Hypercalcemia - Calcium Creatinine Clearance Ratio Calculator

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Enter serum and 24h urine values with consistent units (e.g., mg/dL and mg/24h).
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Ca/Cr Clearance Ratio
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Interpretation Notes
  • Familial Hypocalciuric Hypercalcemia (FHH): Characterized by hypercalcemia with inappropriately normal or elevated PTH and a low calcium–creatinine clearance ratio (CCCR).
    • CCCR < 0.01: FHH likely
    • CCCR 0.01–0.02: Indeterminate (FHH possible)
    • CCCR > 0.02: FHH unlikely
    • 24-hour urine calcium < 100 mg/day may further support FHH
  • Exclude Secondary Causes of Hypocalciuria: Vitamin D deficiency, very low calcium or sodium intake, renal insufficiency, thiazide diuretics, or lithium therapy should be considered before diagnosing FHH.
  • Normal or Elevated CCCR in Hypercalcemia: More consistent with primary hyperparathyroidism (PHPT) or loop diuretic use.
  • 24-Hour Urine Collection Quality: Adequate volume is required for interpretation (≈0.5 mL/kg/hr; ~840 mL/day for a 70-kg individual). Hypercalciuria cannot be reliably excluded if urine creatinine concentration > 40 mg/100 mL.
  • Hypercalciuria thresholds (strong surgical indication per PHPT guidelines):
    • ≥250 mg/day (women)
    • ≥300 mg/day (men)
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