Immune System

Solid organ transplant: immunosuppression and complications

Clinical Overview and When to Suspect Transplant Complications

— Any new symptom in a SOT recipient is a transplant problem until proven otherwise — do not anchor on community diagnoses.

— Fever: think infection (CMV, BK, PJP, bacterial, fungal) vs rejection vs drug fever vs PTLD.

— Graft dysfunction (↑Cr in kidney, ↑LFTs in liver, hypoxia in lung, ↓EF in heart): rejection, drug toxicity (CNI), infection, recurrent disease, vascular/anastomotic.

— GI symptoms: CMV colitis, mycophenolate toxicity, C. difficile.

— Skin lesions: squamous cell carcinoma (200×↑), Kaposi sarcoma, fungal.

— <1 month: nosocomial/donor-derived infection, surgical/anastomotic complication, early acute rejection.

— 1–6 months: opportunistic infections (CMV, PJP, BK, EBV, Nocardia, Aspergillus, reactivated TB/HSV), acute rejection.

— >6 months: community-acquired infection, late CMV, chronic rejection, PTLD, malignancy, recurrent native disease.

Board pearl: A SOT recipient with fever and any new symptom 1–6 months post-transplant = assume opportunistic infection AND check CMV PCR + drug levels before reflexively treating with empiric antibiotics alone.

Step 3 management: Always confirm the transplant date, induction agent, current maintenance regimen, prophylaxis (TMP-SMX, valganciclovir), recent rejection episodes, and most recent drug troughs before ordering anything else.

Scope: Solid organ transplant (SOT) recipients — kidney, liver, heart, lung, pancreas, intestine — require lifelong immunosuppression balanced against rejection, infection, malignancy, and drug toxicity.

Who you see on Step 3: ambulatory recipient with fever, rising creatinine, GI symptoms, new pulmonary infiltrate, or abnormal LFTs; perioperative recipient needing non-transplant surgery; transplant candidate on the waitlist.

When to suspect a transplant complication:

Time-since-transplant framework drives differential:

Net state of immunosuppression depends on agents, doses, recency of induction/anti-rejection treatment, leukopenia, uremia, hyperglycemia, viral coinfection, and prophylaxis adherence.

Presentation Patterns and Key History

— Organ transplanted, date of transplant, donor type (deceased/living, CMV/EBV serostatus mismatch).

— Induction agent (basiliximab vs anti-thymocyte globulin/ATG vs alemtuzumab).

— Current maintenance triple therapy (CNI + antimetabolite + steroid is standard).

— Rejection history and treatment (pulsed steroids, ATG → ↑↑ infection risk for 6–12 months).

— Prophylaxis: TMP-SMX (PJP, Nocardia, Toxoplasma, UTI) usually 6–12 months; valganciclovir for CMV (especially D+/R−) 3–6 months; antifungal in lung/liver.

— Adherence, recent drug level trends, recent dose changes, new medications (interactions).

— Vaccination status (no live vaccines post-transplant), travel, exposures, pets, gardening.

— Febrile illness: cough → CMV pneumonitis, PJP, bacterial, Aspergillus; dysuria → BK virus or bacterial UTI (kidney); diarrhea → CMV colitis, C. diff, MMF toxicity.

— Asymptomatic lab abnormality: rising creatinine in renal recipient → rule out rejection, CNI toxicity, BK nephropathy, dehydration, obstruction.

— Neurologic: headache + fever → cryptococcus, listeria, toxoplasma, PML; tremor → tacrolimus toxicity.

— Cutaneous: ulcerating papules → Nocardia, fungal; verrucous/scaly → HPV-driven SCC.

— ↑ Levels: azoles (fluconazole, voriconazole), macrolides (clarithromycin, erythromycin), diltiazem, verapamil, grapefruit.

— ↓ Levels: rifampin, phenytoin, carbamazepine, St. John's wort.

Key distinction: CNI nephrotoxicity typically shows high tacrolimus trough, bland urine, slow Cr rise, often with tremor/HTN/hyperK, whereas acute rejection shows variable trough, sometimes pyuria/proteinuria, faster Cr rise — biopsy distinguishes definitively.

Board pearl: A kidney transplant patient started on clarithromycin for sinusitis who then develops AKI and tremor has tacrolimus toxicity until proven otherwise — check level urgently.

Targeted SOT history must be obtained in every encounter:

Common presenting syndromes:

Drug-interaction red flags (CNI metabolized by CYP3A4):

Physical Exam Findings and Graft Assessment

— Fever may be blunted by steroids and CNIs — even low-grade fever (37.5–38°C) is meaningful.

— Hypertension is near-universal (CNI, steroids); track trend.

— Weight gain (steroids, edema), cushingoid features, proximal weakness.

— Kidney (iliac fossa allograft): palpate for tenderness or new bruit; assess JVP, edema, urine output. Tenderness over graft → rejection, pyelonephritis, obstruction, urinoma.

— Liver (RUQ): tenderness, hepatomegaly, ascites, jaundice → rejection, hepatic artery thrombosis, biliary stricture, recurrent disease.

— Heart: listen for new S3, rales, JVD; denervated heart does not produce angina — silent ischemia from cardiac allograft vasculopathy (CAV) is the rule.

— Lung: spirometry trend (FEV1 drop ≥10% suggests acute rejection or bronchiolitis obliterans syndrome/BOS); auscultate for crackles, decreased breath sounds at incision.

— Pancreas: hyperglycemia recurrence, abdominal tenderness over graft, hematuria (bladder-drained grafts).

— Actinic keratoses, SCC (most common malignancy post-SOT), BCC, melanoma, Kaposi (HHV-8), warts (HPV).

