Cystine urolithiasis

Cystinuria, also called cystine urolithiasis, arises from impaired reabsorptive transport of cystine... 

Cystinuria is an autosomal recessive disorder of renal mbular teab-sorption of cystine, ornithine, arginine and lysine (mnemonic COAL). Cystine (a dimer of cysteine Chapter 6) is sparingly soluble and accumulates in the tubular fluid, forming bladder and kidney stones (cystine urolithiasis). Cystine is so-called because cystine stones were discovered in the cyst (i.e. bladder). 

Approximately 10% of the human population (with regional differences indicating both genetic and environmental factors [33]) is affected by the formation of stones or calculi in the urinary tract. Urolithiasis is not only a painful condition, but also causes annual costs to the health system in the order of billions of dollars in the USA alone [34, 35]. Based on their composition, structure and location in the urinary tract, renal stones have been classified into 11 groups and their formation mechanisms have been discussed together with alterations in urinary parameters and metabolic risk factors for renal lithiasis [35]. Approximately 70% of these stones contain calcium oxalate monohydrate (COM) and dihydrate as major components, while other calculi are composed of ammonium magnesium phosphate (struvite), calcium phosphates (hydroxyapatite and brushite), uric acid and urates, cystine and xanthine. An accurate knowledge of the solubilities of these substances is necessary to understand the cause of renal or bladder calculi formation and find ways towards its prevention and treatment [36]. 

III [10]. Homozygotes and compound heterozygotes develop urolithiasis due to the low solubility of cystine (<200-300 mg/1). The intestinal malabsorption of cystine and dibasic amino acids has no clinical relevance. Treatment has to prevent stone formation by high fluid intake during day... 

---