Cystinuria is a hereditary metabolic disorder in which patients have abnormally high levels of the amino acid cystine in their urine, which can lead to the formation of stones in the bladder, ureter, and kidney. Cystinuria is one of the causes of persistent kidney stones, which if left untreated can cause serious damage to the kidneys and surrounding organs. 

Cystinuria is normally asymptomatic as long as stones have not formed. However, if a kidney stone is present, patients may experience nausea or vomiting, chronic pain in the side and back below the ribs, pain urinating, discolored urine, and a persistent need to urinate. Cystinurics are at a higher risk of chronic kidney disease. 

Treatment of cystinuria may involve dietary changes, nutritional supplements, and drinking plenty of water. Medication such as penicillamine binds with the cystine in the urine and may be prescribed to prevent the formation of more kidney stones.