Cystine Stones
Cystine stones are uncommon (~1% of stones) but punish you if treated like ordinary stones — a genetic, lifelong, recurrent disease that begins in childhood and resists shockwave fragmentation.
The big picture
Cystine stones are uncommon (~1% of stones) but they punish you if you treat them like ordinary stones — they are a genetic, lifelong, recurrent disease that begins in childhood, resists shockwave fragmentation, and needs aggressive medical management to control. The key is to recognise the diagnosis early (a young, recurrent stone former; the tell-tale hexagonal crystals) and commit to lifelong prevention, because these patients will form stone after stone if left alone.
The framework: cystinuria is an autosomal recessive defect of tubular cystine reabsorption; stones are recurrent, begin young, form hexagonal crystals, are relatively hard and somewhat radiolucent, and management is lifelong (fluids, alkalinisation, thiol drugs).
Mechanism pathway
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Diagnostic algorithm
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Board traps
Cystinuria is autosomal recessive — a defect of tubular reabsorption of cystine (and the COLA amino acids).
Any cystine in urine is abnormal; hexagonal crystals are pathognomonic.
Recurrent, begins young (childhood/adolescence), lifelong — manage accordingly.
Hard and SWL-resistant — favour ureteroscopy/PCNL, not shockwave.
Stepwise prevention: fluids → alkalinisation → sodium restriction → thiol drugs (tiopronin/penicillamine).
Relatively radiolucent — can be mistaken for uric acid on plain film (but cystine is hard; uric acid dissolves with alkali).