— Oral: thrush, hairy leukoplakia, gingival hyperplasia (cyclosporine), Kaposi.

— Tacrolimus/cyclosporine: tremor, HTN, hirsutism (CsA), gingival hyperplasia (CsA), alopecia (Tac).

— Steroids: cushingoid, striae, proximal myopathy, cataracts.

— mTOR inhibitors (sirolimus, everolimus): mouth ulcers, peripheral edema, poor wound healing.

— MMF: pallor (anemia), bruising (cytopenias).

Step 3 management: Document graft tenderness, BP, weight, skin survey, and any neurologic findings at every transplant follow-up — these drive the order set more than any single lab.

Board pearl: A heart transplant recipient with dyspnea on exertion and no chest pain but a positive stress test likely has cardiac allograft vasculopathy — proceed to coronary angiography or intravascular ultrasound.

General appearance and vitals in any SOT visit:

Graft-specific exam:

Skin head-to-toe at every visit:

Drug-toxicity signs:

Diagnostic Workup — Initial Labs, Imaging, and Drug Levels

— CBC with diff (leukopenia from MMF, valganciclovir, CMV, ATG aftermath).

— CMP: Cr trend vs baseline, K+ (CNI causes hyperK + RTA type 4), Mg (CNI wasting), glucose (PTDM/NODAT), LFTs.

— Urinalysis with micro + urine protein/Cr ratio; urine culture in kidney recipients.

— CNI trough level (tacrolimus drawn immediately before next dose) — interpret in context of target window for organ and time since transplant.

— Lactate, blood cultures, CRP/procalcitonin if febrile.

— CMV PCR (quantitative whole blood/plasma) — workhorse test; rising copies = viremia → consider preemptive therapy or end-organ disease workup.

— BK virus PCR in kidney recipients with ↑Cr or routine surveillance — plasma BK >10,000 copies/mL suggests BK nephropathy.

— EBV PCR — rising titers raise concern for PTLD.

— Respiratory viral panel; SARS-CoV-2.

— Kidney: duplex ultrasound — assess hydronephrosis, perinephric collection (lymphocele, urinoma, hematoma), resistive indices, vascular patency.

— Liver: Doppler US for hepatic artery thrombosis (early), portal vein, biliary dilation; MRCP for strictures.

— Heart: echo for wall motion, EF, pericardial effusion; annual coronary surveillance.

— Lung: CXR, then HRCT; spirometry trends.

— Fever + pulmonary: CT chest, sputum/BAL with PJP DFA, galactomannan, fungal cultures, AFB, CMV.

— Diarrhea: C. diff PCR, stool studies, CMV PCR, consider colonoscopy with biopsy if CMV suspected.

Step 3 management: Order CMV PCR, BK PCR (if kidney), CBC, CMP, tacrolimus trough, UA, and graft Doppler ultrasound as the reflexive starter panel for unexplained graft dysfunction in the first year.

CCS pearl: Advance the clock only after sending drug troughs and viral PCRs — these results redirect management within 24 hours.

Baseline labs at every concerning visit:

Viral surveillance / targeted PCRs:

Imaging — graft-specific:

Infectious workup tailored by time and syndrome:

Diagnostic Workup — Confirmatory Studies and Biopsy

— Kidney: ultrasound-guided percutaneous biopsy; Banff classification grades acute T-cell-mediated rejection (TCMR) (tubulitis, interstitial inflammation) and antibody-mediated rejection (AMR) (peritubular capillaritis, C4d staining, donor-specific antibodies/DSA).

— Liver: percutaneous or transjugular; portal lymphocytic infiltrate, bile duct damage, endothelialitis = the classic rejection triad.

— Heart: surveillance endomyocardial biopsy via right IJ — ISHLT grading (0R, 1R, 2R, 3R); gene-expression profiling (AlloMap) can defer biopsy in low-risk stable patients >6 months out.

— Lung: transbronchial biopsy with BAL.

— Send when AMR suspected or surveillance per program — class I/II HLA antibodies; complement-binding (C1q) subset adds prognostic info.

— CMV tissue-invasive disease: tissue biopsy showing inclusions ("owl's eye") + immunohistochemistry; PCR alone insufficient for organ-invasive diagnosis.

— PJP: BAL with DFA/PCR; serum β-D-glucan supportive but not specific.

— Aspergillus: serum/BAL galactomannan, β-D-glucan, culture, biopsy.

— PTLD: tissue biopsy of mass/lymphadenopathy with EBER in situ hybridization — EBV-driven monomorphic B-cell lymphoma most common.

— Annual or biennial coronary angiography ± intravascular ultrasound (IVUS) — IVUS detects diffuse intimal thickening that angiography misses.

Key distinction: CMV viremia (PCR+) without organ symptoms is treated preemptively (oral valganciclovir), but CMV tissue-invasive disease (colitis, pneumonitis, retinitis) requires tissue confirmation and IV ganciclovir plus reduction of immunosuppression.

Board pearl: A kidney recipient with rising Cr, donor-specific antibodies, and C4d+ peritubular capillaries on biopsy = antibody-mediated rejection → plasmapheresis + IVIG ± rituximab, not just pulse steroids.

Allograft biopsy is the gold standard for distinguishing rejection from other causes of graft dysfunction:

Donor-specific antibodies (DSA):

Specialized infectious confirmation:

Cardiac allograft vasculopathy (CAV):

Risk Stratification and Management Logic for Rejection vs Infection

— Is this rejection (under-immunosuppressed) or infection/toxicity (over-immunosuppressed)?

