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Urolithiasis
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Thomas Johnston, James Armitage, Oliver Wiseman
The following are true of cystinuria, except:Cystinuria is inherited as an autosomal dominant condition with an incidence of 1 in 20,000.The pKa of cystine is 8.3 and the cyanide nitroprusside test is used to test for cystinuria.Treatment with effervescent ascorbic acid (vitamin C) may increase the solubility of cystine.Homozygous cystinurics typically pass more than 600-mg cystine in their urine per day.Cystine stones are usually visible on plain abdominal radiograph due to the presence of disulphide bonds.
The urinary tract and male reproductive system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Luis Beltran, Daniel M. Berney
The main types of urinary calculi are as follows: Calcium-containing stones, the calcium salt being predominantly oxalate with lesser amounts of calcium phosphate. These comprise more than 75% of all urinary calculi and are characteristically laid down in an acid urine.Complex triple phosphate stones including magnesium, ammonium, carbonate, and calcium components. These comprise 15% of urinary calculi and are laid down in alkaline urine. They may form an outer laminated deposit on other stones and are strongly associated with urinary tract infection.Uric acid and urate–uric acid stones comprise 5% of urinary calculi but affect up to 20% of patients with gout. Similar to calcium-containing stones they are typically laid down in an acid urine. Pure uric acid stones are radiolucent, rendering their detection on a plain abdominal radiograph virtually impossible.Cystine stones occur in primary cystinuria, a rare but important renal disease in childhood.
Renal and urinary tract diseases
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Progressive renal failure is one of the main features of cystinosis, which is an autosomal recessive disorder. The specific gene CTNS encodes a lysosomal membrane protein, cystinosin. The condition must not be confused with the renal transport defect cystinuria (see later).
What are the main challenges to the pharmacological management of cystinuria?
Published in Expert Opinion on Pharmacotherapy, 2020
Michael E. Rezaee, Andrew D. Rule, Vernon M. Pais
It is important to recognize inherent challenges in cystinuria management due to low medication compliance. Prior research has shown that less than 20% of cystinuria patients achieve and maintain urinary cystine levels low enough to prevent stone formation [16]. Other chronic conditions, such as hypertension, have higher documented medication compliance rates ranging from 35–60% [17]. Cystinuria is a genetic, chronic disease with an early average age of onset between 20 and 30 years of age. Thus, it can be difficult for patients to comply with long-term medication use that requires taking multiple pills 3 to 4 times a day, especially given occasionally intolerable side effects of many of the medications. However, these patients are also often highly motivated due to frequent debilitating episodes of renal colic. As such, cystinuria patients should be managed in comprehensive multidisciplinary metabolic stone clinics, comprised of nephrologists, urologists, and dietitians to achieve the best possible outcomes for these patients [18]. This is an especially important management strategy given that 25% of cystinuria patients are known to develop non-cystine stones during their lifetime [19].
Alpha lipoic acid as a novel therapeutic approach to cystinuria
Published in Expert Opinion on Orphan Drugs, 2018
Scott V. Wiener, Thomas Chi, Marshall L Stoller
Cystinuria is a rare genetic disorder that results in recurrent, debilitating kidney stone episodes. Cystine is a dimer of two cysteine molecules that is poorly soluble at typical urinary pH (5–7) and rapidly crystalizes. Traditional management strategies rely on extremely high fluid intake (up to 5L daily), dietary management, altering urine pH to increase cystine solubility and competitive binding of cysteine molecules to form more soluble dimers. These treatments are poorly tolerated and require significant lifestyle modification for affected patients. Surgical treatments tend to be more frequent, more invasive, and less effective for affected patients due to the radiographic (poorly visible) and physical characteristics (difficult to break) of cystine stones.
Established and recent developments in the pharmacological management of urolithiasis: an overview of the current treatment armamentarium
Published in Expert Opinion on Pharmacotherapy, 2020
Mohamed Abou Chakra, Athanasios E. Dellis, Athanasios G. Papatsoris, Mohamad Moussa
Captopril can be used for cystinuria, it form captopril-cysteine disulfide complex which is 200 times more soluble than cystine, thus long-term captopril therapy may be useful in the treatment of cystinuria with 150 mg or 75 mg dose per day [123]. Cohen et al reported a decrease in cystinuria in nine adult patients with a history of multiple cystine stones despite standard fluid and alkalization therapy. Those patients received 50 mg of captopril, 3 times daily in addition to the standard therapy [124]. However, high quality data on captopril efficacy on formation and prevention of cystine stone are lacking.