TY - JOUR
T1 - Relationship of free and total calcium in hypercalcemic conditions
AU - Ladenson, Jack H.
AU - Lewis, John W.
AU - McDonald, Jay M.
AU - Slatopolsky, Eduardo
AU - Boyd, James C.
PY - 1979/3
Y1 - 1979/3
N2 - An assessment of free and total calcium measurements was made in 691 patients with suspected hypercalcemia or disorders often associated with hypercalcemia. In 18.9% of the 1049 specimens analyzed from nine different patient groups, a different impression of hypercalcemia was obtained depending on whether the free or total calcium was considered. Analysis of the ratio of free to total calcium indicated that there are two main factors which influence the distribution of calcium in the serum of hypercalcemic patients: the concentrations of albumin and parathyroid hormone. A lowered albumin concentration accounted for the altered distribution of calcium in patients with malignancies and partially accounted for the altered distribution in patients postrenal transplantation. In patients with confirmed primary hyperparathyroidism a higher ratio of free to total calcium was found, which could not be explained by alterations in protein, albumin, pH, or CO2 content but was related to parathyroid hormone concentration. Free calcium appears to be a slightly better indicator of elevated calcium states than total calcium. Measurements of free calcium should be particularly useful in patients with altered albumin concentration, with multiple myeloma in whom a calcium-binding protein could be present, after renal transplantation, and with suspected hyperparathyroidism and normal or slightly elevated total calcium values.
AB - An assessment of free and total calcium measurements was made in 691 patients with suspected hypercalcemia or disorders often associated with hypercalcemia. In 18.9% of the 1049 specimens analyzed from nine different patient groups, a different impression of hypercalcemia was obtained depending on whether the free or total calcium was considered. Analysis of the ratio of free to total calcium indicated that there are two main factors which influence the distribution of calcium in the serum of hypercalcemic patients: the concentrations of albumin and parathyroid hormone. A lowered albumin concentration accounted for the altered distribution of calcium in patients with malignancies and partially accounted for the altered distribution in patients postrenal transplantation. In patients with confirmed primary hyperparathyroidism a higher ratio of free to total calcium was found, which could not be explained by alterations in protein, albumin, pH, or CO2 content but was related to parathyroid hormone concentration. Free calcium appears to be a slightly better indicator of elevated calcium states than total calcium. Measurements of free calcium should be particularly useful in patients with altered albumin concentration, with multiple myeloma in whom a calcium-binding protein could be present, after renal transplantation, and with suspected hyperparathyroidism and normal or slightly elevated total calcium values.
UR - https://www.scopus.com/pages/publications/0018371630
U2 - 10.1210/jcem-48-3-393
DO - 10.1210/jcem-48-3-393
M3 - Article
C2 - 429492
AN - SCOPUS:0018371630
SN - 0021-972X
VL - 48
SP - 393
EP - 397
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 3
ER -