SERUM CALCIUM MEASUREMENT : TOTAL VERSUS FREE (IONIZED) CALCIUM

Measurement of serum free (ionized) calcium (Ca++) reflects true calcium status of the body in health and disease. Present study evaluates efficacy of Ca++ over total calcium (CaT) in serum for calcium status. 52 subjects were enrolled for study. Anaerobic fasting blood sample for Ca++ measurement and autoclaved plain bulb for estimation of CaT, Total protein (TP) and Albumin was used. CaT, Corrected CaT, Ca++, Calculated Ca++ were measured and correlated. Corrected CaT and calculated Ca++ were derived from the measured parameters. Study group showed significant difference between CaT and corrected CaT (p<0.006), Ca++ and calculated Ca++ (p<0.001). Negligible correlation was observed between Ca++ and serum protein. Positive correlation was observed between CaT and calculated Ca++, TP and albumin. Findings indicate that Ca++ levels are independent of serum protein status. With scrupulous sampling, Ca++ may be a better parameter than presently used CaT for assessing calcium status in serum.