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cystinuria

3 types of cystinuria: - Type 1 (fully recessive or silent) - Type 2 (high excretor) - Type 3 (moderate excretor) Pathology: 1) intestinal & renal tubular transport disorder (reduced absorption) of dibasic amino acids: - C cystine - O ornithine - L lysine - A arginine 2) cystine is the least soluble in normally acidic urine & tends to precipitate 3) homozygotes develop urolithiasis Genetics: 1) autosomal recessive 2) mutation in the gene for SLC3A1 (type 1) 2) mutation in the gene for SLC7A10 3) mutation in the gene for SLC7A9 Clinical manifestations: 1) nephrolithiasis (cystine stones) 2) short stature Laboratory: - urinalysis a) cystine crystalluria b) positive nitroprusside test Management: 1) stones can be dissolved with: a) urinary alkalinization b) high take of fluids c) maintain urine pH at 7 2) chelating agents may be useful - D-penicillamine or tiopronin - captopril if hypertension [1] 3) pyridoxine (vitamin B6) 25 mg PO QD 4) potassium citrate as inhibitor of stone formation 5) low protein diet 6) restrict dietary sodium

Interactions

disease interactions

Related

cystine cystine in urine hypotonia-cystinuria syndrome

General

genetic disease of the kidney inborn error of metabolism

Database Correlations

OMIM correlations

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 17. American College of Physicians, Philadelphia 1998, 2015
  2. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1324
  3. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 616