Fever and Rising Creatinine at Post-Op Day 9
A 48-year-old woman is 9 days out from a deceased-donor kidney transplant (CMV D+/R-, EBV D+/R-). Induction was basiliximab; maintenance is tacrolimus, mycophenolate, and prednisone. Today: temp 38.6 C, BP 132/84, urine output down from 1.2 L/day to 400 mL/day, creatinine up from 1.4 to 2.3 mg/dL. Tacrolimus trough is 14 ng/mL (target 8-10). She reports 2 days of burning on urination and lower abdominal discomfort. WBC 11.8, platelets 140 (baseline 210). Ultrasound shows mild pelvicalyceal dilation without a discrete collection; bladder is not distended. Blood and urine cultures are pending.
1. Build a prioritized differential and state what you would do in the next 6 hours.
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Differential, ranked by urgency:
- Urinary tract infection/pyelonephritis - dysuria, fever, mild hydronephrosis; common early and can ascend.
- BK virus nephropathy - usually later, but rising creatinine with high tacrolimus warrants attention; not the acute driver today.
- Acute rejection - possible; fever and graft dysfunction fit, but infection must be excluded first.
- Drug toxicity - tacrolimus 14 exceeds target; calcineurin-inhibitor toxicity contributes to creatinine rise.
- Surgical/urologic complication - mild dilation without collection; ureteral obstruction or leak still possible.
Next 6 hours:
- Blood and urine cultures before antibiotics, then start empiric coverage for gram-negatives per local antibiogram (adjust renally).
- Hold one mycophenolate dose pending cultures given leukopenia trend and infection concern; do not stop tacrolimus abruptly.
- Reduce tacrolimus toward target; recheck trough.
- Strict intake/output, daily weights, repeat creatinine in 12-24 hours.
- If fever persists >48-72 h or creatinine climbs despite treatment, proceed to Doppler ultrasound and consider graft biopsy with BK PCR.
Trap to avoid: Reflexively treating the creatinine rise as rejection and bolting steroids - that would worsen an infection.
2. The patient asks whether the high tacrolimus level 'means the kidney is failing.' How do you explain the interaction among infection, drug level, and graft function?
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Explain three coupled processes in plain language:
- The infection is the immediate problem. A urinary infection raises fever and can inflame the graft, pushing creatinine up.
- Her anti-rejection medicine is running high. Tacrolimus at 14 is above her target; too much can itself stress the kidney, and it is being adjusted downward.
- We separate the causes before acting. Lowering immunosuppression helps fight infection but raises rejection risk - so we act in steps and watch labs.
Emphasize: a creatinine bump at day 9 is common and often reversible; the plan is sequential (cultures, antibiotics, level adjustment, then biopsy if not improving). Avoid promising a single cause. Invite questions and note that her CMV/EBV mismatch status will need monitoring later.