Renal & Urinary

Polycystic kidney disease: surveillance and complications

Clinical Overview and When to Suspect ADPKD

— PKD1 (chromosome 16, ~78%): earlier ESRD, median ~age 55

— PKD2 (chromosome 4, ~15%): milder course, median ESRD ~age 70

— PKD3 (GANAB, DNAJB11, others): atypical, often mild

— Hypertension before age 35 plus family history of kidney disease

— Recurrent gross hematuria or flank pain in a young adult

— Incidental finding of bilateral renal cysts on imaging

— New CKD with normal urine sediment and large kidneys on US

— Family history of intracranial aneurysm (ICA) or sudden death

— Hepatic cysts (>80% by age 50, more common in women)

— Intracranial aneurysms (~9–12%, vs 2% general population)

— Mitral valve prolapse, aortic root dilation, aortic dissection

— Colonic diverticulosis, abdominal wall and inguinal hernias

— Seminal vesicle cysts (male infertility)

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, affecting ~1 in 400–1000 live births and accounting for ~5% of US ESRD cases.

Genetics drive phenotype:

ARPKD is a separate entity — autosomal recessive, presents in infancy/childhood with hepatic fibrosis and oligohydramnios; do not confuse on exam.

When to suspect ADPKD in an adult:

Extrarenal manifestations establish the systemic nature:

Natural history: cysts develop in utero, but GFR is preserved for decades via compensatory hyperfiltration. Once GFR begins to decline (typically 4th–5th decade), the rate averages ~4.4–5.9 mL/min/year in PKD1.

Board pearl: A young hypertensive patient with a parent on dialysis and an unruptured aneurysm in a first-degree relative should prompt ADPKD evaluation and screening for intracranial aneurysm — not a routine CKD workup. Hypertension is the earliest and most modifiable manifestation, often preceding measurable GFR decline by 10–20 years, so blood pressure control is the single highest-yield intervention you can initiate at first contact.

Presentation Patterns and Key History

— Acute flank pain: cyst hemorrhage, cyst infection, nephrolithiasis (uric acid and calcium oxalate stones in 20–25%), or urinary obstruction

— Chronic dull flank/back pain: mass effect from kidney enlargement (often >1500 mL total kidney volume)

— Acute severe headache "worst of life": ruptured intracranial aneurysm until proven otherwise

— Dialysis, transplant, or "kidney failure" in relatives

— Sudden death, "brain bleed," or aneurysm clipping

— Liver cysts, hernias, early hypertension

— De novo mutations occur in ~10%, so absent family history doesn't exclude ADPKD

Hypertension (60–70% before CKD) is typically the index finding — driven by intrarenal RAAS activation from cyst compression of vasculature.

Pain syndromes — clarify the character because it drives workup:

Hematuria: gross hematuria in ~40% lifetime; usually self-limited cyst hemorrhage lasting <7 days. Persistent hematuria >1 week → evaluate for stone, infection, or RCC.

UTI/pyelonephritis vs cyst infection — both present with fever and flank pain, but cyst infections often have negative urine cultures because the cyst doesn't communicate with the collecting system.

Family history is essential — ask specifically about:

Reproductive history in women: prior pregnancies tolerated? Estrogen exposure accelerates polycystic liver disease (PLD) — important for OCP and HRT counseling.

Symptom timeline matters for prognosis: symptom onset before age 35 (the PROPKD score uses early HTN, early urologic events, and male sex with PKD1 truncating mutation) predicts rapid progression.

Key distinction: Cyst hemorrhage = pain + hematuria, afebrile, resolves in days. Cyst infection = pain + fever, often without hematuria, requires lipophilic antibiotics. Misidentifying these on a stem changes the entire management pathway — one needs hydration and analgesia, the other needs ciprofloxacin or TMP-SMX for 4–6 weeks and possibly drainage.

Physical Exam Findings and Hemodynamic Assessment

— BP often elevated by age 30, frequently before any cyst symptoms

— Target per KDIGO 2025 and HALT-PKD: <110/75 mmHg in young (<50 yo) ADPKD patients with eGFR >60 and low cardiovascular risk; otherwise standard <130/80

— Bilateral flank masses — ballotable, nodular, may extend below costal margin or to pelvis in advanced disease

— Hepatomegaly with palpable nodular liver edge (polycystic liver)

— Inguinal/umbilical/ventral hernias from abdominal wall weakness and increased intra-abdominal pressure

— Mid-systolic click and late systolic murmur of mitral valve prolapse (~25%)

— Early diastolic murmur suggesting aortic regurgitation from aortic root dilation

— LVH from chronic hypertension — sustained PMI, S4

— Cranial nerve III palsy (down-and-out eye, mydriasis) → posterior communicating artery aneurysm

— Sudden severe headache with meningismus → subarachnoid hemorrhage

— Always document baseline neuro status in known ADPKD

— JVP elevation, edema → suggests CKD progression with volume overload

— Orthostatic hypotension on aggressive antihypertensives — common pitfall

Vital signs first — hypertension is the dominant finding:

Abdominal exam:

Cardiovascular exam:

Neurologic exam — critical screening:

Skin/MSK: Not a classic finding — if you see angiofibromas, ash-leaf macules, or shagreen patches, think tuberous sclerosis (TSC) instead, which can cause renal cysts plus angiomyolipomas.

