elder neglect or abuse

— Caregiver burnout

Key distinction: In an elderly patient with unintentional weight loss, the top three diagnoses that account for >50% of cases are depression, cancer, and benign GI disease (dysphagia, PUD, malabsorption) — not occult thyroid disease or rare endocrinopathies. Workup should target this distribution.

Board pearl: A semaglutide user with rapid 15% weight loss, sarcopenia, and dehydration may need dose reduction or discontinuation plus dietitian referral — GLP-1 cachexia is an emerging Step 3 scenario.

Differentials grouped as involuntary weight loss with anorexia/decreased intake:

Psychiatric:

Medication-induced anorexia:

GI causes (decreased intake or malabsorption):

Social/environmental:

Key Differentials — Catabolic and Systemic Causes

— Solid tumors (lung, GI, pancreatic — highest cachexia rates), lymphoma, multiple myeloma

— B symptoms: fever, night sweats, weight loss

— Workup: age-appropriate screening, directed imaging based on signs

— Hyperthyroidism / thyroid storm — heat intolerance, tachycardia, tremor

— Type 1 DM / uncontrolled T2DM — polyuria, polydipsia, weight loss

— Adrenal insufficiency — fatigue, hyperpigmentation, hyponatremia, hyperkalemia

— Pheochromocytoma — episodic hypertension, weight loss

— Hypercalcemia of malignancy — anorexia, constipation

— HIV/AIDS wasting syndrome — must screen

— Tuberculosis — pulmonary or extrapulmonary

— Chronic hepatitis, endocarditis, occult abscess, parasitic infections (Giardia, strongyloides in travelers/immigrants)

— COVID post-acute sequelae with anosmia and anorexia

— CHF cachexia — advanced HF with sarcopenia, neurohormonal/inflammatory drive

— COPD cachexia — increased work of breathing, TNF-α; "pink puffer" thin phenotype

— CKD/ESRD — protein-energy wasting

— Cirrhosis — sarcopenia from hyperammonemia, decreased BCAAs

— RA, SLE, vasculitides — chronic inflammation drives cachexia

— Giant cell arteritis in elderly with weight loss and headache

— ALS, advanced Parkinson, post-stroke dysphagia, dementia

Key distinction: Cachexia (disease-driven catabolism) vs starvation (intake-driven). Cachexia features inflammation, normal-to-elevated REE, anorexia, and does not fully reverse with feeding alone — must treat the underlying disease. Pure starvation lowers REE and reverses with refeeding.

Board pearl: Unexplained weight loss + elevated ESR/CRP + age >50 → think occult malignancy, giant cell arteritis, endocarditis, or TB before idiopathic.

Differentials grouped as increased metabolic demand or losses despite adequate intake:

Malignancy:

Endocrine:

Infectious:

Chronic organ failure:

Rheumatologic/inflammatory:

Neurologic:

Secondary Prevention, Discharge Planning, and Long-Term Plan

— Document discharge weight and trajectory

— Specify diet order: regular, dysphagia-modified (IDDSI level), diabetic, etc. — liberalize when possible

— Prescribe ONS: "Ensure Plus 240 mL TID between meals × 90 days"

— Continue thiamine, multivitamin, and any electrolyte repletion

— If on EN at discharge: tube type, formula, rate, flush schedule, home health for tube care, supplies

— If on home PN: dedicated home infusion company, weekly labs, monthly clinic

— Dietitian outpatient follow-up within 1–2 weeks

— Track weight at every visit, target gain of 0.5–1 kg/week until baseline restored

— Quarterly labs: CMP, CBC, prealbumin (trend, not single value), vitamin D, B12, iron

— Resistance exercise + adequate protein for sarcopenia reversal

— Treat underlying disease — antidepressants, thyroid replacement, smoking cessation, alcohol counseling, cancer-directed therapy

— Post-bariatric: lifelong daily bariatric multivitamin, B12, calcium citrate, vitamin D, iron; annual labs