— Wrong direction = catastrophic. Always biopsy or culture before reflexively pulsing steroids when feasible.

— Recent dose reduction or non-adherence.

— Subtherapeutic CNI trough.

— Recent infection treated with reduced immunosuppression.

— Sensitized recipient (prior transplant, transfusions, pregnancies → preformed DSA).

— Early post-transplant period or recent steroid taper.

— Supratherapeutic trough (interacting drug recently added).

— Recent intensified immunosuppression (treated rejection in past 3–6 months).

— Missed prophylaxis doses.

— Donor CMV+/recipient CMV− mismatch (highest CMV risk).

— Leukopenia preceding event.

— Mild TCMR (Banff IA/IB) → pulse methylprednisolone (e.g., 250–500 mg IV ×3 days).

— Severe/steroid-resistant TCMR (Banff II/III) → anti-thymocyte globulin (ATG).

— AMR → plasmapheresis + IVIG ± rituximab ± bortezomib; sometimes eculizumab.

Step 3 management: When in doubt with graft dysfunction → biopsy the graft. Empiric steroid pulses without tissue diagnosis is a common wrong-answer trap on Step 3 unless biopsy is contraindicated or unavailable.

Board pearl: Reducing immunosuppression is itself a therapeutic intervention — for BK nephropathy, PTLD, and severe opportunistic infection it is the first move, not adjunctive.

The central Step 3 decision in any unwell transplant patient:

Pretest probability factors favoring rejection:

Factors favoring infection/toxicity:

Rejection severity grading guides therapy:

Infection severity: sepsis criteria, end-organ involvement, neutrophil count drive ICU vs ward and empiric breadth (cover Pseudomonas, MRSA, plus opportunistic if 1–6 month window).

Reduce immunosuppression when serious infection or PTLD: typically stop antimetabolite (MMF) first, reduce CNI second, maintain low-dose steroid; coordinate with transplant team.

Pharmacotherapy — Maintenance Immunosuppression Regimens

— Calcineurin inhibitor (CNI): tacrolimus (preferred, ~95% of regimens) or cyclosporine.

— Antimetabolite: mycophenolate mofetil (MMF) or mycophenolic acid; azathioprine in select cases (pregnancy).

— Corticosteroid: prednisone, often tapered to 5 mg/day or withdrawn in low-risk patients.

— Mechanism: binds FKBP-12, inhibits calcineurin → blocks IL-2 transcription → T-cell suppression.

— Trough targets: 8–12 ng/mL early, 5–8 ng/mL maintenance (program-specific).

— Toxicities: nephrotoxicity, neurotoxicity (tremor, headache, seizure, PRES), hyperK, hypoMg, HTN, post-transplant diabetes (PTDM), alopecia, QT prolongation.

— CYP3A4 substrate — major drug interactions (azoles ↑, rifampin ↓).

— Inhibits IMPDH → blocks de novo purine synthesis (lymphocyte-selective).

— Toxicities: GI (diarrhea, gastritis), leukopenia, anemia, teratogenic (REMS, contraception required).

— Hold/reduce in infection or cytopenia.

— Used to spare CNI (in CNI nephrotoxicity) or for anti-proliferative/anti-malignancy effect.

— Toxicities: impaired wound healing (avoid perioperatively), proteinuria, hyperlipidemia, mouth ulcers, pneumonitis, cytopenias.

Key distinction: Tacrolimus = diabetes + neurotox + alopecia; cyclosporine = gums + hair + lipids. Both cause nephrotoxicity, HTN, hyperK, hypoMg.

Board pearl: Always check CYP3A4 interactions before adding any new drug — clarithromycin, fluconazole, diltiazem, and grapefruit are the classic exam triggers for tacrolimus toxicity.

Standard maintenance triple therapy (most adult SOT recipients):

Tacrolimus:

Cyclosporine: similar mechanism via cyclophilin; gingival hyperplasia, hirsutism, hyperlipidemia more than tacrolimus; less diabetogenic.

Mycophenolate (MMF):

Azathioprine: purine analog; pretest TPMT activity to avoid catastrophic myelosuppression; avoid concomitant allopurinol (or reduce aza by 75%).

mTOR inhibitors (sirolimus, everolimus):

Belatacept: IV CTLA-4-Ig, monthly; CNI-sparing; contraindicated in EBV-seronegative recipients (PTLD risk).

Steroids: hyperglycemia, osteoporosis, cataracts, weight gain, mood, infection.

Induction Agents, Prophylaxis, and Vaccination Pharmacology

— Basiliximab (anti-CD25/IL-2R): non-depleting; lower-risk standard immunologic recipient.

— Anti-thymocyte globulin (ATG, Thymoglobulin): T-cell depleting; high-risk (sensitized, repeat transplant, deceased donor) or steroid-avoidance protocols; risks: cytokine release, serum sickness, prolonged lymphopenia, ↑↑ CMV/PTLD.

— Alemtuzumab (anti-CD52): profound, prolonged depletion.

— TMP-SMX: PJP, Toxoplasma, Nocardia, Listeria, UTI prevention — 6–12 months minimum, often lifelong in lung/heart.

— Valganciclovir: CMV prophylaxis 3–6 months (longer in D+/R− or lung). Alternative = preemptive monitoring with weekly CMV PCR and treat at threshold.

— Nystatin or clotrimazole: oral candidiasis, 1–3 months.

— Antifungal (voriconazole, posaconazole, or itraconazole): lung and some liver recipients; major CNI interaction — reduce tacrolimus dose ~50–75% when starting an azole.

— Isoniazid ×9 months if latent TB (positive IGRA pre-transplant).