Volume/hemodynamic assessment:

Step 3 management: When you palpate bilateral flank masses on a hypertensive 35-year-old, the order set is: CMP, UA, urine albumin/creatinine ratio, renal ultrasound, and lipid panel, then home BP monitoring with a goal of <110/75 if young and otherwise healthy. Do not jump to CT — ultrasound is the first-line confirmatory study and avoids contrast in someone with potentially declining GFR.

Diagnostic Workup — Initial Labs and Imaging

— BMP/CMP: baseline creatinine, eGFR, electrolytes (hyperkalemia, metabolic acidosis if advanced CKD)

— CBC: anemia of CKD; conversely erythrocytosis can occur from cyst-derived erythropoietin

— Urinalysis: microscopic hematuria, mild proteinuria (<1 g/day typical — heavy proteinuria suggests alternate diagnosis)

— Urine albumin-to-creatinine ratio at baseline and annually

— Fasting lipids, HbA1c for cardiovascular risk stratification

— Uric acid — hyperuricemia common; gout/stones risk

— Ravine/Pei-Ravine ultrasound criteria for at-risk individuals (positive family history):

— Age 15–39: ≥3 cysts (unilateral or bilateral) — diagnostic

— Age 40–59: ≥2 cysts in each kidney

— Age ≥60: ≥4 cysts in each kidney

— Excluding ADPKD in at-risk patient age ≥40: <2 cysts has near-100% NPV

— Cyst hemorrhage (hyperdense, non-enhancing)

— Cyst infection (thick walls, gas, perinephric stranding)

— Stones (CT without contrast)

— Suspected RCC (enhancement on contrast study)

— Equivocal imaging in young at-risk patient

— Negative family history with new cysts

— Living-related donor evaluation when imaging is borderline

— Reproductive planning / PGD

Initial laboratory panel:

Imaging — renal ultrasound is first-line:

CT or MRI when ultrasound equivocal, or to characterize complications:

MRI is the gold standard for measuring total kidney volume (TKV) — required for Mayo Imaging Classification and tolvaptan eligibility.

Genetic testing indications:

Board pearl: Heavy proteinuria (>1 g/day), red cell casts, or rapidly declining GFR out of proportion to TKV in an ADPKD patient should make you look for a superimposed glomerular disease — don't anchor on ADPKD as the sole explanation. Order serologies (ANA, ANCA, complements, hepatitis panel) and consider biopsy of non-cystic parenchyma.

Diagnostic Workup — Advanced and Risk-Stratifying Studies

— Requires height-adjusted total kidney volume (htTKV) by MRI or CT

— Class 1A–1E based on htTKV growth trajectory by age

— Class 1C, 1D, 1E = rapid progressors → eligible for tolvaptan

— Class 1A/1B = slow progressors → conservative management

— Class 2 = atypical (asymmetric, segmental cysts) — investigate alternative diagnoses

— Male sex (1 pt), HTN before age 35 (2 pts), first urologic event before 35 (2 pts), PKD1 truncating mutation (4 pts), PKD1 non-truncating (2 pts), PKD2 (0 pts)

— Score >6 predicts ESRD before age 60 with high specificity

— Indications:

— Family history of ICA or subarachnoid hemorrhage in any relative

— Personal history of aneurysm

— High-risk occupation (pilot, commercial driver)

— Pre-major surgery requiring anticoagulation

— Patient anxiety after counseling (shared decision)

— Routine universal screening is NOT recommended — most aneurysms are <7 mm with low rupture risk

— Rescreen every 5–10 years if initial scan negative and risk factors persist

— Truncating PKD1 mutations → worst prognosis

— Useful when prognosis affects management decisions (tolvaptan, transplant donor)

Mayo Imaging Classification (MIC) — the most important prognostic tool:

PROPKD score (clinical/genetic):

eGFR slope: serial creatinine over ≥3 years; decline >3 mL/min/year suggests rapid progression.

Intracranial aneurysm screening — MR angiography (MRA) without contrast is preferred:

Genetic testing (NGS panel for PKD1, PKD2, GANAB, DNAJB11, IFT140, ALG9):

Echocardiogram: not routine, but obtain if murmur, family history of valvular disease, or before pregnancy.

Step 3 management: A 32-year-old ADPKD patient with htTKV 750 mL/m and eGFR 75 falls into Mayo Class 1D. Next step: confirm rapid progression criteria, counsel on tolvaptan (Jynarque) with REMS enrollment for hepatotoxicity monitoring, and arrange nephrology co-management. Do not start tolvaptan without baseline LFTs and a serum sodium.

Risk Stratification and Management Logic

— Mayo Class 1C, 1D, or 1E

— eGFR decline ≥3 mL/min/year over ≥3 years

— eGFR <60 before age 55

— PROPKD score >6

— PKD1 truncating mutation with early HTN

1. Blood pressure control — RAAS blockade preferred (ACEi or ARB, not both)

— Target <110/75 if age <50, eGFR >60, low CV risk (HALT-PKD A)

— Target <130/80 otherwise

2. High water intake — ~3 L/day to suppress vasopressin and slow cyst growth (if no contraindication like hyponatremia or CHF)

3. Low sodium diet (<2 g/day) — slows TKV growth independent of BP

4. Moderate protein (0.75–1.0 g/kg/day) — avoid both extremes

5. Avoid caffeine excess, smoking, NSAIDs — NSAIDs worsen cyst growth and CKD

6. Statin per ASCVD risk; some evidence for slowing TKV in young patients

7. Lifestyle: weight optimization, exercise (contact sports controversial — large kidneys at risk for traumatic rupture)

— Tolvaptan (V2 receptor antagonist) — only FDA-approved drug to slow GFR decline; for rapid progressors with eGFR 25–90

— Chronic NSAIDs, nephrotoxic contrast when avoidable, estrogen-heavy contraceptives in women with significant PLD

— Caffeine excess (theoretical cAMP-mediated cyst growth)

Stratify every ADPKD patient into "rapid" vs "slow" progressor — this drives whether disease-modifying therapy is offered.

