CaCr Clearance Ratio Calculator

The calcium:creatinine (CaCr) clearance ratio is used to differentiate causes of hypercalcaemia.

Parameter	Value	Units
Serum Calcium		mmol/L µmol/L
Serum Creatinine		mmol/L µmol/L
Urine Calcium		mmol/L µmol/L
Urine Creatinine		mmol/L µmol/L
CaCr Clearance Ratio: [result here]

Type into the above fields and the result will appear instantaneously.

Interpretation

A CaCr clearance ratio > 0.01 essentially excludes Familial Hypocalciuric Hypercalcaemia (FHH).

Notes

In the setting of hypercalcaemia, a low CaCr clearance ratio is consistent with:

• Altered function of the calcium sensing receptor (CaSR) i.e. Familial Hypocalciuric Hypercalcaemia (FHH)
• Very low calcium intake
• Mild renal insufficiency
• Thiazide diuretic use
• Lithium use

In the setting of hypercalcaemia, a normal or elevated CaCr clearance ratio is consistent with:

• Primary hyperparathyroidism
• Loop diuretic use

Formula

(Urine Calcium × Serum Creatinine) ÷ (Serum Calcium × Urine Creatinine)

Use the same units for all measurements.

The ClinicFire calculator will correct them for you.