Synopsis
Use reliable stone composition, serum results and appropriately collected urine to identify a recurrence mechanism, recognise high-risk disease and make a result-driven specialist or prevention decision.
- NICE recommends serum calcium measurement in adults with renal or ureteric stones and consideration of stone analysis. EAU recommends reliable stone analysis and basic metabolic evaluation for all stone formers, with specific metabolic testing for high-risk patients.
- Use infrared spectroscopy or X-ray diffraction for recovered stone material. Radiopacity, CT density and urine pH provide clues but do not establish a definitive composition on their own.
- EAU specific metabolic evaluation uses two consecutive 24-hour urine collections when stable, infection-free and on the usual diet and fluid intake: no earlier than twenty days after the acute episode and preferably around three months.
Investigation priorities
Identify the mineral composition that guides risk and treatment.
Management branches
A forty four year old woman has a second calcium-phosphate-containing stone and no current infection.
- Stone analysis by infrared spectroscopy shows mixed calcium phosphate and calcium oxalate. Her albumin-adjusted serum calcium is 2.78 mmol/L. The clinician arranges repeat calcium with PTH and reviews supplements, renal function and symptoms before calling the problem idiopathic hypercalciuria or starting a calcium-lowering urinary drug.
- Repeat calcium is 2.76 mmol/L and PTH is 9.1 pmol/L against the supplied laboratory range 1.6–6.9. Kidney function is preserved. Two properly collected stable-state urine samples also show high calcium excretion. The concordant results support PTH-dependent hypercalcaemia, and endocrine assessment confirms primary hyperparathyroidism after evaluating relevant alternatives.