Rapid progression criteria (any of):

Foundational management for ALL ADPKD patients:

Disease-modifying therapy:

Avoid in ADPKD:

CCS pearl: On a CCS case of newly diagnosed ADPKD, your initial order block should include: ACE inhibitor, dietary counseling, home BP cuff, urine ACR, lipid panel, hepatitis B vaccination (for future transplant eligibility), genetic counseling referral, and follow-up in 3 months. Hepatitis B vaccination is frequently forgotten but earns points by anticipating eventual transplant candidacy.

Pharmacotherapy — First-Line Regimen

— Lisinopril 5–10 mg daily, titrate to goal BP and tolerability

— Or losartan 50–100 mg daily if ACEi cough/angioedema

— Monitor K+ and creatinine 1–2 weeks after initiation/titration; up to 30% creatinine rise is acceptable

— Dual RAAS blockade is contraindicated (HALT-PKD showed no benefit, more harm)

— Indication: adults with ADPKD at risk of rapid progression (Mayo 1C–1E, or eGFR decline ≥3/yr), eGFR ≥25

— Dosing: split-dose 60 mg AM / 30 mg PM, titrate to 90/30 mg as tolerated

— Mechanism: blocks vasopressin-mediated cAMP rise in collecting duct → slows cyst growth (~3 mL/min over 3 years in TEMPO 3:4)

— Adverse effects:

— Aquaresis: polyuria 5–6 L/day, polydipsia, nocturia — counsel patients

— Hepatotoxicity: idiosyncratic ALT/AST elevations >3× ULN in ~5%; REMS program requires LFTs monthly × 18 months, then q3 months

— Hyperuricemia, gout

— Hypernatremia if water intake inadequate

— Contraindications: significant liver disease, hypovolemia, uncorrected hypernatremia, inability to drink water freely

— Thiazide (chlorthalidone or HCTZ) if eGFR >30

— Calcium channel blocker (amlodipine) — neutral on cysts

— Loop diuretic if eGFR <30 or volume overload

— Avoid beta-blockers as monotherapy unless concurrent indication (CAD, HFrEF)

ACE inhibitor or ARB — cornerstone for hypertension and proteinuria:

Tolvaptan (Jynarque) — selective V2 receptor antagonist, the only disease-modifying agent:

Add-on antihypertensives if RAAS blockade insufficient:

Statins: moderate-intensity per ASCVD risk; pravastatin studied in pediatric ADPKD with TKV benefit.

Bicarbonate for metabolic acidosis (HCO3 <22) — slows CKD progression.

SGLT2 inhibitors: not currently recommended in ADPKD — excluded from major trials, theoretical concern for cyst growth via tubular glucose load and osmotic effects. Use only with specialist input.

Board pearl: Tolvaptan's signature side effect on exam is acute ALT elevation 3–18 months after start. The answer is hold drug, recheck LFTs in 72 hours, and do not rechallenge if total bilirubin >2× ULN with ALT >3× ULN (Hy's law signal).

Procedural and Surgical Management

— Percutaneous cyst aspiration + sclerotherapy (ethanol): for dominant symptomatic cyst causing pain or obstruction

— Laparoscopic cyst fenestration/decortication: multiple symptomatic cysts; effective for pain but doesn't slow CKD

— Transcatheter renal artery embolization: massive kidneys causing pre-transplant space limitation or refractory pain — avoids nephrectomy morbidity

— Unilateral or bilateral nephrectomy: for recurrent infection, suspected malignancy, or to create space for transplant

— Uric acid stones common → urinary alkalinization (potassium citrate) plus hydration

— Shock-wave lithotripsy (SWL) acceptable for stones <2 cm

— Ureteroscopy preferred for larger stones — percutaneous nephrolithotomy carries higher complication risk due to distorted anatomy

— Lipophilic antibiotics penetrate cyst wall: ciprofloxacin, TMP-SMX, clindamycin, chloramphenicol

— Hydrophilic agents (aminoglycosides, beta-lactams) penetrate poorly — inadequate monotherapy

— Duration: 4–6 weeks minimum; some require percutaneous drainage if no defervescence in 72 hours

— Image-guided drainage if cyst >5 cm or persistent fever

— <7 mm, asymptomatic, anterior circulation → conservative with serial MRA every 6–24 months

— ≥7 mm, posterior circulation, symptomatic, growing, or prior SAH → neurosurgical/endovascular intervention (clipping vs coiling)

— Kidney transplantation is the treatment of choice for ESRD — outcomes equal or better than non-PKD recipients

— Native nephrectomy before/at transplant if: massive size limits graft placement, recurrent infection, intractable pain, suspected RCC, severe hematuria

— Hemodialysis and peritoneal dialysis both feasible; large kidneys may limit PD catheter placement

Cyst-directed interventions — reserved for symptomatic complications, not routine:

Stone management — modified approach due to anatomy:

Cyst infection management:

Intracranial aneurysm management:

Renal replacement therapy:

CCS pearl: A febrile ADPKD patient with negative urine cultures, flank pain, and a thick-walled cyst on CT needs ciprofloxacin 400 mg IV q12h, blood cultures, and IR consult for percutaneous drainage if no improvement at 72 hours. Ordering ceftriaxone alone is a common wrong move — it doesn't penetrate cysts.

