Introduction Cystinuria is a rare cause of renal lithiasis, contributing to 7% of the cases of nephro/urolithiasis in childhood. An inherited autossomal recessive defect of the renal tubular and small intestine reabsorptive transport of cystine and dibasic amino acids leads to elevated excretion of cystine in the urine.
Methods Retrospective study of patients in pediatric nephrology department with the diagnosis of nephro/urolitiasis and urinary increased excretion of cystine. The diagnosis of Cystinuria is made by urinary quantification of cystine. Cystinuria was detected when the cystine concentration is superior to 300 mg/L.
Results We report three cases. The first one is a 5-months-old infant with gross hematuria. The renal ultrasound revealed renal bilateral lithiasis. The second case was a 15-years-old girl with urinary infection. The renal ultrasound detected bilateral stones. The last case is a 14-years-old boy, originating from Angola, with a personal history of repeated urinary infections and admitted with a severe renal chronic insufficiency. The work-up of renal disease confirmed the presence of renal bilateral lithiasis.
The medical therapy consists of increased oral fluids intake, urine alkalinization, low-salt diet, reduced rich foods in cystine and eventually the use of medication.
Conclusions This is a disease with variable expression, which may be clinically obvious from the neonatal period or remain silent, being revealed later under the form of renal chronic insufficiency. It should be considered during the work-up for causes of nephro/urolitiasis.