What question did this study set out to answer?

The study aims to highlight the complexity of diagnosing renal tuberculosis presenting as nephrotic syndrome.

March 17, 2026Open Access

Nephrotic Syndrome Secondary to Tuberculosis – A Diagnostic Challenge

Key Points

The study aims to highlight the complexity of diagnosing renal tuberculosis presenting as nephrotic syndrome.
Case report of a male patient with nephrotic syndrome and respiratory symptoms.
Initial work-up included urinary sediment analysis, chest CT, and molecular tests for TB.
Multiple urine samples were collected for TRM-TB testing and culture.
Kidney biopsy was performed to assess renal tissue involvement.
Nephrotic-range proteinuria confirmed (24g/24h).
Chest CT revealed centrilobular micronodular opacities consistent with TB.
Trace detection of TB in urine samples confirmed renal tuberculosis.
Patient improved after initiating standard TB therapy.
Diagnosis required multiple urine samples and careful clinical assessment.

Abstract

Tuberculosis (TB) is a preventable and curable infectious disease caused by Mycobacterium tuberculosis. More than 10 million people continue to develop TB every year, a number that has been rising since 2021. Although TB mainly affects the lungs, extrapulmonary forms occur in 10–20% of cases. Genitourinary TB is the second most common site, present in 2–20% of those with pulmonary TB and in 30–40% of extrapulmonary TB. Pyuria, proteinuria, and renal dysfunction may be early manifestations of granulomatous renal disease. Isolated hematuria is also a possible presentation of renal TB. A 51-year-old male experiencing homelessness, alcohol user, smoker, and illicit drug user, was referred to a tertiary hospital due to generalized edema for two weeks, associated with marked penile and scrotal edema, oliguria with reddish urine, dyspnea, and dry cough. Initial workup for edematous syndrome showed urinary sediment with proteinuria and hematuria. A 24-hour urine collection confirmed nephrotic-range proteinuria (24g/24h). Due to respiratory complaints, chest CT was performed and revealed centrilobular micronodular opacities, sometimes with a tree-in-bud pattern. Sputum smear microscopy was negative, and rapid molecular test for TB (TRM-TB) in sputum showed only trace detection, insufficient for a diagnosis of pulmonary TB in an immunocompetent patient. Further investigation included 5 urine samples for TRM-TB and culture. The first two were negative; the third sample showed trace detection, confirming extrapulmonary TB with renal involvement. Standard therapy with rifampicin, isoniazid, pyrazinamide, and ethambutol was initiated. Due to severe behavior, disorganized speech, and agitation, lumbar puncture was performed to rule out TB of the central nervous system, with normal CSF and negative TRM-TB. Kidney biopsy showed crescentic glomerulonephritis with C3 deposition, without tubulointerstitial involvement. The patient improved regarding edema and renal function after RIPE regimen and was later transferred to a psychiatric unit to continue treatment. Renal TB requires high clinical suspicion, and diagnosis usually requires at least 3–6 urine samples for TRM-TB and culture.

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