Special Populations — Elderly and Renal/Hepatic Impairment

— Often PKD2 phenotype — milder, presents later, slower progression

— Many reach 70s–80s with preserved GFR

— Deprescribe as appropriate: relax BP target to <130/80 to avoid orthostasis and falls; tolvaptan generally not initiated >age 55 due to limited benefit window

— Higher RCC risk in long-standing disease — maintain imaging surveillance threshold

— Tolvaptan not approved for eGFR <25; discontinue when eGFR falls below this

— RAAS blockade: continue unless K+ >5.5 refractory, AKI, or symptomatic hypotension — recent data (STOP-ACEi) support continuation even at low GFR

— Manage CKD complications: anemia (ESA when Hgb <10), bone-mineral disease (phosphate binders, active vitamin D), acidosis (bicarbonate), hyperkalemia (patiromer, dietary)

— Vaccinate: hepatitis B series (with high-dose protocol), pneumococcal, influenza, COVID, RSV — pre-transplant workup

— Synthetic liver function usually preserved despite massive hepatomegaly

— Symptoms: early satiety, dyspnea, ascites, portal hypertension (rare)

— Avoid estrogens (OCPs, HRT) — accelerate PLD growth

— Somatostatin analogs (octreotide, lanreotide) can reduce liver volume modestly

— Severe symptomatic PLD → fenestration, segmental resection, or liver/combined liver-kidney transplant

— Avoid NSAIDs entirely

— Adjust gabapentin, allopurinol, metformin, DOACs per eGFR

— Contrast: use iso-osmolar agents, minimize volume, pre-hydrate with isotonic saline; gadolinium-based MRA with macrocyclic agents is acceptable at eGFR ≥30

— Tolvaptan contraindicated in significant liver disease

— Statins: prefer pravastatin or rosuvastatin (less hepatic metabolism)

Elderly ADPKD patients:

Advanced CKD (eGFR <30):

Polycystic liver disease (PLD) with hepatic dysfunction:

Dose adjustments in CKD:

Hepatic impairment specifically affecting drug choice:

Step 3 management: A 78-year-old ADPKD patient with eGFR 22 and recurrent UTIs presents for routine follow-up. Stop tolvaptan if still on it, refer for transplant evaluation if life expectancy and functional status support it, initiate AV fistula planning at eGFR <20, and review immunization status. Age alone is not a contraindication to transplant — biological age and frailty are.

Special Populations — Pregnancy, Pediatrics, and Reproductive Issues

— Generally well tolerated when baseline BP is controlled and creatinine is normal

— Risk factors for adverse outcomes: pre-existing HTN, eGFR <60, proteinuria >1 g/day

— Higher rates of preeclampsia (up to 40%), preterm delivery, IUGR

— Switch ACEi/ARB to labetalol or nifedipine preconception — RAAS blockers are teratogenic (fetal renal dysgenesis, oligohydramnios)

— Stop tolvaptan — pregnancy category contraindicated, ensure contraception during treatment

— Increased UTI/pyelonephritis incidence — low threshold for screening urine cultures each trimester

— 50% inheritance risk to offspring (autosomal dominant)

— Preimplantation genetic diagnosis (PGD) available for couples where causative mutation identified

— Discuss maternal CV risk if eGFR <60 or uncontrolled HTN

— Avoid combined estrogen-progestin OCPs in women with significant PLD — accelerates liver cyst growth

— Progestin-only methods, IUD (copper or levonorgestrel) preferred

— Most children asymptomatic; cysts detectable on US by adolescence

— Screening of at-risk minors is controversial — most guidelines recommend deferring imaging until adulthood unless symptoms develop, due to psychosocial/insurance implications and absence of pediatric-approved disease-modifying therapy

— Annual BP screening starting age 5 is universally recommended in at-risk children

— Pediatric HTN treated aggressively with ACEi — slows progression

— ARPKD — infants, hepatic fibrosis, large echogenic kidneys

— Tuberous sclerosis — angiomyolipomas, skin findings, seizures

— Nephronophthisis — bilateral small kidneys, no early HTN

— HNF1B mutations — MODY5, kidney cysts, pancreatic abnormalities

Pregnancy in ADPKD:

Pre-pregnancy counseling:

Contraception:

Pediatric ADPKD:

Differential in pediatric cystic kidney disease:

Board pearl: A 28-year-old with ADPKD planning pregnancy on lisinopril 20 mg and tolvaptan should have both medications stopped or switched preconception — lisinopril to labetalol/nifedipine, and tolvaptan discontinued with two weeks of established contraception before transition. Missing the teratogenicity counseling is a recurrent stem trap.

