A 32-year-old black man was referred to a nephrology clinic for proteinuria. He reported foamy urine for a few months. Urinalysis was positive for protein. He denied any family history of kidney diseases. He was not taking medications except for ibuprofen occasionally for headache. He denied use of tobacco or illicit drugs. Physical examination showed a blood pressure of 139/75 mm Hg and weight of 85 kg and a body mass index of 27 kg/m2. There was trace bilateral ankle edema. Otherwise, his examination was unremarkable. Urine sediment was bland with 3 non-dysmorphic RBCs per HPF.
Other relevant laboratory test results are listed below:
- 24-hour urine collection: 3.1 g protein, 2850 g albumin
- Serum creatinine: 1.3 mg/dL
- Cystatin C: 1.25 mg/dL
Estimated GFR: 72 mL/min/1.73m2 based on CKD-EPI creatinine equation and 65 mL/min/1.73m2 based on CKD-EPI cystatin C equation
- Serum albumin: 3.6 mg/dL
- Serum electrolytes within normal limits.
All serologies were negative, including anti-nuclear antibody (ANA), anti-double stranded DNA antibody (anti-dsDNA), and anti-neutrophil cytoplasmic antibody negative (ANCA). Complement C3 and C4 levels were within normal range.
Screening for HIV, syphilis, hepatitis B and C were negative.
A renal biopsy was performed (Figure 1). It showed focal and segmental glomerulosclerosis (FSGS) with mild tubular atrophy and interstitial fibrosis. Electron microscopy of the biopsy sample revealed diffuse podocyte foot process effacement.
The patient was counseled with regard to lifestyle modification, including exercise and diet to lose weight. He was also started on lisinopril for blood pressure control. Proteinuria, however, did not improve despite being on lisinopril 40 mg daily for 8 weeks. He was then started on prednisone at 1 mg/kg/day. Within 8 weeks, he achieved complete remission, with reduction of proteinuria to less than 0.3 g/day. Prednisone was then slowly tapered to 5 mg/day over the following 6 months. At a follow-up visit, he had been taking prednisone 5 mg/day for 2 months. Repeat 24-hour urine collection showed total protein of 2.5 g/day and albumin of 1930 mg/day.
This case was prepared by Yongen Chang, MD, PhD, Assistant Clinical Professor, Division of Nephrology and Hypertension, University of California Irvine (UCI) and Jonathan Zuckerman, MD, PhD, Assistant Clinical Professor, Serive Chief, Renal Pathology, Department of Pathology and Laboratory Medicine, University of California Los Angeles.