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.

b Institute of Clinical Biochemistry and Diagnostics University Hospital Hradec Kralove Hradec Kralove Czech Republic

Department of Paediatrics Faculty of Medicine Hradec Kralove Charles University Prague University Hospital Hradec Kralove Hradec Kralove Czech Republic

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