Kidney Stones (Cystine)

Cystine kidney stones are a type of kidney stone caused by the buildup of cystine, an amino acid, in the urinary system. These stones form when cystine crystals accumulate in the kidneys and urinary tract, leading to painful blockages and potential damage. The condition primarily affects the urinary system, including the kidneys, ureters, and bladder. People with this condition often experience recurrent episodes of severe flank pain and difficulty urinating. The stones can cause urinary tract infections and may lead to complications if not managed properly. This condition is caused by a genetic problem that affects how the kidneys handle cystine.

Cystine kidney stones are formed due to a hereditary disorder called cystinuria, characterized by defective renal tubular reabsorption of the amino acid cystine and dibasic amino acids. This defect results from mutations in the SLC3A1 or SLC7A9 genes, leading to increased cystine concentration in the urine. Because cystine is poorly soluble in urine, it precipitates and forms crystals and stones. These stones are typically radio-opaque and can cause recurrent nephrolithiasis with symptoms such as severe flank pain, hematuria, and urinary obstruction. The condition is significant because cystine stones tend to be recurrent and resistant to conventional stone prevention strategies, often requiring specialized management. Early diagnosis is important to prevent chronic kidney damage and recurrent infections.