Using an observational, retrospective, cross-sectional study design, the authors investigated the utility of measuring ionized (iCa) and total (tCa) serum calcium levels in the diagnosis of primary hyperparathyroidism. In 315 biochemistry cohort cases with PTH-dependent hypercalcemia, 130 (41%) had isolated ionized hypercalcemia at diagnosis. Similarly, in 143 patients with histologically proven parathyroid disease, 24% had isolated ionized hypercalcemia at diagnosis. They concluded that measurement of iCa is required to accurately assess calcium status and improve diagnostic accuracy.
Ong GS, Walsh JP, Stuckey BG, Brown SJ, Rossi E, Ng JL, et al