Serum PTH reference values established with an automated 3rd-generation assay in vitamin D-replete subjects with normal renal function. Consequence for the diagnosis of primary hyperparathyroidism and the classification of dialysis patients

• Published in: European journal of endocrinology Vol. 174; no. 3; pp. 315 - 323
• Main Authors: Souberbielle, Jc, Massart, Catherine, Brailly-Tabard, Sylvie, Cormier, Catherine, Cavalier, Etienne, Delanaye, Pierre, Chanson, Philippe
• Format: Journal Article
• Language: English
• Published: Oxford Univ. Press 01.03.2016
• Subjects: Biochemistry, Molecular Biology; Life Sciences; Molecular biology; dialysis; parathyroid hormone; reference values; vitamin D; primary hyperparathyroidism
• ISSN: 0804-4643; 1479-683X
• DOI: 10.1530/EJE-15-0595

Objective - To determine parathyroid hormone (PTH) reference values in French healthy adults, taking into account serum 25-hydroxyvitamin D (25OHD), renal function, age, gender, and BMI. Participants and main biological measurements - We studied 898 healthy subjects (432 women) aged 18-89 years with a normal BMI and estimated glomerular filtration rate (eGFR), 81 patients with surgically proven primary hyperparathyroidism (PHPT), and 264 dialysis patients. 25OHD and third-generation PTH assays were implemented on the LIAISON XL platform. Results - Median PTH and 25OHD values in the 898 healthy subjects were 18.8  ng/l and 23.6  ng/ml respectively. PTH was lower in subjects with 25OHD ≥30  ng/ml than in those with lower values. Among the 183 subjects with 25OHD ≥30  ng/ml, those aged ≥60 years (n=31) had higher PTH values than younger subjects, independent of 25OHD, BMI, and eGFR (P<0.001). Given the small number of subjects aged ≥60 years, we adopted the 95% CI of PTH values for the entire group of 183 vitamin D-replete subjects (9.4-28.9  ng/l) as our reference values. With 28.9  ng/l as the upper limit of normal (ULN) rather than the manufacturer's ULN of 38.4  ng/l, the percentage of PHPT patients with 'high' PTH values rose to 90.1% from 66.6% (P<0.001), and 18.6% of the dialysis patients were classified differently in view of the KDIGO target range (two to nine times the ULN). Conclusion - When only subjects with 25OHD ≥30  ng/ml were included in the reference population, the PTH ULN fell by 22.4%, diagnostic sensitivity for PHPT improved, and the classification of dialysis patients was modified.