— HBV reactivation prophylaxis (entecavir/tenofovir) if HBsAg+ or core+.

— Pre-transplant: complete all live vaccines (MMR, varicella, zoster live, yellow fever) — must be ≥4 weeks before transplant.

— Post-transplant: NO live vaccines ever. Give inactivated annually: influenza (inactivated), pneumococcal (PCV20 or PCV15→PPSV23), Tdap, HPV, hepatitis B, recombinant zoster (Shingrix — non-live, safe and recommended), COVID-19.

— Avoid live vaccines in household contacts when possible (e.g., oral polio, smallpox); MMR and varicella in contacts are acceptable.

— TCMR → high-dose methylprednisolone pulse, then ATG if steroid-resistant.

— AMR → plasmapheresis + IVIG ± rituximab; complement inhibition (eculizumab) for severe.

Step 3 management: A transplant recipient asking about the shingles vaccine → give Shingrix (recombinant, non-live); never the live Zostavax.

Board pearl: TMP-SMX prophylaxis prevents four bugs: PJP, Toxo, Nocardia, Listeria. If discontinued, all four reemerge as boards differentials.

Induction immunosuppression (given at transplant, before/with maintenance):

Antimicrobial prophylaxis (high-yield on Step 3):

Vaccinations:

Anti-rejection therapy refresher:

Special Populations — Elderly and Renal/Hepatic Impairment

— Growing waitlist population; lower acute rejection rates but higher infection and malignancy mortality.

— Reduced immunosuppression intensity is often appropriate — lower CNI troughs, steroid avoidance/minimization, careful MMF dosing.

— Polypharmacy: review every new drug for CYP3A4 interactions; deprescribe when possible.

— Aggressive cardiovascular risk reduction (statin, BP, glycemic control); fall and fracture prevention (bone density q1–2 years, vitamin D, bisphosphonate if osteoporotic).

— CNI nephrotoxicity is dose-dependent and time-dependent — up to 20% of heart/liver/lung recipients develop CKD stage 4–5 within 5–10 years.

— Strategies: CNI minimization, mTOR conversion (sirolimus/everolimus), or belatacept (in kidney recipients).

— Avoid NSAIDs, IV contrast when possible, aminoglycosides.

— Adjust MMF and antiviral doses (valganciclovir is heavily renally cleared — under-dosing → CMV breakthrough; over-dosing → cytopenias).

— Tacrolimus and cyclosporine are hepatically metabolized — reduce dose 25–50% in Child-Pugh B/C and monitor troughs closely.

— MMF clearance is altered; monitor cytopenias.

— Hepatic artery thrombosis, biliary stricture, and recurrent hepatitis C/HBV/PSC/PBC/NASH all cause graft dysfunction.

— Valganciclovir: renal-adjusted by CrCl, dialyzed.

— TMP-SMX: dose-adjust at CrCl <30; can worsen hyperkalemia with CNI.

— Sirolimus: avoid in significant proteinuria (>1 g/day).

Key distinction: CKD in non-kidney SOT recipient is usually multifactorial — pre-existing disease + CNI toxicity + perioperative AKI + hypertension + diabetes — not a single reversible cause.

Step 3 management: When CNI nephrotoxicity is established (rising Cr, supratherapeutic troughs, no rejection on biopsy) → CNI dose reduction, switch to mTOR-based regimen, or belatacept conversion in coordination with transplant nephrology.

Elderly recipients (≥65):

Renal impairment in non-kidney recipients:

Hepatic impairment:

Drug-dose adjustment cheat sheet:

Special Populations — Pregnancy and Pediatric Considerations

— Generally safe ≥1 year post-transplant with stable graft function (Cr <1.5, minimal proteinuria, no recent rejection, BP controlled, low-dose immunosuppression).

— Counsel before conception about teratogenicity and contraception.

— SAFE: tacrolimus, cyclosporine, azathioprine (yes, despite Category D label — used historically and considered acceptable), low-dose prednisone.

— CONTRAINDICATED: mycophenolate (MMF/MPA) — major teratogen (cleft lip/palate, microtia, cardiac defects, miscarriage); switch to azathioprine at least 6 weeks before conception. REMS program requires contraception counseling.

— mTOR inhibitors (sirolimus, everolimus): avoid — inadequate data, animal teratogenicity.

— Belatacept: avoid in pregnancy (insufficient data).

— Higher rates of preeclampsia, preterm delivery, IUGR, gestational diabetes, hypertension.

— Distinguishing preeclampsia vs rejection vs CNI toxicity in a kidney transplant recipient is difficult — requires multidisciplinary team.

— Drug troughs change as volume of distribution increases; monitor every 2–4 weeks.

— Growth retardation from steroids — steroid-minimization protocols favored.

— EBV-naïve at higher PTLD risk (most kids are EBV− pre-transplant) — monitor EBV PCR closely.

— Vaccination catch-up critical pre-transplant; live vaccines off the table afterward.

— Adolescent non-adherence is the leading cause of late graft loss — transition-of-care programs essential.

Board pearl: A transplant recipient planning pregnancy on MMF → switch to azathioprine at least 6 weeks before conception and reconfirm stable graft function. MMF in early pregnancy = high-yield exam pitfall.

Step 3 management: Pediatric/adolescent transplant patients need structured adherence assessment at every visit, school re-entry plans, and a formal transition-to-adult-care program by mid-adolescence.

Pregnancy after transplant:

Immunosuppression in pregnancy:

Pregnancy complications:

Breastfeeding: Tacrolimus, cyclosporine, prednisone, and azathioprine are present in breast milk in low concentrations; many programs now permit breastfeeding with monitoring — individualize.

