November 1971

Factors Affecting Plasma Calcium Concentration During Hemodialysis

Author Affiliations

Columbia, Mo

From the Department of Medicine, Division of Nephrology, University of Missouri Medical Center, Columbia.

Arch Intern Med. 1971;128(5):769-773. doi:10.1001/archinte.1971.00310230099009

Plasma concentrations of calcium often increase during hemodialysis. To evaluate the mechanisms involved, total (Ca) and ionized (Ca++) calcium, protein, pH, Pco2, and sodium (Na+) were measured in plasma (P) at the beginning and end of 17 six-hour coil dialyses using bath with 5.27 ± 0.04 mg/100 ml of Ca++. Simultaneously, ultrafiltrates (UF) collected directly from coils (after isolating and draining the cannister) were analyzed for Ca, Ca++, and Na+. Increases in plasma Ca reflected mainly increases in protein-bound calcium (secondary to bath hemoconcentration of protein and increased binding per gram of protein) without an increase in plasma Ca++ or complexed Ca. With increases in plasma pH and protein concentration, (UF/P Na+)2 decreased only slightly suggesting minimal changes in net protein anionic concentration and Gibbs-Donnan effects.