[Cystine as a risk factor of the stone formation in kidney: the reference value range of urinary excretion, the stage diagnosis of cystine metabolism disorder].

for the objective assessment of the cystine metabolism status the evaluation of the degree of cystinuria is necessary in order to form the risk group for cystine nephrolithiasis. The reference value ranges of cystine urinary excretion developed in the age aspect and "cystine / creatinine index" in morning urine samples will provide the opportunity to identify the state of the cystine exchange from early childhood and develop differentiated program for the prevention of stone formation in the kidneys.