Pediatric recipients:

Complications — Infection, Malignancy, Metabolic, and Cardiovascular

— CMV disease: fever, leukopenia, transaminitis, colitis, pneumonitis, retinitis — treat IV ganciclovir → step down to valganciclovir; reduce immunosuppression; ganciclovir-resistant → foscarnet or letermovir/maribavir.

— BK virus nephropathy: rising Cr, plasma BK PCR >10,000, biopsy with viral inclusions/SV40 staining — primary therapy is reduction of immunosuppression, not antivirals.

— PJP pneumonia: bilateral GGO on CT, hypoxia out of proportion, ↑LDH; treat high-dose TMP-SMX + steroids if PaO2 <70.

— Aspergillus: voriconazole (huge CNI interaction).

— Cryptococcus: meningitis or pulmonary; LP, induction with amphotericin + flucytosine then fluconazole.

— Skin cancer: SCC > BCC; aggressive surveillance, sunscreen, voriconazole avoidance long-term.

— PTLD: EBV-driven B-cell lymphoproliferation; treatment = reduce immunosuppression first, then rituximab ± CHOP.

— Kaposi sarcoma (HHV-8), anogenital cancers (HPV), renal cell, hepatocellular (recurrent HCV/NASH).

— Post-transplant diabetes mellitus (PTDM/NODAT): tacrolimus > cyclosporine, steroids, sirolimus; screen with HbA1c at 3, 6, 12 months.

— Dyslipidemia: sirolimus, cyclosporine, steroids — statins indicated; pravastatin/rosuvastatin preferred (less CYP3A4 interaction).

— Hypertension: CNI, steroids — CCB (amlodipine) often first-line; avoid diltiazem/verapamil unless intentional tacro-sparing.

— Osteoporosis: steroid-driven; DEXA, vitamin D, bisphosphonate.

Key distinction: PTLD treatment starts with reducing immunosuppression, not chemotherapy. Rituximab added for CD20+ B-cell PTLD; chemotherapy reserved for aggressive/refractory disease.

Board pearl: In a kidney recipient with rising Cr and plasma BK virus PCR >10,000 copies/mL, the correct answer is reduce immunosuppression (usually MMF first), not start an antiviral — there is no proven effective antiviral for BK.

Infectious complications by timeline (recap with depth):

Malignancy (the long-game killer):

Metabolic complications:

Cardiovascular disease: leading cause of death in kidney transplant recipients with functioning graft.

When to Escalate Care — ICU, Consult, Inpatient Triage

— Suspected acute rejection.

— Hemodynamic instability.

— Suspected hepatic artery thrombosis, vascular anastomotic emergency.

— Severe opportunistic infection.

— Need for biopsy or specialized immunosuppression management.

— Fever >38°C without clear outpatient-manageable source.

— Acute graft dysfunction (rising Cr by ≥25% from baseline, new transaminitis, hypoxia, EF drop).

— Neutropenia <1000 with fever.

— New seizure, focal neurologic deficit, altered mentation.

— Unable to tolerate oral intake (can't take oral immunosuppression reliably).

— Severe drug toxicity (tacrolimus level >20, PRES, severe AKI).

— Septic shock, severe ARDS, respiratory failure, large hemoptysis.

— Severe acute rejection with hemodynamic compromise (cardiac/lung).

— PRES with seizures.

— Cytokine release syndrome after ATG.

— Plasmapheresis/CRRT need.

— Transplant medicine/surgery for all admissions.

— Infectious disease for opportunistic infection, complex antimicrobials.

— Nephrology if not transplant nephrology already involved (CRRT, plasmapheresis).

— Hematology/oncology for PTLD or post-transplant malignancy.

— Pharmacy for drug-interaction reconciliation — high-impact, low-friction consult.

— Continue immunosuppression through the day of surgery (use IV equivalents if NPO prolonged).

— Stress-dose steroids if on chronic prednisone ≥5 mg.

— Hold mTOR inhibitors ≥1–2 weeks pre-op (wound healing).

CCS pearl: In any unstable SOT patient, your first three orders are typically vitals + monitor, IV access + labs (including drug trough, CMV/BK PCR), and CALL TRANSPLANT TEAM. The consult itself counts as a high-yield action.

Step 3 management: A transplant patient on chronic prednisone going to OR for cholecystectomy → stress-dose hydrocortisone 50–100 mg IV at induction plus continued maintenance regimen.

Always loop in the transplant center — even if the patient presents to an outside hospital. Transfer threshold should be low for:

Inpatient admission criteria:

ICU triage:

Consults required:

Perioperative for non-transplant surgery:

Key Differentials — Causes Within the Transplant Category

— Acute T-cell-mediated rejection (TCMR): ↑Cr/LFTs, biopsy shows tubulitis/interstitial inflammation (kidney) or endothelialitis (liver); treat pulse steroids ± ATG.

— Acute antibody-mediated rejection (AMR): DSA+, C4d+ staining, microvascular inflammation; treat plasmapheresis + IVIG ± rituximab.

— Chronic rejection / chronic allograft dysfunction: indolent decline, fibrosis on biopsy — limited therapy, optimize.

– Kidney: interstitial fibrosis and tubular atrophy (IFTA), transplant glomerulopathy.

– Liver: vanishing bile duct syndrome.

– Heart: cardiac allograft vasculopathy (CAV).

– Lung: bronchiolitis obliterans syndrome (BOS).

— CNI nephrotoxicity: supratherapeutic trough, bland UA, often with tremor, hyperK, hypoMg.

