Poor renal accumulation of Tc-99m-DMSA in idiopathic tubular proteinuria

In Japanese patients idiopathic tubular proteinuria presents mainly as asym ptomatic tubular low molecular weight proteinuria. This disease has recentl y been shown to resemble Dent's disease which is characterized by tubular p roteinuria, hypercalciuria, rickets and eventual renal failure. We report o n 4 children with idiopathic tubular proteinuria. Although they had normal renal function, as evidenced by serum creatinine or creatinine clearance, t hey had very poor renal accumulation of Tc-99m-DMSA and the presence of lar ge amounts of tracer in the bladder. Additionally, the patient with the lar gest amounts of tubular proteinuria had the poorest renal accumulation of t he 4 patients. The renal accumulation of tracer decreased with time from a maximum at 10 min after injection. These findings demonstrate that the trac er, once taken to be confined to the proximal tubular cells, is immediately excreted to the tubular lumen. We suggest that poor renal accumulation of Tc-99m-DMSA is very important in elucidating the mechanism of idiopathic tu bular proteinuria, and that Tc-99m-DMSA renoscintigraphy is useful in the e valuation of the patient's renal function over time.