Abstract
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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alan, H. Gowenlock, Janet, R. McMurray and Donald, M McLanchlan (2002) Varley’s Practical Clinical Biochemistry, 6th Ed., pg 601.
Robertson, W.G. and Marshall, R.W. (1979) Calcium measurement in serum and plasma: Total and Ionized. Crit. Rev. Clin. Lab. Scan. vol. 11, 271–304.
McLean, F.C. and Hastings, A.B. (1934) A biological method for the estimation of calcium ion concentration. J. Biol. Chem. vol. 107, 337–350.
McLean, F.C. and Hastings A.B. (1935) The state of calcium in the fluids of the body. The conditions affecting the ionization of calcium. J. Biol. Chem. vol. 108, 285–322.
McLean, F.C. and Hastings, A.B. (1935) Clinical estimation and significance of Ca++ ion concentration in the blood. Am. J. Med. Sci. vol. 189, 601–613.
George, N.B. Jr., Catherine, Brassard and Salvador, F. Sena (1986) Measurement of ionized calcium in serum with ion selective electrodes: A mature technology that can meet the daily service needs. Clin. Chem. vol. 3218, 1437–1447.
Kragh, Hansen V. and Vorum, H (1993) Quantitative analysis of the interaction between calcium ions and human serum albumin, Clin. Chem. vol. 39, 202–208.
Carl, A. Burtis and Edward, R. Ashwood (1990) Tietz, Clinical guide to laboratory tests, 2nd Ed, (Philadelphia: W.B. Saunders, 60), 98–99, 118–119, 456–459, 510–511, 720–721.
Bishop, M.L., Duben-Engelkirk, J.L. and Fody, E.P. (1992) Clinical chemistry principles procedures correlations. 2nd Ed. (Philadelphia: J.B. Lippin Cott Co.), 281.
Farrell, C.E. (1984) “Electrolytes” in clinical chemistry theory. Analysis and correlation. The C.V. Mosby Company. Kaplan L.A., Pesce. A.J. (Ed), Chap 55, 1054.
Carl, A. Burtis and Edward, R. Ashwood (1986) Tietz Text book of clinical chemistry, W.B. Saunders, 579.
Carl, A, Burtis and Edward, R. Ashwood (1986) Tietz Text book of clinical chemistry, W.B. Saunders, 589.
Carl A Burtis and Edward, R. Ashwood (1999) Tietz Text book of clinical chemistry, W.B. Saunders (Ed 3rd), 1400.
Isselbacher, Braunwad, Wilson, Martin, Fanci and Kasper (1994) Harrison’s principles of internal medicine, 13th Ed. vol. 2, 2139.
Conceicao, S.C., Weightman, Doris, Smith, P.A. Luno, J. Ward, M.K. and Kerr, D.N.S. (1978) Serum ionized calcium concentration: Measurement versus calculation. B.M.J. vol. 1, 1103–1105.
Crottogins, A.J. and Sigguard, Anderson O. (1981) Plasma ionized calcium in the critically ill on total parental nutrition. Scand. J. Clin. Lab. vol. 41, 49.
Transhol, I. (1977) On the diagnosis of so called normally calcaemic hyperthyroidism. Acta. Med. Scand. vol. 202, 481.
Robertson, W.C. and Marshakk, R.W. (1981) Ionized calcium in body fluids. Crit. Rev. Clin. Lab. Sci. vol. 15, 85–125.
Burritt, M.F., Pierides, A.M. and offord, K.P. (1980) Comparative studies of total and ionized serum calcium values in normal subjects and patients with renal disease. Mayo Clin. Proc. vol. 55, 606–613.
Bhagavan, N.V. (2002) Medical biochemistry, 4th Ed, pg 874.
Ladenson, J.H., Lewis, J.W., McDonald, J.M., Slatopoisky, E. and Boyd, J.C. (1979) Relationship of free and total calcium in hyperglycemic conditions. J. Clin. Endocrinol. Metab. vol. 48, 393–397.
Ladenson, J.H. and Bowers, J.R.G.N. (1973) Free calcium in serum II. Rigor homeostatic control, correlations with total serum calcium and review of data on patients with distributed calcium metabolism. Clin. Chem. vol. 19, 575–582.
Toftaletti, J. (1986) Ionized calcium through its first decade: A review of the analytical aspects and clinical importance of ionized calcium measurements. NOVA Biomedical (Available from NOVA Biomedical Inc., 200 propects St., Walthan, M.A. 02254-9141).
James, C.B., John, W.C., Eduards, S. and Jack, H. Ladenson (1981) Parathyrin measured concurrently with free or total calcium in the differential diagnosis of hypercalcaemia. Clin. Chem. vol. 27/4, 574–579.
Thode, J.J., Jorgenson, B., Bhatia, H.M., Kjaerulf-Nielson, M., Bartels, P.D., Fogh-Anderson, N. and Siggard-Anderson, O. (1989) Comparison of serum total calcium, albumin-corrected total calcium and ionized calcium in 1213 patients with suspected calcium disorders. Scand. J. Clin. Lab. Invest. vol. 49 (3), 217–223.
Sorva, A. and Elfvings, Pohja P. and Tibis, R.S. (1988) Assessment of calcaemic status in geriatric hospital patients: Serum ionized calcium versus albumin-adjusted total calcium. Scand. J. Clin. Lab. Invest. vol. 48 (6), 489–494.
Editorial (1979) Serum calcium. Lancet I, 858.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sava, L., Pillai, S., More, U. et al. Serum calcium measurement: Total versus free (ionized) calcium. Indian J Clin Biochem 20, 158–161 (2005). https://doi.org/10.1007/BF02867418
Issue Date:
DOI: https://doi.org/10.1007/BF02867418