— Cirrhosis: late-evening snack, 1.2–1.5 g/kg protein, BCAAs if HE, abstinence

— Cancer survivors: ongoing dietitian, resistance training

— CKD: adjust protein at dialysis transition

— Dementia / advanced illness: hand feeding over PEG; document goals of care

— Medicare covers MNT for diabetes and CKD (Part B); diagnosis code documentation is essential

— SNAP, WIC, Meals on Wheels, Senior Nutrition Program (Older Americans Act) — connect via social work

— Home enteral/parenteral nutrition coverage requires specific documentation (functional gut criteria for PN)

Step 3 management: A patient discharged after pneumonia with 10% weight loss should leave with (1) ONS prescription, (2) dietitian follow-up appointment, (3) PCP visit within 1 week, (4) home health nutrition screen, and (5) screening for depression and food insecurity documented in the after-visit summary.

Board pearl: Medicare reimburses outpatient MNT (90+ min year 1, 60+ min thereafter) for diabetes and renal disease only — for malnutrition, bill via E/M with nutrition counseling time.

Discharge nutrition plan checklist (Step 3 inpatient-to-outpatient transition):

Long-term outpatient management:

Secondary prevention by population:

Reimbursement and access:

Follow-Up, Monitoring, and Rehabilitation

— Daily weights at the same time, same scale, same clothing

— Strict intake and output

— Electrolytes (Mg, Phos, K, Ca) q12h × 72h, then daily until stable, then 2–3×/week

— Glucose 4–6× daily during PN

— LFTs and triglycerides weekly on PN

— CBC, prealbumin weekly (trend)

— Cardiac monitoring in severe refeeding risk

— Weekly weight (home scale or clinic) until stable

— Monthly clinic visit during recovery; quarterly once stable

— Labs at 1, 3, 6, 12 months

— Functional measures: grip, gait speed, SARC-F

— Resistance training 2–3×/week is essential to convert calorie/protein intake into lean mass — feeding without exercise gains fat preferentially

— Geriatric: chair stands, resistance bands, supervised PT

— Post-ICU: early mobility, PT/OT during admission; pulmonary rehab for COPD; cardiac rehab for HF

— Speech therapy for dysphagia rehabilitation with goal of advancing diet

— Occupational therapy for adaptive feeding devices (tremor, stroke, arthritis)

— Anorexia nervosa: CBT-E, family-based therapy (adolescents), specialty eating disorder programs

— Depression-related weight loss: SSRI or mirtazapine for combined depression and appetite stimulation

— Alcohol use disorder: medication (naltrexone, acamprosate) + behavioral support

— Smoking cessation: improves appetite and outcomes in COPD/cancer

— Malnutrition diagnosis (ICD-10 E43, E44, E46) affects DRG severity weighting — documentation matters

— 30-day readmission risk decreases with structured nutrition follow-up

CCS pearl: Order PT/OT consult, daily weights, and nutrition follow-up as standing discharge orders for any patient with documented malnutrition diagnosis.

Board pearl: "Feed plus train" — protein + resistance exercise — is the only proven combination to rebuild lean mass in sarcopenia. Feeding alone gains adipose.

Monitoring during active refeeding (inpatient):

Monitoring outpatient:

Rehabilitation and physical activity:

Behavioral and counseling:

Quality metrics:

Ethical, Legal, and Patient Safety Considerations

— A patient with decision-making capacity can refuse enteral or parenteral nutrition even if life-sustaining

— Capacity is decision-specific — assess: understanding of condition and consequences, appreciation of how it applies, reasoning, and consistent choice

— Anorexia nervosa raises complex capacity questions; severe cases may warrant involuntary treatment via psychiatric hold when life-threatening, jurisdiction-dependent

— Honor previously documented preferences regarding artificial nutrition (POLST/MOLST forms specifically address this)

— Surrogate hierarchy (state-dependent): healthcare agent → spouse → adult children → parents → siblings

— Substituted judgment standard: what would the patient want, not what does the family want

— Strong evidence: PEG feeding in advanced dementia does not prolong life, reduce aspiration, prevent pressure ulcers, or improve comfort

— Hand feeding (careful/comfort feeding) is preferred; AGS and Choosing Wisely both recommend against PEG