Complications and Adverse Outcomes

— Hypertension — earliest, ~60% before CKD onset

— Cyst hemorrhage — sudden flank pain + gross hematuria, afebrile, self-limited (5–7 days); manage with bed rest, hydration, analgesia (acetaminophen, not NSAIDs)

— Cyst infection — fever, flank pain, often culture-negative urine; requires lipophilic antibiotics × 4–6 weeks

— Nephrolithiasis — 20–25%, predominantly uric acid (low urine pH) and calcium oxalate

— Chronic pain — mechanical from kidney enlargement; ladder: acetaminophen → tramadol → cyst aspiration → denervation procedures; avoid chronic opioids

— Progressive CKD → ESRD — ~50% by age 60 in PKD1

— Renal cell carcinoma — incidence similar to general population but often bilateral/multifocal; suspect when solid enhancing lesion or rapidly enlarging cyst with wall thickening

— Intracranial aneurysm — 9–12% prevalence; rupture mortality ~50%; risk factors: family history of ICA, hypertension, smoking

— Polycystic liver disease — symptomatic in ~20%; mechanical symptoms, rare hepatic failure

— Cardiac valvular disease — mitral valve prolapse (25%), aortic regurgitation, aortic root dilation, aortic dissection

— Abdominal wall hernias — inguinal, umbilical, ventral; recurrent after repair

— Colonic diverticulosis — higher rates and complications (perforation) than general population

— Seminal vesicle cysts — male infertility

— Intracranial dolichoectasia — arterial elongation, occasionally symptomatic

— Tolvaptan: hepatotoxicity, hypernatremia, dehydration, gout

— ACEi/ARB: hyperkalemia, AKI, angioedema

Renal complications:

Extrarenal complications:

Complications of treatment:

Cardiovascular mortality is the leading cause of death — not ESRD — emphasizing aggressive risk factor management.

Key distinction: Cyst hemorrhage = pain + hematuria, no fever, hemoglobin may drop, self-resolves; cyst infection = pain + fever, often no hematuria, often negative urine culture, requires prolonged lipophilic antibiotics. Misclassifying these is the single most common exam pitfall in ADPKD complications.

When to Escalate — ICU, Consult, and Inpatient Triage

— Thunderclap headache in ADPKD → non-contrast CT head; if negative and high suspicion, LP for xanthochromia or CTA — subarachnoid hemorrhage until disproven; neurosurgery consult; BP control with nicardipine (avoid nitroprusside)

— Hypotension + flank pain + dropping Hgb → consider retroperitoneal hemorrhage from cyst rupture — CT abdomen, type and cross, IR consult for embolization if hemodynamically unstable

— Severe hyperkalemia (K+ >6.5 with EKG changes) → calcium gluconate, insulin/dextrose, dialysis access planning

— Septic cyst infection with hemodynamic instability → broad-spectrum lipophilic coverage (cipro + clindamycin or carbapenem if resistant), ICU admission, IR drainage

— Cyst infection requiring IV antibiotics and observation

— Obstructing stone with infection or AKI

— Uncontrolled hypertensive urgency/emergency

— Acute pain crisis unresponsive to outpatient regimen

— New AKI in established ADPKD requiring evaluation

— Nephrology — at diagnosis if rapid progressor, eGFR <60, refractory HTN, or recurrent complications

— Urology — recurrent stones, suspected RCC, persistent hematuria, refractory pain

— Neurosurgery / interventional neuroradiology — for aneurysms ≥7 mm or growing

— Hepatology / transplant surgery — for symptomatic PLD

— Genetic counseling — reproductive planning, family screening, donor evaluation

— Transplant nephrology — refer at eGFR ≤30 (or earlier) to allow preemptive transplant

— Interventional radiology — cyst drainage, embolization

Immediate ED / ICU triage:

Inpatient (non-ICU) admission criteria:

Specialist consultations:

Multidisciplinary clinic referral when available (many academic centers have dedicated PKD programs).

CCS pearl: When the stem describes a known ADPKD patient with "sudden severe headache, photophobia, neck stiffness," the order set is: non-contrast CT head STAT, neurosurgery consult, BP target SBP <140 with IV nicardipine, NPO, type and screen, and reverse any anticoagulation. Ordering LP before CT, or starting heparin for presumed migraine, is the trap.

Key Differentials — Other Cystic Kidney Diseases

— Infants/young children, oligohydramnios, Potter sequence, bilateral massive echogenic kidneys

— Congenital hepatic fibrosis with portal hypertension is a hallmark

— Recessive PKHD1 mutation

— Multiple renal cysts plus angiomyolipomas (AMLs)

— Skin findings: ash-leaf macules, facial angiofibromas, shagreen patch

— Seizures, cognitive impairment, cortical tubers

— Treatment: mTOR inhibitors (everolimus, sirolimus) shrink AMLs and may reduce cyst burden

— Renal cysts plus clear cell RCC (high lifetime risk)

— Hemangioblastomas (cerebellum, retina), pheochromocytoma, pancreatic cysts/NETs

— Autosomal dominant VHL gene

— Small to normal-sized kidneys, medullary cysts only, bland urine, slowly progressive CKD

— UMOD, MUC1, REN, HNF1B mutations

— Hyperuricemia and gout (UMOD type)

— Develops in long-standing dialysis patients (>3 years)

— Small atrophic kidneys with multiple cysts — opposite of ADPKD's enlarged kidneys

— Increased RCC risk — annual screening recommended

— Age-related, asymptomatic, anechoic on US (Bosniak I)

— Prevalence increases with age — by 70, ~30% have ≥1 cyst

— Not ADPKD unless meets Ravine criteria

— I (simple) → IIF (minimally complex, surveillance) → III/IV (surgical — increasing malignancy risk)

— Most common genetic cause of ESRD in children

— Small kidneys, corticomedullary cysts, polyuria, anemia early; associated with retinitis pigmentosa, hepatic fibrosis (Senior-Løken, Joubert syndromes)

Autosomal recessive PKD (ARPKD):

Tuberous sclerosis complex (TSC):

Von Hippel-Lindau (VHL):

Medullary cystic kidney disease / autosomal dominant tubulointerstitial kidney disease (ADTKD):

Acquired cystic kidney disease (ACKD):

Simple renal cysts:

Bosniak classification of complex cysts:

Nephronophthisis:

Key distinction: ADPKD = enlarged kidneys with bilateral cortical and medullary cysts ± extrarenal cysts/aneurysms; ADTKD/nephronophthisis = small to normal kidneys with medullary cysts and bland urine; ACKD = small atrophic kidneys with cysts in a dialysis patient. Kidney size + cyst location + clinical context resolves nearly every stem.

