Tsüstiinuria

Tsüstiinuria is a rare inherited disorder that affects the kidneys' ability to reabsorb certain amino acids from the urine. Specifically, it impairs the reabsorption of cystine and certain other dibasic amino acids, leading to their increased excretion in the urine. This condition is caused by mutations in genes responsible for amino acid transporters in the kidney tubules.

The primary clinical manifestation of tsüstiinuria is the formation of cystine stones in the kidneys and urinary tract. Due to the low solubility of cystine, these stones can lead to recurrent kidney infections, flank pain, blood in the urine (hematuria), and potentially kidney damage if left untreated. The severity of stone formation can vary significantly among individuals, even within the same family.

Diagnosis is typically made by measuring the amino acid levels in urine and by identifying cystine crystals. Genetic testing can confirm the diagnosis and identify the specific gene mutation.

Treatment focuses on preventing stone formation and managing symptoms. This includes increasing fluid intake to dilute urine, alkalinizing the urine to increase cystine solubility, and in some cases, using medications that can bind to cystine to make it more soluble. Surgical intervention may be necessary to remove large or problematic stones. Without proper management, tsüstiinuria can lead to chronic kidney disease and renal failure.