— BK virus nephropathy (kidney): viral inclusions, SV40+, plasma BK PCR high; treat by reducing IS.

— Recurrent native disease in the graft:

– FSGS recurrence (can recur within hours-days, massive proteinuria).

– IgA nephropathy, MPGN, oxalosis.

– Hepatitis B/C recurrence in liver (much improved with DAAs).

– PSC, PBC, autoimmune hepatitis recurrence.

— De novo disease: e.g., transplant glomerulopathy, de novo DSA-driven AMR.

— Mechanical/surgical:

– Kidney: ureteral stenosis, urinoma, lymphocele compressing ureter, renal artery stenosis (late HTN + AKI with ACEi).

– Liver: hepatic artery thrombosis (early catastrophic), biliary stricture, portal vein thrombosis.

– Heart: tamponade, rejection-induced HF.

– Lung: anastomotic dehiscence, airway stricture.

Key distinction: Transplant renal artery stenosis classically presents with refractory hypertension + AKI when an ACEi/ARB is started + a bruit over the graft — diagnose with Doppler US, confirm with angiography.

Board pearl: FSGS can recur within hours of kidney transplant with nephrotic-range proteinuria; treatment is plasmapheresis and sometimes rituximab — a classic boards image.

For any acute graft dysfunction, run this same-category differential:

Key Differentials — Non-Transplant Causes to Not Miss

— Prerenal AKI: dehydration, GI losses, diuretics + ACEi/ARB + NSAID — common in outpatient transplant recipients.

— Obstructive uropathy: BPH, stones, ureteral stricture — get ultrasound.

— Sepsis from any source: UTI, pneumonia, line infection, intra-abdominal.

— Drug-induced AKI: NSAIDs, IV contrast, aminoglycosides, vancomycin troughs, TMP-SMX-induced pseudo-creatinine elevation (inhibits tubular secretion — ↑Cr without true GFR drop).

— Cardiorenal syndrome, hepatorenal syndrome.

— Community-acquired pneumonia, viral (influenza, RSV, SARS-CoV-2).

— Drug-induced pneumonitis (sirolimus, everolimus).

— Pulmonary edema, ARDS, PE.

— Alveolar hemorrhage (post-procedure).

— C. difficile (overuse of antibiotics + immunosuppression = high risk).

— IBD-like inflammation, NSAID enteropathy.

— Mycophenolate-induced colitis (can mimic IBD or CMV histologically).

— Cholelithiasis (cyclosporine increases stones).

— Stroke, intracranial hemorrhage (especially on antiplatelets/anticoagulants).

— Metabolic encephalopathy (hyponatremia, uremia, hepatic).

— PRES (posterior reversible encephalopathy syndrome): HTN + seizure + visual changes + parieto-occipital edema on MRI — classic with tacrolimus/cyclosporine.

— Migraine, medication side effect.

— MMF, valganciclovir, TMP-SMX, parvovirus B19 (pure red cell aplasia), CMV, HUS/TMA from CNI.

Key distinction: TMP-SMX raises serum creatinine ~10–20% without true GFR change (blocks tubular secretion of creatinine) — recognize this on Step 3 to avoid unnecessary biopsy.

Board pearl: Tacrolimus + HTN + headache + seizure + bilateral parieto-occipital T2 hyperintensity on MRI = PRES — stop or reduce tacrolimus and treat HTN aggressively; usually reversible.

Just because they're transplanted doesn't mean it's the transplant: keep general medicine differentials live.

Pulmonary infiltrate differentials:

GI symptoms:

Neurologic:

Hematologic cytopenias:

Secondary Prevention and Long-Term Outpatient Plan

— BP target <130/80 in most SOT recipients; CCB (amlodipine) often preferred; ARB/ACEi if proteinuria; avoid sudden ACEi start in suspected transplant RAS.

— Statin in nearly all adult kidney/heart recipients — pravastatin or rosuvastatin preferred (low CYP3A4).

— Aspirin 81 mg for established ASCVD or after careful risk-benefit.

— Smoking cessation mandatory (graft loss, malignancy, cardiac risk).

— Weight, diet, exercise counseling.

— Screen for PTDM at 3, 6, 12 months and annually.

— Metformin if GFR allows; GLP-1 agonists increasingly used; insulin in steroid-induced hyperglycemia.

— Consider lowering tacrolimus or switching to cyclosporine if severe PTDM.

— Skin: annual full-body dermatology exam; daily sunscreen, sun avoidance.

— Colon: same as general population (begin 45) but with low threshold for symptoms.

— Cervical (HPV): annual cytology for women — accelerated from general guidelines.

— Breast, prostate: per general guidelines.

— Liver recipients with HCV/HBV/NASH/cirrhosis history: HCC surveillance with US ± AFP q6 months.

— PTLD: clinical exam + LDH + EBV PCR per program.

Step 3 management: A kidney recipient at 1 year post-transplant should have BP <130/80, LDL with statin, HbA1c monitored, annual derm exam, DEXA, age-appropriate cancer screening, and seasonal inactivated influenza vaccine — these are reliable boards check-the-box items.

Board pearl: Sun protection + dermatology screening = the highest-yield long-term intervention for post-SOT morbidity after the first year.

Cardiovascular prevention (#1 cause of death with functioning graft):

Diabetes management:

Cancer screening (intensified):

Bone health: DEXA at 6–12 months post-transplant and q1–2 years; vitamin D, calcium, bisphosphonate if osteoporotic.

Vaccinations: annual inactivated flu, COVID-19 boosters, pneumococcal, Shingrix, Tdap, HPV — never live.