Key Differentials — Non-Cystic Causes of Similar Presentations

— Renovascular disease — fibromuscular dysplasia (string-of-beads on CTA), atherosclerotic renal artery stenosis

— Primary aldosteronism — hypokalemia, suppressed renin, elevated aldosterone:renin ratio

— Pheochromocytoma — paroxysmal HTN, headache, palpitations, sweating; plasma/urine metanephrines

— Coarctation of the aorta — radio-femoral delay, BP differential between arms and legs

— Cushing syndrome — central obesity, striae, weakness, glucose intolerance

— Nephrolithiasis alone — CT KUB stone protocol

— Pyelonephritis — fever, pyuria, positive culture

— Renal cell carcinoma — solid enhancing mass, weight loss, paraneoplastic syndromes (hypercalcemia, polycythemia)

— Renal infarct — atrial fibrillation, sudden flank pain, LDH elevation

— Papillary necrosis — diabetes, sickle cell, analgesic abuse

— IgA nephropathy — synpharyngitic gross hematuria

— Loin-pain hematuria syndrome — diagnosis of exclusion

— Diabetic nephropathy — early hyperfiltration with enlargement

— HIV-associated nephropathy — echogenic enlarged kidneys, heavy proteinuria

— Infiltrative disease — lymphoma, amyloidosis, multiple myeloma cast nephropathy

— Bilateral renal vein thrombosis — nephrotic syndrome (membranous), enlarged kidneys

— Hypertensive emergency, migraine, cluster headache, venous sinus thrombosis, pituitary apoplexy

— Hydronephrosis — obstructive, smooth contour on imaging

— Renal cell carcinoma — typically unilateral, solid

— Splenomegaly, hepatomegaly of other etiologies

Hypertension in young adult (mimicking early ADPKD):

Flank pain + hematuria differentials:

Bilateral large kidneys (non-cystic):

Headache differentials beyond aneurysm:

Abdominal mass differentials:

Step 3 management: A 28-year-old with HTN, BMI 24, no family history, and normal renal ultrasound does not have ADPKD — workup secondary HTN: aldosterone:renin ratio, plasma metanephrines, TSH, renal artery Doppler/CTA. Anchoring on ADPKD without family history or imaging support is a classic distractor.

Secondary Prevention and Long-Term Plan

— ACE inhibitor or ARB at maximally tolerated dose for BP <110/75 (young, eGFR >60) or <130/80

— Tolvaptan for rapid progressors with eGFR 25–90, enrolled in REMS

— Moderate-intensity statin per ASCVD risk

— Bicarbonate if metabolic acidosis (HCO3 <22)

— Potassium binder (patiromer, sodium zirconium cyclosilicate) if RAAS-limiting hyperkalemia

— Phosphate binder, active vitamin D, calcimimetic in advanced CKD

— ESA if anemia of CKD with Hgb <10

— Allopurinol if symptomatic hyperuricemia / gout

— Potassium citrate for uric acid stones (urine alkalinization)

— 3 L/day water intake unless contraindicated — slows cyst growth via vasopressin suppression

— Sodium <2 g/day

— Moderate protein (0.75–1.0 g/kg/day)

— Smoking cessation — accelerates aneurysm risk and CKD

— Caffeine in moderation

— Avoid contact sports if kidneys massively enlarged

— Weight optimization (BMI <25 reduces TKV growth)

— Hepatitis B series with high-dose protocol; check anti-HBs titer

— Pneumococcal (PCV20 or PCV15 + PPSV23)

— Annual influenza, COVID-19, RSV (age-eligible)

— Avoid live vaccines once on immunosuppression post-transplant

— Vascular access mapping

— Cross-matching, HLA typing

— Living donor evaluation (screen donors for ADPKD if related)

— Address contraindications: malignancy clearance, dental, cardiac stress testing

— Chronic NSAIDs, nephrotoxic antibiotics when avoidable, herbal supplements with renal toxicity (aristolochic acid), recreational stimulants

— Estrogen-containing contraceptives in women with PLD

Discharge / outpatient medication checklist:

Lifestyle prescription:

Vaccination program (CKD/transplant-anticipatory):

Transplant preparation (start at eGFR <30):

Avoid:

Board pearl: Hepatitis B vaccination is the single most under-ordered preventive measure in CKD/ADPKD stems. Order it at diagnosis — seroconversion rates drop significantly as GFR falls, so early high-dose vaccination optimizes future transplant candidacy.

