We employed a new IRMA intact PTH assay (Allegro, Nichols Institute), which is able to detect the biologically active form of the hormone, in order to evaluate the secretory pattern of PTH in normal newborns and in preterm infants with ENH. Intact PTH levels were low in cord serum (n.v. in chidren 38.0 ± 12.5 pg/ml) in both HTN and in ENH. In HTN we found a significant rise of PTH levels with a peak at day 1° (+7.5 fold) and a slight fall at day 5° (Table). In ENH intact PTH values increased more (+19 fold) than in HTN and showed a decrease when normal calcium levels were achieved (Table).Values as mean ± ISD.°significantly different from birth (p<0.001);*significantly different from birth and HTN (p<0.001). Our data showed that in ENH intact PTH levels rose in first-hours of life when calcium decrease as in HTN demonstrating a normal responsiveness of parathyroid glands to hypocalcemia also in preterm infants.
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