ystinuria with the overall prevalance of 1 person per 7.000 population is an autosomal-recessive defect in reabsorptive transport of cystine and dibasic amino acids ornithine, arginine, and lysine from the luminal fluid of the renal proximal tubule. Two genes SLC3A1 (located on chromosome 2p16.3-p21) and SLC7A9 (located on chromosome 19q12-13.1) are responsible for cysteine reabsorbtion. Mutations of these genes lead to inability of renal tubules to reabsorb cystine and phenotypic manifestation of cystinuria. The relative insolubility of cystine at physiological urine pH lead to stone formation, infection, obstruction and ultimately chronic kidney disease. 1,2 The other dibasic amino acids including ornithine, arginine and lysine are soluble, so increase in their urinary excretion does not lead to stones. Cystine stones which occur most commonly within the first two decades of life are found in 6-8% of pediatric renal lithiasis cases while 1-2% of adult stone formers. 2 The median age of onset of stones was reported as 12 years. 3 The appropriate management of cystinuria is often challenging and requires close follow-up of the patient. Here, recurrent cystine stone former 47 years old man with no sign of urolithiasis until 35 years of his life was presented. Unusual Cause of Nephrolithiasis: Cystinuria A AB BS S T TR RA AC CT T Cystinuria is a rare hereditary disease in which excretion of detectable amount of cysteine, lysine, ornithine and arginine amino acids in the urine is present leading to cysteine nephrolithiasis. Over 100 mutations for SLC3A1 and SLC7A9 genes were identified for this disease. 47 years old male patient suffering from recurrent nephrolithiasis analysis of which revealed L-cysteine type stone for the last 12 years applied to our hospital with the complaint of flank pain. Obesity, hyperglycemia, hypertriglyceridemia, microscopic hematuria, macroalbuminuria, multiple stones in the urinary tract with the diameter of 1 cm and hypercystinuria were detected. Urology consultation for stone removal, alkalization and increasing the volume of urine, life style modifications in order to lose body fat, potassium citrate and tiopronine were adviced to the patient. If stones passed through urinary tract are not analysed, diagnosis of cystinuria will be missed out. With this case, an unlucky but common state for patients with cystinuria is discussed.

nder normal conditions, kidneys assist glucose homeostasis by synthesizing glucose via gluconeogenesis and preventing urinary glucose loss via tubulary glucose reabsorption. 1 Reabsorption of glucose which is freely filtered in the glomeruli almost completely occur in proximal tubules only. This glucose reabsorption is mostly (90%) carried out by sodium-glucose cotransporters type 2 (SGLT-2) and glucose transporters 2 (GLUT2). So in patients with normal kidney function, significant glycosuria does not generally occur until the plasma glucose concentration exceeds 180 mg/dL (10 mmol/L). 2 Glycosuria may be due to either the inability of the kidney to reabsorb filtered glucose in the proximal tubule despite normal plasma glucose concentration, or to an overflow scenario related to high plasma glucose concentrations overwhelming the capacity of the renal tubules to reabsorb glucose. The commonest cause of glycosuria is uncontrolled diabetes mellitus. Abnormally elevated levels of glucose in the blood result in high amount of filtered glucose waiting to be reabsorbed through overactive SGLT2 which execute reabsorption eventually. When glycosuria occurs with a normal plasma glucose, a primary defect of proximal tubule reabsorption (renal glycosuria) needs to be considered. 1,2 Renal glycosuria is a rare and long