Medication review: every visit — reconcile, screen for CYP3A4 interactions, ensure prophylaxis appropriate to time post-transplant.

Follow-Up Cadence, Monitoring, and Patient Counseling

— First month: 1–2× per week.

— Months 2–3: weekly to biweekly.

— Months 4–6: every 2–4 weeks.

— Months 7–12: monthly.

— >1 year: every 2–3 months, then every 3–6 months long-term.

— CBC, CMP, CNI trough drawn before AM dose (critical patient counseling: hold morning dose until after blood draw).

— UA + urine protein/Cr in kidney recipients.

— Periodic CMV PCR (especially during/after prophylaxis discontinuation), BK PCR for kidney (monthly ×6 then less frequent), EBV PCR if high-risk.

— HbA1c, lipid panel q3–6 months.

— Drug-specific monitoring (e.g., MMF — CBC for cytopenias).

— Kidney: protein/Cr, BK PCR, eGFR trend.

— Liver: LFTs, MRCP if biliary issues.

— Heart: echo, endomyocardial biopsy (per protocol), annual coronary surveillance for CAV (cath or CT-CA + IVUS).

— Lung: spirometry at every visit — FEV1 drop ≥10% triggers workup for rejection/BOS.

— Medication adherence is non-negotiable — even a few missed doses can precipitate rejection.

— Take tacrolimus on a strict schedule, with consistent food/fasting.

— Avoid grapefruit and grapefruit juice (CYP3A4 inhibition → toxicity).

— Never start any new medication (including OTC, supplements) without checking with transplant team.

— Sick-day plan: when to call (fever, decreased UOP, dyspnea, GI losses).

— Sun protection education.

— Pregnancy/contraception counseling for women of reproductive age.

— Food safety: avoid raw/undercooked meats, unpasteurized dairy, raw sprouts; well water cautions.

CCS pearl: Schedule a transplant clinic follow-up within 1 week of any hospital discharge, and a medication reconciliation within 48–72 hours of any new prescription affecting CYP3A4.

Board pearl: Patient adherence and transitions of care are the leading reversible cause of late graft loss — every visit is a chance to ask, listen, and document.

Outpatient visit cadence (typical, varies by center):

Routine labs at each visit:

Organ-specific surveillance:

Patient counseling priorities:

Ethical, Legal, and Patient Safety Considerations

— UNOS-driven allocation using objective scoring (KDPI/EPTS for kidney, MELD for liver, lung allocation score) — equity vs utility.

— Living donor evaluation: must include independent donor advocate to ensure voluntary consent free of coercion; informed consent details surgical risks, future ESRD risk, financial impact.

— Directed donation, paired exchange ethics.

— Hepatitis C+ donor → HCV− recipient: now offered routinely with post-transplant DAA therapy; requires explicit informed consent about the HCV transmission and treatment plan.

— HIV+ donor → HIV+ recipient (HOPE Act).

— Increased-risk donor (PHS-IRD): disclose donor risk factors and residual window-period transmission risk.

— Pediatric/adolescent recipient transitioning to adult care: re-consent for ongoing immunosuppression and adherence plan.

— Medication reconciliation at every transition of care — the single highest-yield safety intervention; missed prophylaxis or doubled CNI doses are major harm events.

— Look-alike/sound-alike drug names: tacrolimus vs sirolimus, cyclosporine vs cyclophosphamide.

— High-alert medications: CNIs require trough monitoring, REMS-style vigilance.

— No live vaccines — verify with EHR alert before any vaccination order.

— Donor anonymity preserved unless mutual consent for contact.

— Disclosure of HIV/HCV serostatus governed by state law and consent.

— Graft failure with no re-transplant option → goals-of-care conversation, palliative care; dialysis return for kidney recipients.

— Withdrawal of immunosuppression in terminal illness.

Step 3 management: A transplant patient discharged on a new azole for fungal infection → proactively schedule a tacrolimus level within 3–5 days and a clinic call/visit within 1 week — failure to do so is a recognized patient-safety event.

Board pearl: Living donor evaluation requires an independent donor advocate whose sole job is the donor's interest — exam favorite.

Organ allocation ethics:

Informed consent edge cases (high-yield Step 3):

Patient safety priorities:

Confidentiality and disclosure:

End-of-life and futility:

Mandatory reporting: significant adverse events to OPTN; donor-derived disease transmission triggers UNOS reporting.

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: "Tremor + HTN + AKI + new clarithromycin/fluconazole" in a SOT recipient = tacrolimus toxicity until proven otherwise. This stem appears repeatedly in different costumes.

Tacrolimus toxicity = tremor, HTN, hyperK, hypoMg, hyperglycemia (PTDM), neurotoxicity (PRES), alopecia, nephrotoxicity.

Cyclosporine = gingival hyperplasia, hirsutism, hyperlipidemia, nephrotoxicity, HTN.

Mycophenolate = GI side effects, leukopenia, teratogen (REMS).

Sirolimus/everolimus = mouth ulcers, proteinuria, hyperlipidemia, poor wound healing, pneumonitis, no nephrotoxicity directly.

Azathioprine + allopurinol = catastrophic myelosuppression — reduce aza 75% or avoid combo; check TPMT before initiating.

CMV D+/R− = highest risk; treat preemptively or prophylactically with valganciclovir; tissue-invasive disease needs biopsy and IV ganciclovir; resistance → foscarnet or letermovir/maribavir.

BK virus nephropathy = reduce immunosuppression (no proven antiviral).

PTLD = EBV-driven, B-cell; reduce IS → rituximab → CHOP.

