Dimercaptosuccinic acid distribution in renal tubular acidosis.

A 99Tcm dimercaptosuccinic acid (DMSA) scan performed after a urinary tract infection demonstrated an unusual pattern of isotope uptake, promoting further investigations leading to a diagnosis of renal tubular acidosis secondary to nephropathic cystinosis. This is known to affect isotope imaging but a unique feature in this undiagnosed case was the uncorrected metabolic acidosis, which had further altered the distribution of the DMSA. It is noteworthy because other patients referred for imaging with renal disease may also have abnormalities of acid base balance.