INTRODUCTION: Parathyroid hormone (PTH) and vitamin D are essential components in mineral metabolism. Our aims were to estimate the thresholds of 25-hydroxyvitamin D [25(OH)D] and estimated glomerular filtration rate (eGFR) that inhibit PTH, establish PTH reference intervals (RIs), and the stratify need based on age and gender. MATERIALS AND METHODS: We conducted a cross-sectional study on participants older than 18 years. Segmented regressions (SR) were performed to determine the thresholds of 25(OH)D and eGFR in relation to PTH levels. Multivariate regression was used to evaluate the associations between PTH and 25(OH)D, gender, age, eGFR, and season. To establish the PTH RIs, extreme percentiles were calculated. RESULTS: A total of 2794 subjects were analyzed (women, 77.56%). Multivariate regression indicated that age, gender, 25(OH)D, and eGFR explained PTH variation. SR demonstrated that PTH stabilized when eGFR>
46.64mL/min/1.73m CONCLUSION: Our study suggests a stabilization point in PTH with an eGFR>
46.64mL/min/1.73m