— Frame family discussions around quality of life, comfort, and dignity, not "starving the patient"

— Anorexia in dying patients is normal physiologic process

— Forced nutrition can cause distress, aspiration, edema, secretions

— Comfort feeding, oral care, ice chips, small tastes

— Suspected elder neglect (malnourished, dehydrated nursing home or community elder) → mandatory Adult Protective Services report in most US states

— Child neglect with failure to thrive → CPS report

— Document objective findings and your reporting

— Tube misplacement — verify NG by post-placement X-ray, not auscultation (Joint Commission)

— Wrong-route feeding — fatal events; ENFit connectors mandated

— CLABSI in PN — bundle adherence

— Medication errors in tube feeding (crushing extended-release, sorbitol-containing elixirs causing diarrhea)

Step 3 management: When a family insists on PEG placement in an advanced dementia patient, hold a structured goals-of-care conversation, share evidence that PEG does not prolong life or improve comfort, offer careful hand feeding as the standard of care, and document the discussion thoroughly. This is a frequent Step 3 ethics vignette.

Capacity and refusal of feeding:

Advance directives and surrogate decisions:

Artificial nutrition in advanced dementia:

End-of-life nutrition:

Mandatory reporting:

Patient safety concerns:

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: When boards mention BMI <16, weight loss >15%, alcohol use, or prolonged NPO, the diagnosis they want is refeeding risk — answer thiamine + low-rate refeeding + electrolyte monitoring.

Refeeding syndrome = hypophosphatemia, hypoMg, hypoK, thiamine deficiency → arrhythmia, CHF, respiratory failure

Wernicke = ophthalmoplegia + ataxia + confusion → IV thiamine before glucose

Korsakoff = irreversible confabulation/amnesia from untreated Wernicke

Marasmus = wasting, preserved albumin early; Kwashiorkor = edema, low albumin, fatty liver

Albumin = inflammation marker, not nutrition; prealbumin = short half-life, also acute-phase

GLIM criteria = ≥1 phenotypic + ≥1 etiologic

"If the gut works, use it" — EN > PN

EN in acute pancreatitis within 24–72 h improves outcomes

Start severely malnourished refeeding at 10 kcal/kg/day (5 kcal/kg if BMI <14)

Protein needs: 0.8 g/kg normal, 1.2–1.5 acute illness, 1.5–2.0 burns/trauma/CRRT, 0.6–0.8 pre-dialysis CKD, 1.2 cirrhosis (don't restrict)

Post-RYGB: deficiencies in B12, iron, calcium, vit D, thiamine, copper, A, K; use calcium citrate

Advanced dementia + PEG = no benefit; hand feed

Anorexia nervosa admission: HR <40, T <36, K <3, BMI <14

Hunger Vital Sign = 2-question food insecurity screen

MNA-SF = geriatric screen of choice

MST = quick hospital screen

L3 muscle index on CT = sarcopenia surrogate

Cancer cachexia = not fully reversed by feeding alone; treat underlying disease

Mirtazapine = best appetite stimulant in depressed elderly

Megestrol = VTE and adrenal suppression risk; avoid in frail

Cirrhosis = late-evening snack reduces overnight catabolism

Liberalize restrictive diets in nursing home elderly

Verify NG placement with X-ray, not auscultation

ENFit connectors prevent wrong-route feeding errors

MNT covered by Medicare for diabetes and CKD only

Vitamin C, zinc, arginine help wound healing

Pellagra triad: diarrhea, dermatitis, dementia (niacin)

Scurvy: petechiae, perifollicular hemorrhage, gum bleeding (vit C)

Bitot spots = vitamin A deficiency

Board Question Stem Patterns

Board pearl: Step 3 stems reward the systems-level move — dietitian consult, social work, SLP, family meeting, APS report — not just the right drug.

Stem 1 — Refeeding syndrome: A 28-yo woman with anorexia nervosa, BMI 13, admitted for bradycardia and hypothermia. Started on standard tube feeds. On day 3 develops weakness, confusion, ventricular ectopy. Most likely lab abnormality? → Severe hypophosphatemia. Next step: stop feeds, replete electrolytes, restart at 5–10 kcal/kg with thiamine pretreatment.

