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Cystine Stone

Recurrent kidney stone associated with the genetic disease cystinuria.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Üroloji department. Book Appointment →

What is Cystine Stone?

Cystine stones are kidney stones developing as a result of impaired reabsorption of cystine and dibasic amino acids (ornithine, lysine, arginine - COLA) in the renal tubules due to autosomal recessive genetic cystinuria; they account for 1-2% of all stones, but in pediatric stones this rate rises to 6-8%. Two main genes are responsible: SLC3A1 (type A) and SLC7A9 (type B).

Daily urine cystine excretion in homozygous patients is >250 mg/day (normal <30 mg/day) and exceeds the solubility threshold (250 mg/L) leading to crystal formation. Cystine solubility increases with alkaline urine pH (>7.5); the goal of treatment is alkalization. Stones first appear in the second decade of life, recurrence is rapid (50% within 5 years), staghorn calculi may develop.

Diagnosis includes 24-hour urine cystine measurement, sodium nitroprusside test (qualitative), genetic testing (SLC3A1/SLC7A9), and stone analysis. CT shows stones are slightly radiopaque (low-density compared to calcium stones). Treatment includes hydration (>3 L/day urine), alkalization (potassium citrate), thiol drugs (tiopronin, D-penicillamine), and surgery (ESWL low success - hard stones; PCNL or ureteroscopy preferred).

Symptoms

Recurrent renal colic, flank pain
Hematuria (often microscopic)
Stone disease history starting in childhood/adolescence
Frequent urinary tract infections
Urinary urgency, dysuria
Nausea, vomiting (during attacks)
Family history of stone disease
Hexagonal cystine crystals in urine
Decline in renal function (chronic stage)

Risk Factors

Family history (autosomal recessive inheritance)
Cystinuria gene mutations (SLC3A1, SLC7A9)
Childhood-onset stone disease
Acidic urine pH (<6.5)
Insufficient water intake
High salt diet (increases cystine excretion)
High animal protein consumption
Methionine-rich foods
Dehydration

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Stone disease starting in childhood
  • Recurrent stone attacks (>2 episodes/year)
  • Family history of stone disease + first attack
  • Severe flank pain, hematuria
  • Suspicion of stone in CT but with low density
  • Recurrent UTI accompanying stones
  • Decline in renal function findings

Treatment Methods

01
Hydration (urine output >3 L/day, including night-time fluid intake)
02
Urine alkalization: potassium citrate 60-90 mEq/day (target pH >7.5)
03
Sodium bicarbonate (alternative)
04
Low salt diet (<2 g/day Na)
05
Low animal protein (<0.8 g/kg/day)
06
Methionine restriction
07
Tiopronin (Thiola) 800-1200 mg/day - first-line thiol drug
08
D-penicillamine - second-line (more side effects)
09
Captopril - mild effect
10
Surgery: PCNL (preferred for large stones), ureteroscopy
11
ESWL low success rate (hard stones)
12
24-hour urine cystine and pH follow-up every 6 months
13
Genetic counseling

Which Department to Visit?

You can visit our Üroloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.