Intact parathyroid hormone levels during pregnancy, in healthy term neonates and in hypocalcemic preterm infants.
We measured parathyroid hormone levels in pregnant and nonpregnant women and at 1, 2 and 5 days of life in healthy term neonates and in hypocalcemic preterm infants using a new immunoradiometric assay which measures only biologically active intact parathyroid hormone and by a mid-molecule parathyroid hormone radioimmunoassay. During pregnancy intact and mid-molecule parathyroid hormone levels did not show any modification and were not different from parathyroid hormone levels of nonpregnant age-matched controls. Serum calcium and phosphorus levels did not vary during each trimester of pregnancy. In cord serum intact and mid-molecule parathyroid hormone values were low in both term and preterm infants. In term neonates intact and mid-molecule parathyroid hormone levels peaked on day 1; in preterm infants intact parathyroid hormone levels peaked on day 1 while mid-molecule parathyroid hormone values peaked on day 2. Intact parathyroid hormone levels showed a more marked increase in preterm (19-fold) than in term neonates (7.5-fold) on day 1. Our data do not confirm the previously reported "physiologic" hyperparathyroidism in pregnancy. Moreover we found a normal parathyroid gland responsiveness to decreasing serum calcium levels in the first days of life in term and preterm infants. Our results suggest that measurement of intact parathyroid hormone 1-84 by immunoradiometric assay in the first days of life is a more sensitive index of parathyroid gland secretory function than the measurement of middle or carboxyl-terminal parathyroid hormone fragments allowing the detection of the dynamic changes of parathyroid hormone which occur in hypocalcemic preterm infants.
Saggese
G
G
Vitamin D Laboratory, University of Pisa, Italy.
Baroncelli
G I
GI
Bertelloni
S
S
Cipolloni
C
C
D000328:Adult; D002118:Calcium / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006801:Humans; D006996:Hypocalcemia / Q000097:blood*; D015592:Immunoradiometric Assay / Q000379:methods; D007231:Infant, Newborn / Q000097:blood*; D007235:Infant, Premature, Diseases / Q000097:blood*; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood; D011247:Pregnancy / Q000097:blood*; D011863:Radioimmunoassay
D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium