PTH: Redefining Reference Ranges in a Healthy Population—The Role of Interfering Factors and the Type of Laboratory Assay

Abstract

Introduction. Parathyroid hormone (PTH) is a linear peptide constituted by 84 amino acids and active in its 1-84 form, but a wide range of PTH forms produced by its post-transcriptional modifications are present in blood. Many assays with different specificities are commercially available. e aim of our study was to compare a 2 nd and 3 rd generation in healthy population in order to better define the reference range in the healthy population residing in our region. Materials and Methods. 108 subjects (53 females and 55 males) referring to the transfusion donor were enrolled in the study centre in April 2016 and underwent PTH levels measurements with a 3 rd generation kit (chemiluminescent immunoassay DiaSorin Liaison) and with a 2 nd generation kit (immunoradiometric assay Total Intact PTH Assay (Coated Tube), Scantibodies). Also calcium, phosphate, creatinine, and 25OHD3 were measured. A questionnaire on lifestyle and dietary habits was obtained. Results. e median PTH values obtained with the 2 nd generation assay and the whole 3 rd generation assay were 20.26 pg/ml and 23.11 pg/ml, respectively. Bland-Altman method showed substantial concordance between the two PTH assays, although with an overestimation of the 3 rd generation method over the 2 nd generation method. ere was no correlation between 3 rd generation PTH and 25OHD3 and creatinine. Calcium was negatively correlated with PTH only when measured with 3 rd generation kit. Conclusions. On the basis of our data, obtained from healthy subjects, we can conclude that the reference range used by our laboratory was too narrow and was necessary to reestablish normal ranges according to our population. is is useful to avoid hyperparathyroidism misdiagnosis.

Parathyroid carcinoma: impact of preoperative diagnosis on the choice of surgical procedure

“…Although several reports have suggested different iPTH thresholds for distinguishing between benign and malignant parathyroid lesions [12,13], the sample sizes in these reports might be insufficient to adequately represent the entire carcinoma population. Moreover, iPTH values could vary depending on the measurement method [14]. It might be more appropriate to determine the threshold based on the upper normal limit, rather than the absolute amount of iPTH.…”

Calcium status assessment at the population level: Candidate approaches and challenges

“…PTH is most often measured by immunoassays, but variations in the assay methodology have made it challenging to set reference ranges, which would also need to consider vitamin D status and time of day of sample collection. [82][83][84] For a populationbased survey, there are also challenges associated with measuring a peptide, which is sensitive to degradation, although this has been done successfully in some national nutrition surveys. 84 One of the most significant factors affecting intestinal calcium absorption is 1,25(OH) 2 D, and the concentration of this active metabolite in a vitamin D replete individual is influenced by calcium intake, PTH concentrations, and serum phosphate levels.…”

“…PTH is most often measured by immunoassays, but variations in the assay methodology have made it challenging to set reference ranges, which would also need to consider vitamin D status and time of day of sample collection. 82 , 83 , 84 For a population‐based survey, there are also challenges associated with measuring a peptide, which is sensitive to degradation, although this has been done successfully in some national nutrition surveys. 84 …”

“…Levels of PTH have been measured in some national nutrition surveys 77–81 and have been inversely correlated with calcium intake, 77,79 although there are a number of challenges that would need to be addressed. PTH is most often measured by immunoassays, but variations in the assay methodology have made it challenging to set reference ranges, which would also need to consider vitamin D status and time of day of sample collection 82–84 . For a population‐based survey, there are also challenges associated with measuring a peptide, which is sensitive to degradation, although this has been done successfully in some national nutrition surveys 84 …”

New Generation of Meso and Antiprogestins (SPRMs) into the Osteoporosis Approach

“…PTH acts as enhancer of Ca resorption in bones and kidneys, respectively. PTH also stimulates production of activated 1,25-dihydroxyvitamin D (1,25(OH)2D), which mobilizes intestinal calcium absorption [85,86]. PTH probably serves the regulation of bone remodeling rather than overall skeletal mass.…”