Stone Evaluation
HISTORY AND PHYSICAL KEY PARTS
LABORATORY
For 1st time stone formers:
Don't screen for VitD unless suspect VitD toxicity. If testing, test 25-OH-VitD b/c not as highly regulated and longer half life (2-3 weeks)
- Hypercalciuria
- Diet : Salt, calcium, animal protein, VitD exposure
- Screen for PTH: GI, psychiatric, bone pain
- Meds: lithium, corticosteroids, loop diuretic exposure
LABORATORY
For 1st time stone formers:
- Serum Ca++, Cr, uric acid, electrolytes
- If hypercalceima: repeat with albumin, globulin, electrolytes, BUN, Cr and PO4
- If persistent elevation, perform ionized Ca++
- Only screen for PTH if suspected and with elevated or high normal serum Ca++
Don't screen for VitD unless suspect VitD toxicity. If testing, test 25-OH-VitD b/c not as highly regulated and longer half life (2-3 weeks)
- Hypercalciuria
- Defined as 24-hr >250mg/day in women or 300mg/day in men or 4mg/kg/day in either sex (1)
- Also defined as 24 hour urine calcium exceeding 200mg/day on a diet restricted in calcium, sodium and animal protein (2)
- If unable to collect 24 hr urine, a spot urine calcium-to-creatinine ration can be used, but this is inferior.
- Should be repeated in 6 months after initiating therapy to evaluate for changes
