EC Orthopaedics

Review Article Volume 17 Issue 2 - 2026

Multifactorial Regulation and Limitation of the PTH-Vitamin D Axis

Rosini Sergio1, Molfetta Francesco2, Rosini Stefano3, Palermo Augusto4 and Molfetta Luigi5*

1Biomaterial Research Center, Livorno, Italy

2DINOGMI Department, School of Medical and Pharmaceutical Sciences, University of Genoa, Genoa, Italy

3Smile-Restyle, Livorno, Italy

4Head Prosthetic Surgery Unit, Istituto Clinico Humanitas Bergamo Gavazzeni, Bergamo, Italy

5DISC Department, School of Medical and Pharmaceutical Sciences, Research Center of Osteoporosis and Osteoarticular Pathologies, University of Genoa, Genoa, Italy

*Corresponding Author: Molfetta Luigi, Professor, DISC Department, School of Medical and Pharmaceutical Sciences, Research Center of Osteoporosis and Osteoarticular Pathologies, University of Genoa, Genoa, Italy.
Received: July 31, 2025; Published: February 05, 2026




Parathyroid hormone (PTH) and vitamin D (Vit D) play a central role in the regulation of calcium-phosphate metabolism through a complex feedback system involving calcitriol, FGF23-Klotho signaling, renal function, and adipocyte-derived leptin.

While maximal suppression of PTH at serum 25-hydroxyvitamin D [25(OH)D] concentrations around 30 ng/mL has been widely adopted as a marker of Vit D sufficiency in adults, growing evidence indicates substantial interindividual variability influenced by age, genetic background, renal function, adiposity, and calcium intake. In children and adolescents, the relationship between PTH and 25(OH)D appears linear and lacks a clear inflection point, questioning the applicability of adult thresholds.

 Moreover, leptin and declining renal function further modulate PTH secretion independently of vitamin D status. This review highlights the multifactorial regulation of the PTH/Vit D axis and underscores the limitations of defining universal thresholds for Vit D sufficiency based solely on PTH suppression.

 Keywords: Parathyroid Hormone; Vitamin D; Leptin; Homeostasis; BMI

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Molfetta Luigi., et al. “Multifactorial Regulation and Limitation of the PTH-Vitamin D Axis”. EC Orthopaedics  17.2 (2026): 01-05.

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