Stem 2 — Wernicke prevention: Malnourished alcoholic in ED, hypoglycemic. Best initial step before D50? → IV thiamine 500 mg.

Stem 3 — PEG in dementia: 85-yo with advanced Alzheimer, recurrent aspiration, family requests PEG. Best recommendation? → Careful hand feeding; PEG does not improve survival or reduce aspiration.

Stem 4 — Albumin misinterpretation: Hospitalized septic patient, albumin 2.1. Question asks for diagnosis. Wrong answer: malnutrition. Right answer: acute-phase inflammatory response.

Stem 5 — Cirrhosis protein: Cirrhotic with HE asks if protein should be restricted. Best advice? → Continue 1.2–1.5 g/kg/day protein; treat HE with lactulose/rifaximin; add late-evening snack.

Stem 6 — Post-bariatric neuro symptoms: 6 weeks post-RYGB with vomiting, now confused with ataxia and nystagmus. Diagnosis and treatment? → Wernicke; IV thiamine 500 mg TID.

Stem 7 — Nursing home weight loss: 82-yo on cardiac/diabetic/low-salt diet has lost 8% over 6 months. Best initial intervention? → Liberalize the diet + dietitian referral + screen for depression.

Stem 8 — Pancreatitis nutrition: 50-yo with severe acute pancreatitis on day 3 NPO. Best nutrition plan? → Initiate enteral nutrition via NG or NJ within 24–72 h; not TPN, not prolonged NPO.

Stem 9 — Mandatory report: Cachectic 78-yo woman lives with adult son who controls finances and food. Bruises on arms. Next step? → Report to Adult Protective Services.

Stem 10 — Outpatient elderly: Depressed 75-yo widower, 7% weight loss, normal labs. Best pharmacologic choice for appetite and mood? → Mirtazapine.

Stem 11 — Capacity refusal: 35-yo with capacity refuses TPN for end-stage cancer. Correct action? → Honor the refusal, offer palliative care.

One-Line Recap

Protein-calorie malnutrition is a phenotypic + etiologic diagnosis (weight loss, low BMI, reduced muscle mass plus reduced intake or inflammatory disease) — not a number on an albumin panel — and Step 3 success hinges on identifying refeeding risk, giving thiamine before glucose, choosing the right route (gut first), and connecting the patient to dietitian, social work, and longitudinal follow-up.

Board pearl: The single highest-yield Step 3 reflex in any malnourished patient: thiamine first, then dextrose; phosphorus check, then feeds; dietitian consult, then discharge.

Diagnose with GLIM/ASPEN criteria; use MST, MUST, NRS-2002, or MNA-SF for screening; never rely on albumin alone.

Refeed safely: identify NICE high-risk criteria (BMI <16, fasting >10 days, alcohol use), start at 5–10 kcal/kg/day, give thiamine 100–300 mg IV before any dextrose, replete K/Mg/PO₄ aggressively, monitor electrolytes q12h × 72 h.

Choose the route: oral fortification + ONS first; enteral if gut works and intake inadequate >7 days; parenteral only when gut nonfunctional. EN within 24–72 h in severe pancreatitis and ICU; avoid PEG in advanced dementia.

Tailor by population: cirrhosis 1.2–1.5 g/kg protein with late-evening snack (do not restrict); pre-dialysis CKD 0.6–0.8, dialysis 1.2; post-bariatric lifelong B12, iron, calcium citrate, vitamin D, thiamine; elderly nursing home → liberalize restrictive diets, screen for depression, dentition, drugs.

Discharge with documented diagnosis (ICD-10 E43/44/46), ONS prescription, dietitian follow-up within 1–2 weeks, resistance exercise plan, and screening for food insecurity (Hunger Vital Sign) plus connection to SNAP/Meals on Wheels.

Ethics: respect capacity-based refusal; in advanced dementia, hand feeding over PEG; report suspected elder or child neglect to APS/CPS; verify NG placement with X-ray, not auscultation.