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Background: Establishing assay-specific reference intervals for parathyroid hormone (PTH) is essential for appropriate clinical interpretation. However, data on PTH reference intervals in Korean adults using the Roche Elecsys assay are limited.
Methods: We retrospectively analyzed data from Korean adults who underwent simultaneous measurement of PTH and related biochemical markers between January 2020 and December 2023. Reference intervals were estimated using CLSI EP28 non-parametric methods in the total cohort and in subgroups with normal biochemical parameters, with additional assessment of 25-hydroxyvitamin D [25(OH)D] status.
Results: During the four-year study period, we analyzed results from 509 individuals (101 men and 408 women; median age, 44.4 years [IQR, 35.5 - 54.9]). The central 95% reference interval for serum PTH in all subjects was 16.7 - 64.2 pg/mL. Among 461 individuals with normal biochemical parameters, the interval was 17.3 - 61.8 pg/mL, and after exclusion of outliers (449 subjects), the final reference interval was 17.3 - 53.6 pg/mL (90% CI: lower limit, 16.3 - 18.0; upper limit, 51.8 - 57.7). No significant differences were observed by gender or age; therefore, partitioning was not required. PTH concentrations varied significantly by vitamin D status, with higher values in individuals with 25(OH)D < 20 ng/mL compared with those with sufficient levels (≥ 30 ng/mL, p < 0.001). The derived intervals were broadly consistent with the manufacturer-provided reference intervals, although the upper limit tended to be higher in vitamin D-deficient subjects.
Conclusions: This study verified Roche Elecsys PTH reference intervals in Korean adults using an indirect approach and confirmed the importance of considering vitamin D status for interpretation, providing practical guidance for clinical laboratories.
DOI: 10.7754/Clin.Lab.2025.250845
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