Interaction of calcium ions with serum albumin in chronic renal failure.
In order to study the effect of the uremic environment on serum calcium-albumin interaction, ten adult subjects with chronic renal failure (creatinine clearances below 20 ml/min) and five adult normal subjects, had their serum ionic calcium (Orion SS-20) determined at three different serum pH values. At similar serum protein levels, the correlations between serum ionic calcium pH were: (a) normals: number of pairs = 15, r = -0.90, p less than 0.01, Ca2+ = 4.54-0.484 pH. (b) uremics: number of pairs=15, r=-0.97, p less than 0.01, Ca2+=4.02-0.429 pH. These regressions were similar as far as the slopes (Fslope=0.62, p greater than 0.05) but had different intercepts (Fintercepts=64.34, p less than 0.01). These results confirm that uremics, when compared to normal subjects, present an ionic hypocalcemia at any level of serum pH. They also show that serum calcium-albumin interaction is normal in uremia. In view of the above results, it can be suggested that, among several possible causes, alterations in the binding-affinity of calcium ions to serum albumin can be excluded as an additional factor of secondary hyperparathyroidism in uremia.
Interaction of calcium ions with serum albumin in chronic renal failure. In order to study the effect of the uremic environment on serum calcium-albumin interaction, ten adult subjects with chronic renal failure (creatinine clearances below 20 ml/min) and five adult normal subjects, had their serum ionic calcium (Orion SS-20) determined at three different serum pH values. At similar serum protein levels, the correlations between serum ionic calcium pH were: (a) normals: number of pairs = 15, r = -0.90, p less than 0.01, Ca2+ = 4.54-0.484 pH. (b) uremics: number of pairs=15, r=-0.97, p less than 0.01, Ca2+=4.02-0.429 pH. These regressions were similar as far as the slopes (Fslope=0.62, p greater than 0.05) but had different intercepts (Fintercepts=64.34, p less than 0.01). These results confirm that uremics, when compared to normal subjects, present an ionic hypocalcemia at any level of serum pH. They also show that serum calcium-albumin interaction is normal in uremia. In view of the above results, it can be suggested that, among several possible causes, alterations in the binding-affinity of calcium ions to serum albumin can be excluded as an additional factor of secondary hyperparathyroidism in uremia.