A 58-year-old female presents to the Emergency Department with a several-day history of progressive, debilitating fatigue and generalized malaise. She reports new-onset dark, tea-colored urine (cola-colored) and a significant reduction in her urine output. She also notes new headaches and visual disturbances, which she attributes to feeling unwell. Her home medications include:
- Tacrolimus (trough level 10 ng/mL)
- Mycophenolate Mofetil
- Prednisone
Vital Signs at Presentation:
- Blood Pressure: 160/95 mmHg (new-onset hypertension, significantly elevated from baseline)
- Heart Rate: 105 bpm (sinus tachycardia)
- Respiratory Rate: 18 breaths/min
- Oxygen Saturation: 98% on room air
Physical Examination Findings:
- General: Ill-appearing, pale, and fatigued.
- Cardiovascular: Tachycardic, no jugular venous distention.
- Pulmonary: Clear lung fields on auscultation, no wheezing or crackles.
- Abdominal: Soft, non-tender, no hepatosplenomegaly.
- Neurological: Alert and oriented; no focal neurological deficits noted.
- Skin: Pallor noted; no visible petechiae or ecchymoses.
Key Laboratory Findings:
|
Test
|
Result
|
Reference / Baseline
|
|
Hemoglobin (Hb)
|
8.7 g/dL
|
(Down from 12 g/dL 2 weeks prior)
|
|
Platelets
|
85,000/µL
|
(Thrombocytopenia)
|
|
Lactate Dehydrogenase (LDH)
|
580 U/L
|
(Markedly elevated)
|
|
Haptoglobin
|
< 30 mg/dL
|
(Undetectable)
|
|
Peripheral Smear
|
2+ schistocytes
|
(Evidence of microangiopathic hemolysis)
|
|
Serum Creatinine
|
3.2 mg/dL
|
(Baseline: 1.1 mg/dL)
|
|
Urinalysis
|
|
|
|
Appearance
|
Dark/Amber
|
|
|
Blood
|
3+
|
|
|
Protein
|
2+
|
|
|
Microscopy
|
20-30 RBCs/HPF (microscopic hematuria)
|
No casts seen
|
|
C4d Staining (recent biopsy)
|
Negative
|
|
|
Donor-Specific Antibodies (DSA)
|
None Detected
|
|
What is the MOST likely diagnosis?
