Big data-based parathyroid hormone (PTH) values emphasize need for age correction
Lara Bessa Campelo Pinheiro Cavalcante, Cynthia Brandão, Maria Izabel Chiamolera, Rosa Paula M. Biscolla, Jin Lü, Pedro Russo, J. Morgado, C. M. A. de Francischi Ferrer, José Gilberto H. Vieira
Abstract
Abstract Purpose We aimed to study the relationship between aging and increased parathyroid hormone (PTH) values. Methods We performed a retrospective cross-sectional study with data from patients who underwent outpatient PTH measurements performed by a second-generation electrochemiluminescence immunoassay. We included patients over 18 years of age with simultaneous PTH, calcium, and creatinine measurements and 25-OHD measured within 30 days. Patients with glomerular filtration rate < 60 mL/min/1.73 m 2 , altered calcemia, 25-OHD level < 20 ng/mL, PTH values > 100 pg/mL or using lithium, furosemide or antiresorptive therapy were excluded. Statistical analyses were performed using the RefineR method. Results Our sample comprised 263,242 patients for the group with 25-OHD ≥ 20 ng/mL, that included 160,660 with 25-OHD ≥ 30 ng/mL. The difference in PTH values among age groups divided by decades was statistically significant (p < 0.0001), regardless of 25-OHD values, ≥ 20 or ≥ 30 ng/mL. In the group with 25-OHD ≥ 20 ng/mL and more than 60 years, the PTH values were 22.1–84.0 pg/mL, a different upper reference limit from the reference value recommended by the kit manufacturer. Conclusion We observed a correlation between aging and PTH increase, when measured by a second-generation immunoassay, regardless of vitamin D levels, if greater than 20 ng/mL, in normocalcemic individuals without renal dysfunction.