ANCA-Negative Pauci-Immune Maintenance Duration — ESENeph MCQ

Correct answer: A — Add tiopronin for persistent cystinuria with toxicity monitoring

The best answer is “Add tiopronin for persistent cystinuria with toxicity monitoring”. After very high fluid intake and urine alkalinisation, thiol drugs form more soluble mixed disulfides; adverse effects and urine cystine response require specialist monitoring. “Add a thiazide when concurrent hypercalciuria remains clinically important” is less appropriate because thiazides target hypercalciuric calcium stones “Add allopurinol when concurrent hyperuricosuria remains clinically important” is less appropriate because cystine is a dibasic amino acid, not a purine metabolite “Continue alkalinisation while checking urine pH and cystine excretion” is less appropriate because cystine solubility improves as urine pH rises “Use dietary sodium and protein reduction alongside high fluid intake” is less appropriate because this is not standard cystinuria treatment

Reference: EAU guideline on urolithiasis: https://uroweb.org/guidelines/urolithiasis/chapter/guidelines