ACALCULOUS CYSTINURIA

We compared quantitative urinary cystine values in stone-forming famil y members and unaffected relatives based on an index stone-forming pat ient, A family pedigree of 39 members was identified, Quantitative uri nalyses and serum biochemical profiles were collected with the subject s on similar diets over 72 hours. Detailed medical histories were obta ined, Three family members are stone-forming cystinuric patients with a mean urinary cystine excretion of 496 mg/g of creatinine per day. Si x persons without a history of stones (mean age 50) had a mean urinary cystine excretion of 364 mg/g of creatinine per day. Thirty-four fami ly members had elevated urinary cystine concentrations (mean 151 mg/g of creatinine per day), and only two family members had normal urinary cystine excretion, Fifteen subjects with elevated urinary cystine val ues (>150 mg/g of creatinine per day) had no history of urinary stones despite a mean age of 44 years, Urinary electrolytes and volumes were similar in the stone-forming and non-stone-forming groups. Thirty-nin e per cent of the persons from this family pedigree had elevated quant itative urinary cystine concentrations and no history of urinary stone s despite a mean age of 44 years. Acalculous cystinuria is an elevated urinary cystine concentration without evidence of urinary stone disea se, Despite abnormal urinary cystine excretion, acalculous cystinuria does not necessarily culminate in clinical urinary stone disease.