PJP prophylaxis = TMP-SMX (also prevents Toxo, Nocardia, Listeria).

PRES = tacrolimus/cyclosporine + HTN + seizure + posterior MRI changes.

Hepatic artery thrombosis = early catastrophic liver graft loss (Doppler US).

Cardiac allograft vasculopathy = silent (denervated heart), surveillance with angio + IVUS.

Bronchiolitis obliterans syndrome (BOS) = chronic lung rejection, ↓FEV1.

Live vaccines = absolutely contraindicated post-transplant; Shingrix is non-live and indicated.

CYP3A4 inhibitors (↑ tacrolimus): azoles, macrolides (not azithromycin), diltiazem, verapamil, protease inhibitors, grapefruit.

CYP3A4 inducers (↓ tacrolimus): rifampin, phenytoin, carbamazepine, phenobarbital, St. John's wort.

TMP-SMX falsely raises creatinine ~10–20% (blocks tubular secretion).

FSGS recurrence = within hours, massive proteinuria, treat plasmapheresis.

Skin cancer = #1 malignancy post-SOT; sunscreen + annual derm exam.

CV disease = #1 cause of death with functioning graft.

Non-adherence = #1 modifiable cause of late graft loss.

Board Question Stem Patterns

Step 3 management: Notice the pattern — every stem hinges on time since transplant, drug interactions, or distinguishing rejection vs infection vs toxicity.

Board pearl: When two answers seem close, choose the option that (1) confirms with a level/PCR/biopsy and (2) coordinates with the transplant team before empiric escalation.

Stem 1 — Drug interaction: "55F kidney transplant 18 months ago on tacrolimus, MMF, prednisone, presents with tremor, HA, BP 165/95, Cr 2.4 (baseline 1.2). Started clarithromycin 5 days ago for sinusitis." → Tacrolimus toxicity from CYP3A4 inhibition. Next step: check tacrolimus level, hold/reduce dose, switch antibiotic.

Stem 2 — Time-based infection: "42M kidney transplant 3 months ago, fever, leukopenia, mild transaminitis, watery diarrhea." → CMV disease (1–6 month window, D+/R− common). Next: CMV PCR; if tissue-invasive suspected → endoscopy with biopsy; treat IV ganciclovir.

Stem 3 — BK nephropathy: "Kidney transplant 9 months ago, asymptomatic rising Cr from 1.1 to 1.7, UA bland, plasma BK PCR 250,000." → Reduce immunosuppression (decrease MMF first), serial BK PCR. Not antivirals first-line.

Stem 4 — Pregnancy and MMF: "Kidney transplant 3 years ago on tacrolimus, MMF, prednisone wishes to conceive." → Switch MMF to azathioprine ≥6 weeks before conception.

Stem 5 — PTLD: "Lung transplant 2 years ago, EBV-naïve at transplant, presents with fever, weight loss, cervical lymphadenopathy, EBV PCR 800,000." → Biopsy lymph node (EBER+), reduce immunosuppression first, then rituximab.

Stem 6 — PRES: "Liver transplant on tacrolimus, BP 200/120, seizure, MRI shows bilateral parieto-occipital T2 hyperintensities." → PRES: reduce/hold tacrolimus, treat HTN.

Stem 7 — Vaccine: "Kidney transplant recipient wants shingles vaccine." → Recombinant zoster (Shingrix), not live Zostavax.

Stem 8 — Heart transplant CAV: "Heart transplant 5 years ago, exertional dyspnea, no chest pain, abnormal stress." → CAV; coronary angiography + IVUS.

Stem 9 — Skin lesion: "Kidney transplant 10 years ago, enlarging scaly nodule on dorsum of hand." → Cutaneous SCC; biopsy, excise, derm follow-up.

Stem 10 — AMR: "Kidney transplant 1 month ago, sensitized recipient, ↑Cr, biopsy with peritubular capillaritis and C4d+, DSA+." → AMR: plasmapheresis + IVIG ± rituximab.

One-Line Recap

Successful long-term management of solid organ transplant recipients depends on tightly calibrating immunosuppression to avoid both rejection and the predictable cascade of infectious, malignant, metabolic, and cardiovascular complications — anchored by time-since-transplant thinking, drug-interaction vigilance, and aggressive secondary prevention.

Board pearl: When you don't know what to do for a transplant patient on Step 3 — send a CMV PCR, a tacrolimus trough, a UA, a graft ultrasound, and consult the transplant team before any irreversible intervention. That sequence is almost always the right next answer.

Step 3 management: Master three reflexes — (1) anchor on time since transplant, (2) reconcile every medication for CYP3A4 interactions, (3) never give a live vaccine — and most transplant Step 3 questions become pattern recognition rather than memorization.

Rejection vs infection vs toxicity is the central decision in every unwell SOT patient — biopsy and PCR/troughs before pulse steroids whenever feasible.

Time framework drives differential: <1 month nosocomial/surgical/early rejection; 1–6 months opportunistic (CMV, PJP, BK, PTLD, Aspergillus); >6 months community + chronic rejection + malignancy.

Drug-interaction discipline with CYP3A4 (azoles, macrolides, diltiazem ↑ tacrolimus; rifampin, phenytoin ↓) prevents the single most common preventable harm; tacrolimus toxicity = tremor + HTN + AKI + hyperK.

Long-term prevention wins lives: sun protection + dermatology surveillance for SCC, cardiovascular risk reduction (BP <130/80, statin, smoking cessation), PTDM screening, age-appropriate cancer screening, bone health, only inactivated vaccines (Shingrix yes, Zostavax never), adherence reinforcement, and structured transitions of care between transplant center and primary care.