The Use in Clinical Practice of Parathyroid Hormone Normative Values Established in Vitamin D-Sufficient Subjects

Abstract

We have found recently that excluding subjects with low serum 25OHD has a significant impact on the PTH reference range (10 -46 ng/liter instead of 10 -65 ng/liter with the same assay). However, before being used routinely, this new range had to be clinically validated. We thus reviewed the chart of 708 consecutive osteopenic patients who were referred to our unit for a biological exploration in search of secondary causes for their low bone mass. They were classified into two groups. Group 1 (n ‫؍‬ 360) included the patients for whom no reasons for high PTH were found after examination of their chart. Group 2 (n ‫؍‬ 348) included patients with one of the following potential reasons for an increased PTH concentration: hyperor hypocalcemia, normocalcemic primary hyperparathyroidism (PHPT), renal hypercalciuria, vitamin D insufficiency, chronic renal failure, use of bisphosphonates, and any chronic disease known to potentially alter calcium metabolism. Among the 360 group 1 patients, 15 (4.2%) had a serum PTH level more than 46 ng/liter, which is not different from the theoretical rate of 3% of normal subjects whose serum PTH may be above the 97th centile of the reference ( 2 ‫؍‬ 2.8; NS). Forty-two group 2 patients had a surgically proven PHPT. Among these, serum PTH was <65 ng/liter in 17 (40.5%) and tion that still remains undetected in many patients. It induces mild secondary hyperparathyroidism with a subsequent increase in bone turnover and, at least in the elderly, an enhanced risk of osteoporotic fracture, mainly at cortical sites (1). It could be defined by the serum concentration of 25OHD below which serum PTH starts to increase in a population (2). We recently proposed to include only normal subjects without low serum 25OHD concentration to establish a reference range for serum PTH (3). By doing this in healthy subjects aged 60 -79 yr, we found with a widely used PTH assay that the highest normal concentration at P Ͻ 0.05 (46 ng/liter) was consistently lower than what is generally accepted with the same assay (65 ng/liter) (4). However, before being used routinely, this new reference range had to be clinically validated. This is the goal we aimed to achieve in the present study by showing that our proposed PTH reference range induced a decrease in the number of false negative values [i.e. less normal serum PTH levels in surgically proven primary hyperparathyroidism (PHPT)] without an increase in the rate of false positive values (i.e. no more than 3% of high values in normocalcemic patients without any potential reason to have an increased serum PTH concentration). Patients and Methods PatientsWe reviewed the medical chart of 708 consecutive osteopenic/porotic patients (74 premenopausal women, 552 menopausal women and 82 men) aged 59.2 Ϯ 13.4 yr. They were referred to our bone/calcium metabolism unit over a 1-yr period (from July 17, 2000, to July 16, 2001 by their primary care physician in search of secondary causes for their low bone mass. The patients came on a single morning to our unit after an over...

Renal stones and calcifications in patients with primary hyperparathyroidism: associations with biochemical variables

“…After exclusion (Fig. 1), the study consisted of 177 hypercalcaemic patients with a mean of two to four calcium measurements and plasma intact PTH in the upper one-third of the normal range or elevated (P-PTH O5 pmol/l) (31). The patients were then divided into two groups, with or without renal calcification on spiral CT scan, and the blood and urine samples were compared.…”

Plasma 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and parathyroid hormone in familial hypocalciuric hypercalcemia and primary hyperparathyroidism

“…(27,28). After parathyroid surgery, histopathological examination revealed adenoma(s) in 119 of the patients, hyperplasia in 26, and combined adenoma and hyperplasia in 2 patients.…”

Reference Range for Serum Parathyroid Hormone

“…They found that when 25-OHD levels were considered, the upper limits of "normal" of PTH declined from 65 pg/mL to 46 pg/mL in subjects with 25-OHD levels above 30 nmol/L, a change that would have clinical ramifications. Subsequently, these investigators validated their proposal of 46 pg/ mL as the upper limit of the reference range of PTH by a review of medical records in patients with osteopenia (26). In an editorial accompanying their publication, however, their conclusions were questioned (27).…”