IDENTIFYING PARATHYROID HORMONE DISORDERS AND THEIR PHENOTYPES THROUGH A BONE HEALTH SCREENING PANEL: IT'S NOT SIMPLE...

To determine the utility of bone health screening panels in identifying disorders of parathyroid gland secretions.

A retrospective analysis of biochemical parameters in a bone health screening panel (BHSP) was conducted. Low and high cutoffs were applied to determine hypofunctioning and hyperfunctioning conditions related to parathyroid hormone. Clinical phenotypes of parathyroid gland abnormalities were determined using a combination of levels of calcium, 25-hydroxyvitamin D, and intact parathyroid hormone (iPTH). A PTH nomogram was applied to calculate the maximum expected PTH for existing levels of 25-hydroxyvitamin D. Medical records of patients were reviewed for clinical validation of biochemical findings.

Sixty-eight percent of subjects showed abnormal PTH secretion. Primary hyper- and hypoparathyroidism were detected in 1% (n = 5) and 0.4% (n = 2) of subjects, respectively. Normocalcemic hyperparathyroidism and hypercalcemia with inappropriately high-normal PTH were identified in 8.5% (n = 37) and 2% (n = 10) of subjects, respectively. All subjects with primary and normocalcemic hyperparathyroidism had higher measured PTH than calculated maximum PTH using the PTH nomogram. Secondary hyperparathyroidism and functional hypoparathyroidism were present in 18% (n = 88) and 39% (n = 194) of subjects, respectively. High prevalence of bone pains, renal stones, and low bone mineral density were identified in patients with abnormal PTH secretion.

Panel testing is useful in early diagnosis of metabolic bone disorders related to PTH. A BHSP helps identify normocalcemic hyperparathyroidism and hypercalcemia with inappropriately high PTH.

25OHD = 25-hydroxyvitamin D AKUH = Aga Khan University Hospital BHSP = bone health screening panel iPTH = intact parathyroid hormone maxPTH = maximum parathyroid hormone MBD = metabolic bone disease NCHPT = normocalcemic hyperparathyroidism PHPT = primary hyperparathyroidism PTH = parathyroid hormone SHPT = secondary hyperparathyroidism VDD = vitamin D deficiency.