RESUMO
Glomerular diseases are one of the most frequent causes of chronic kidney disease, focal and segmental glomerulosclerosis being one of the commonest glomerulopathies. However, the etiology of this glomerular entity, which merely depicts a morphologic pattern of disease, is often not established and, in most of the patients, remains unknown. Nephrologists tend to assume focal and segmental glomerulosclerosis as a definitive diagnosis. However, despite the increasing knowledge developed in the field, genetic causes of glomerular diseases are currently identified in fewer than 10% of chronic kidney disease subjects. Moreover, unexplained familial clustering among dialysis patients suggests that genetic causes may be underrecognized. Secondary focal and segmental glomerulosclerosis due to genetic mutations mainly located in the podocyte and slit diaphragm can occur from childbirth to adulthood with different clinical presentations, ranging from mild proteinuria and normal renal function to nephrotic syndrome and renal failure. However, this histopathological pattern can also be due to primary defects outside the glomerulus. The present report illustrates an adult case of secondary focal and segmental glomerulosclerosis with a dominant tubulointerstitial damage that led to the pursue of its cause at the tubular level. In this patient with an undiagnosed family history of adult kidney disease, a genetic study unraveled a mutation in the mucin-1 gene and a final diagnosis of adult dominant tubular kidney disease-MUC1 was made.
RESUMO
IgA nephropathy is the most frequent cause of primary glomerulonephritis, portends erratic patterns of clinical presentation, and lacks specific treatment. In general, it slowly progresses to end-stage renal disease. The clinical course and the response to therapy are usually assessed with proteinuria and serum creatinine. Validated biomarkers have not been identified yet. In this report, we present a case of acute renal injury with proteinuria and microscopic hematuria in a young male. A kidney biopsy disclosed IgA nephropathy. Podocyturia was significantly elevated compared to normal subjects. Proteinuria, renal function, and podocyturia improved promptly after steroids and these variables remained normal after one year of follow-up, when steroids had already been discontinued and patient continued on valsartan and amiloride. Our report demonstrates that podocyturia is critically elevated during an acute episode of IgA nephropathy, and its occurrence may explain the grim long-term prognosis of this entity. Whether podocyturia could be employed in IgA nephropathy as a trustable biomarker for treatment assessment or even for early diagnosis of IgA nephropathy relapses should be further investigated.