Parathyroid hormone – reference values and association with other bone metabolism markers in very low birth weight infants – pilot study

Abstract

Purpose: The aim of this pilot study was to estimate physiological parathyroid hormone (PTH) levels and their relationship with bone metabolism parameters in otherwise healthy preterm newborns with birth weight 1000–1500 g.

Methods: PTH, 25(OH)D, S-Ca, S-P, and ALP were analysed from blood samples obtained from 20 preterm infants once a week up to the 36th gestational week.

Results: Of the total 134 examined serum samples for PTH levels, the estimated range was 1.6–9.3 pmol/l (15.1–87.7 pg/ml). No statistically significant correlation of PTH level with that of S-Ca, S-P, or ALP was observed, except for the 56th day of life (p = .03; Rho = 0.76; n = 8). From the second month of life, there was a statistically significant relationship only between PTH and 25(OH)D (Rho = −0.71, p ≤ .0001). In our cohort, vitamin D deficiency (20 ng/ml) occurred in 75% at birth and at 30% in the 36th gestational week.

Conclusions: The physiological range indicated by the measurements was close to the reference limits for adults (1–7 pmol/l; 9.4–66 pg/ml). PTH level above this range can be considered as hyperparathyroidism in preterm neonates.

Keywords:

• Metabolic bone disease
• parathyroid hormone
• preterm newborn
• vitamin D

Acknowledgements

The authors are grateful to Ian McColl MD, PhD, for assistance with the manuscript.

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by University Hospital Hradec Kralove, Czech Republic project MH CZ – DRO [UHHK, 00179906], and by Charles University in Prague, Faculty of Medicine in Hradec Králové, Czech Republic.