The development and assessment of methods for measurement of total, ultrafilterable and ionised serum calcium is given. An existing fluorimetric technique for total calcium has been automated and modified for routine use. A device for rapidly preparing serum ultrafiltrates has been developed and an electrometric method for ionised calcium measurement assessed. Values in normal subjects are given for all three fractions and compared with the findings of other workers.
References
1.
ArnoldD. E.StansellM. J.MalvinH. H.Measurement of serum ionic calcium using a specific ion electrode. Amer. J. Clin. Path.49 (1968) 627.
2.
BandrowskiJ. F.BensonC. L.Investigation of the use of calcium in the ultramicro fluorometric determination of calcium in serum. Clin. Chem.18 (1972) 1411.
3.
BordeauA. M.SachsC. Practical aspects of the measurement of ionised calcium in blood with a liquid membrane electrode. Le Pharmacien Biologiste6 (1970) 527.
4.
BreenM.FreemanS. The use of high centrifugal force in separating plasma calcium into its protein-bound and protein-free fractions. Clin. Chim. Acta.6 (1961) 181.
5.
ChanB. E.A semi-automated method for the estimation of ionic calcium activity and concentration biological solutions. Clin. Chim. Acta.37 (1972) 5.
6.
EttoriJ.SerogganS. M.Metal ions in biological systems. A determination of pM by spectrophotometry of metal indicators at two wavelengths. Arch. Biochem.78 (1958) 213.
7.
HansenS. O.TheodorsenL. The usefulness of an improved calcium electrode in the measurement of ionised calcium in serum. Clin. Chim. Acta.31 (1971) 119.
8.
HattnerR.S.JohnsonJ. W.BernsteinD.S.WashmanA.BrackmanJ. Electrochemical determination of apparent ionised serum calcium using a calcium-selective electrode: The method and values in normal humans and a comparison to total serum calcium. Clin. Chim. Acta.28 (1970) 67.
9.
LewinM. R.WillsM. R.BaronD. N.Ultramicro-fluorimetric determination of calcium in plasma. J. Clin. Path.22 (1969) 222.
10.
LokenH. F.HavellR. J.GordonG. S.WhittingtonS. L.Ultracentrifugal analysis of protein-bound and free calcium in human serum. J. biol. Chem.235 (1960) 3654.
11.
McLeanF. C.HastingsA. B., The state of calcium in the fluids of the body. The conditions affecting the ionisation of calcium. J. Biol. Chem.108 (1935) 285.
12.
MooreE. W.Ionised calcium in normal serum, ultra-filtrates and whole blood determined by ion exchange electrodes. J. Clin. Invest.49 (1970) 318.
13.
MundayK. A.MahyB. W. J.Determination of ultrafilterable calcium and magnesium on small quantities of plasma. Clin. Chim. Acta.10 (1964) 144.
14.
OreskesI.HirschG.DouglasK. S.KupferS. Measurement of ionised calcium in human plasma with a calcium selective electrode. Clin. Chim. Acta.21 (1968) 303.
15.
PaulsenL. Comparison between total CO2-content in plasma/serum from blood collected with or without paraffin oil. Scand. J. Clin. Lab. Invest.9 (1957) 402.
16.
PedersonK. O.Determination of calcium fractions of serum. I. Scand. J. Clin. Lab. Invest.24 (1969) 69.
17.
PedersonK. O.Determination of calcium fractions of serum. Ill. Scand. J. Clin. Lab. Invest.25 (1970) 223.
18.
PutmanJ. M.A routine method for determining plasma ionised calcium and its application to the study of congenital heart disease. Clin. Chim. Acta.37 (1972) 33.
19.
RobertsonW. G.PeacockM. New techniques for the separation and measurement of the calcium fractions of normal human serum. Clin. Chim. Acta.20 (1968) 315.
20.
RobinsonB. H. B.RushtonM. L.SammonsH. G. To be published. (1973).
21.
RoseG. A.Determination of the ionised and ultra-filterable calcium of normal human plasma. Clin. Chim. Acta.2 (1957) 227.
22.
RoseG. A.A simple and rapid method for the measurement of plasma ultrafilterable and ionised calcium. Clin. Chim. Acta.37 (1972) 343.
23.
RossJ. W.Jr.Solid-state and liquid membrane ion-selective electrodes. In DurstR. A. (Ed.), Ion-selective electrodes. United States, Department of Commerce, National Bureau of Standards. Special publication. 314 (1969) 57.
24.
RushtonM. L.The state of calcium in the serum of human subjects with particular reference to patients with chronic renal failure. Ph.D. Thesis, University of Birmingham (1972).
25.
RushtonM. L.SammonsH. G.RobinsonB. H. B.A study of calcium absorption using an automated fluorimetric assay procedure. Clin. Chim. Acta.35 (1971) 5.
26.
SchwartzH. D.McConvilleB. C.ChristophersonE. F.Serum ionised calcium by specific ion electrode. Clin. Chim. Acta.31 (1971) 97.
27.
WalserM. Ion association. Interactions between calcium, magnesium, inorganic phosphate, citrate and protein in normal human plasma. J. Clin. Invest.40 (1961) 723.