Follow-Up, Monitoring, and Counseling

— Every 6–12 months: BP review, weight, BMP (creatinine/eGFR, electrolytes), CBC, urine albumin/creatinine ratio, fasting lipids

— Annually: HbA1c if diabetic or at risk, urate, calcium/phosphate/PTH if eGFR <60

— Every 3–5 years: MRI for TKV in rapid progressors; imaging less often in slow progressors

— Home BP monitoring — twice daily readings, log review at visits

— LFTs monthly × 18 months, then every 3 months

— Sodium and urea every 3 months

— Uric acid annually

— Initial MRA if indication present (family history of ICA/SAH, high-risk occupation, pre-major surgery)

— Repeat every 5–10 years if negative and risk factors persist

— Shorter interval (1–2 years) for known small unruptured aneurysm

— eGFR 30–60: every 3–6 months

— eGFR <30: every 1–3 months, plus mineral bone disease panel

— Transplant referral at eGFR ≤30

— Genetic counseling for family planning, sibling/offspring screening decisions

— Discuss psychosocial impact — depression and anxiety common, especially around diagnosis and as relatives progress

— Insurance/employment implications of genetic testing — GINA (Genetic Information Nondiscrimination Act) protects health insurance and employment but not life, disability, or long-term care insurance

— Pregnancy planning — preconception medication review, PGD options

— Living donor decisions for family members

— Advance care planning at later stages

Routine monitoring cadence (stable ADPKD, eGFR >60):

Tolvaptan-specific monitoring (REMS):

Aneurysm surveillance:

Stage-based CKD monitoring intensifies as eGFR falls:

Counseling priorities:

Patient education materials: PKD Foundation resources, dietary handouts, water intake tracking apps.

Step 3 management: A patient with new ADPKD diagnosis and Mayo Class 1B (slow progressor) does not need annual MRI — clinical monitoring with BP, eGFR, and urine ACR every 6–12 months suffices. Reserve MRI for rapid progressors or those considering tolvaptan. Over-imaging is an exam distractor.

Ethical, Legal, and Patient Safety Considerations

— Generally deferred until adulthood unless symptoms or imaging changes; testing asymptomatic children removes their future autonomy and may cause insurance complications

— Pediatric counseling should focus on BP screening from age 5, healthy lifestyle, and deferred imaging

— Prohibits discrimination by health insurers and employers based on genetic information

— Does NOT apply to life, disability, or long-term care insurance — patients must be counseled before testing

— Does not cover military or some federal employees

— Family members are common donor candidates but must be screened for ADPKD

— Imaging by age criteria + genetic testing for definitive exclusion in donors <30

— Donating with undiagnosed ADPKD could harm both donor and recipient — informed consent must be explicit

— Discuss hepatotoxicity risk (~5%), aquaresis affecting daily life (5+ L urine output), cost (~$15,000/month), and monthly LFT requirements

— Shared decision-making — not all eligible patients should start

— Hospital discharge after cyst infection: ensure 4–6 week antibiotic prescription, outpatient nephrology follow-up within 1–2 weeks, repeat imaging in 4–6 weeks

— Tolvaptan continuity — REMS lapses lead to dispensing failures; document each LFT review

— Pregnancy planning — medication switches (ACEi → labetalol; stop tolvaptan) before conception

— Driver licensing for patients with known intracranial aneurysm or post-SAH — variable by state; commercial drivers may have reporting requirements

— Pilots, public safety personnel — occupational health must be informed; this can justify earlier aneurysm screening

— Preimplantation genetic diagnosis is legally and ethically permissible; counseling should be non-directive

— Prenatal testing with potential pregnancy termination — religious and personal values must be respected

— Patients should be encouraged but not coerced to share diagnosis with family

— Physician cannot directly contact relatives without consent — provide patient with letter templates

Predictive genetic testing in minors:

Genetic Information Nondiscrimination Act (GINA):

Living-related kidney donation:

Informed consent for tolvaptan:

Transitions of care risk points:

Mandatory considerations:

Reproductive ethics:

Disclosure to at-risk relatives:

CCS pearl: When a 19-year-old asymptomatic child of an ADPKD patient requests genetic testing "to know," the right answer involves genetic counseling referral first — discussing GINA limitations, insurance implications for life/disability policies, and reproductive considerations — before ordering the test. Don't order PKD1/PKD2 sequencing reflexively at the first visit.

High-Yield Associations and Rapid-Fire Facts

— PKD1 (chromosome 16) — 78%, severe, ESRD ~55

— PKD2 (chromosome 4) — 15%, mild, ESRD ~70

— PKHD1 — ARPKD (recessive, pediatric)

— Age 15–39: ≥3 cysts

— Age 40–59: ≥2 per kidney

— Age ≥60: ≥4 per kidney

— Liver cysts (>80%)

— Intracranial aneurysms (9–12%)

— Mitral valve prolapse (25%)

— Colonic diverticulosis

— Inguinal/abdominal hernias

— Seminal vesicle cysts

— Intensive BP target <110/75 in young low-risk ADPKD slowed TKV growth and reduced LVH

— Dual RAAS blockade showed no benefit

Genetics quick-recall:

Ravine ultrasound criteria (positive family history):

Extrarenal "checklist":

Tolvaptan triad to remember: aquaresis, hepatotoxicity (REMS LFTs), eGFR ≥25 requirement.

Antibiotics that penetrate cysts (lipophilic): fluoroquinolones, TMP-SMX, clindamycin, chloramphenicol, metronidazole. Aminoglycosides and beta-lactams do not penetrate.

Most common stone type: uric acid (low urine pH) — treat with potassium citrate.

HALT-PKD trial:

TEMPO 3:4 trial: tolvaptan slowed eGFR decline by ~1 mL/min/year and TKV growth.

REPRISE trial: tolvaptan effective even at eGFR 25–65.

Major causes of death in ADPKD: cardiovascular (not ESRD).

Mayo Imaging Classification: Class 1C/1D/1E = rapid progressors → tolvaptan candidates.

Hepatic cyst predilection: female, multiparity, estrogen exposure — avoid estrogens.

Aneurysm screening modality: non-contrast MRA (preserves renal function).

Aneurysm intervention threshold: ≥7 mm, posterior circulation, growing, symptomatic, prior SAH.

Vaccine to remember at diagnosis: hepatitis B (high-dose).

Pregnancy switch: ACEi → labetalol or nifedipine; stop tolvaptan with contraception.

Pediatric ADPKD management: annual BP screening from age 5, defer imaging/genetic testing.

Board pearl: "Adult + bilateral enlarged kidneys + hypertension + family history of brain bleed" → ADPKD with intracranial aneurysm risk. "Infant + oligohydramnios + bilateral echogenic kidneys + hepatic fibrosis" → ARPKD. These two stems alternate frequently on Step 3 — kidney size and age separate them instantly.

Board Question Stem Patterns

— 35-year-old with HTN, palpable flank masses, mother on dialysis. Best next test? → Renal ultrasound (not CT, not genetic testing first).

— ADPKD patient with htTKV 950 mL/m, eGFR 65, Mayo Class 1D, age 38. Most appropriate disease-modifying therapy? → Tolvaptan with REMS enrollment and monthly LFTs.

— Afebrile flank pain + gross hematuria, self-limited → cyst hemorrhage, supportive care.

— Febrile flank pain, negative urine culture → cyst infection, ciprofloxacin × 4–6 weeks.

— Sudden severe headache, neck stiffness → non-contrast CT head STAT, neurosurgery consult; if CT negative and suspicion high → LP for xanthochromia.

— ADPKD patient + family history of SAH or aneurysm → screening MRA without contrast. Universal screening = wrong answer.

— ADPKD patient planning pregnancy on lisinopril and tolvaptan → switch lisinopril to labetalol or nifedipine, discontinue tolvaptan, ensure contraception during transition.

— 30-year-old ADPKD, eGFR 80, low CV risk → target <110/75.

— Sister of ADPKD patient wishes to donate at age 28 → renal ultrasound + genetic testing before approval.

— Young adult with HTN but normal kidney ultrasound and no family history → not ADPKD; workup secondary hypertension (renin/aldosterone, metanephrines, renal Dopplers).

— Patient with hypernatremia (not hyponatremia) on tolvaptan from inadequate water intake → counsel on free water access, consider dose reduction.

— Asymptomatic 8-year-old child of ADPKD parent → annual BP screening, defer imaging and genetic testing; refer for genetic counseling at family request.

— eGFR declining to 28, asymptomatic → refer to transplant clinic now; preemptive transplant superior to dialysis-then-transplant.

Stem 1 — Classic diagnosis:

Stem 2 — Tolvaptan eligibility:

Stem 3 — Cyst hemorrhage vs infection:

Stem 4 — Thunderclap headache in ADPKD:

Stem 5 — Aneurysm screening indication:

Stem 6 — Pregnancy management:

Stem 7 — BP target:

Stem 8 — Living donor screening:

Stem 9 — Differential trap:

Stem 10 — Hyponatremia on tolvaptan:

Stem 11 — Pediatric question:

Stem 12 — Transplant timing:

Step 3 management: Recognize the complication-class stem by its prompts: "afebrile + hematuria" vs "febrile + negative culture" vs "thunderclap headache." Each maps to a discrete management algorithm — memorize the one-line response for each, and you'll convert these stems quickly without second-guessing.

One-Line Recap

ADPKD is an autosomal dominant systemic ciliopathy requiring lifelong surveillance focused on early hypertension control to <110/75 in young low-risk patients, risk stratification by Mayo Imaging Classification to identify rapid progressors who benefit from tolvaptan, vigilance for cyst hemorrhage versus infection (lipophilic antibiotics for the latter), targeted intracranial aneurysm screening with MRA in those with family history of SAH or high-risk occupation, and proactive transplant preparation including hepatitis B vaccination starting at eGFR <30.

Diagnosis: Ravine ultrasound criteria by age + family history; reserve MRI for TKV in rapid progressors and genetic testing for equivocal cases.

Disease-modifying therapy: Tolvaptan for Mayo Class 1C–1E or eGFR decline ≥3 mL/min/year, eGFR ≥25, with REMS-mandated monthly LFTs × 18 months then q3 months; counsel on aquaresis and hepatotoxicity.

Complications mnemonic: Hypertension, Hemorrhage (afebrile), Infection (febrile, lipophilic abx), Stones (uric acid → potassium citrate), Aneurysms (≥7 mm or symptomatic → intervention), Liver cysts (avoid estrogens), Valves (MVP, AR).

Foundational care: ACEi/ARB monotherapy, 3 L/day water, low sodium, moderate protein, statin per ASCVD risk, hepatitis B vaccination early, transplant referral at eGFR ≤30, pregnancy planning with medication switches preconception, and genetic counseling with GINA discussion before predictive testing.

Board pearl: When in doubt between testing strategies, choose ultrasound first, MRA for aneurysm screening only when indicated, and tolvaptan only for rapid progressors with REMS infrastructure in place — over-testing is as wrong as under-treating on Step 3 ADPKD stems, and the correct answer always reflects guideline-directed, patient-tailored, longitudinal management rather than reflexive intervention.