Renal cyclic AMP response to parathyroid hormone in premature hypocalcemic infants

Linarelli, Louie G.; Bobik, Caroline; Bobik, J.

doi:10.1016/s0022-3476(74)80797-3

Cited by 7 publications

(4 citation statements)

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“…There is evidence in human newborns that a transient pseudohypoparathyroidism-like state is present at birth and over the first several days of life (9,26,27), probably reflecting an immaturity of the receptor-adenyl cyclase system in renal tubular as well as bone cells. Prostaglandin E compounds, which are capable of inhibiting PTH induced adenyl cyclase activity (6), may contribute to hypocalcemia by reducing renal phosphate clearance and enhancing neonatal hyperphosphatemia.…”

Section: Discussionmentioning

confidence: 99%

Parathormone and Perinatal Calcium Homeostasis

et al. 1979

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Summawand Rudd (49) have observed mean PTH concentrations in cord Plasma measured the first parathormone (PTH) and calcium concentrations were in 309 specimens collected from 190 newborns during 7 days of life. The patient material consisted of 51 preterm, 130 term, and 9 postterm infants, including 22 infants of diabetic mothers (IDM), 38 infants with hypocalcemia, and 25 asphyxiated infants. PTH was detectable, although in low concentrations, in cord blood samples despite the presence of elevated calcium concentrations. Postpartum, PTH concentrations in term, appropriate for gestational age (AGA) infants remained low during the first 2 days of life; a significant ( P < 0.05) and sustained increase in plasma hormone levels was noted starting on day 3. PTH concentrations in IDM and preterm infants remained low for 3 days and a significant hormone increase did not occur until day 4.Hypocalcemia was common in IDM and asphyxiated infants; these infants accounted for two-thirds of all hypocalcemic infants. The profde of plasma calcium in IDM during the fust week of life was different than that of any other group of infants. Plasma calcium concentrations remained depressed over this period of time and exhibited a temporary drop on day 4 accompanied by an increase in plasma PTH levels. Asphyxiated infants exhibited low plasma calcium concentrations, despite PTH levels that were significantly ( P < 0.007) higher than those of age-matched term AGA newborns. SpeculationBasal PTH secretion is present at birth, several days before the parathyroid glands appearto become responsive to hypocalcemia. Furthermore, in cord blood PTH is detectable in spite of elevated calcium concentrations. The present observatiois suggest that nonsuppressible PTH secretion, previously described in short-term animal ex~eriments. also occurs in the human fetus ex~osed to long-standing intrauterine hypercalcemia, with the implication that PTH secretion in man may be regulated by control mechanisms in addition to calcium feedback. There is anatomical and pharmacologic evidence to implicate the autonomic nervous system in this control.Hypocalcemia is a frequent problem in early postnatal Life (1 1, 20, 37, 47). Between 1970 and 1971,44 of 1390 newborns (3.2%) delivered at Harbor General Hospital, UCLA, presented with socalled "first day hypocalcemia" defmed as serum calcium levels of 5 7 mg/dl during the first 36-48 hr of life (32). Two-thirds of these infants were premature (gestation less than 38 weeks). The etiology of first day hypocalcemia remains unclear. A number of authors (17,19,46) (1 17 k 17), but were unable to detect any correlation between serum-ionized calcium on the one hand and PTH levels on the other in either maternal, cord, or infant blood between birth and age 7 days. David and Anast (13) reported similar results, yet they did observe an increase in plasma PTH in 23 of 36 infants beyond age 48 hr, and this increase correlated with a gradual rise of the low neonatal calcium concentrations toward normal. Finally, there are conflic...

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Section: Discussionmentioning

confidence: 99%

Parathormone and Perinatal Calcium Homeostasis

et al. 1979

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“…Qucstions remain about the ability of PTH target tissues in prenlature infants to respond to PTH and vitamin D. In tern1 infants, urinary cyclic AMP and urinary phosphate excretion increase in a parallel fashion to PTH increase in the first 3 days of life (23) and exogenous PTH can produce an increase in cyclic urinary AMP and phosphate excretion (23). However, in hypocalcemic premature infants, no cyclic AMP rcsponse was seen to exogenous PTH (22). Tsang ei nl.…”

Section: Discussionmentioning

confidence: 99%

Serial Measurements of Serum Calcium, Magnesium, Parathyroid Hormone, Calcitonin, and 25-Hydroxy-Vitamin D in Premature and Term Infants during the First Week of Life

et al. 1977

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CONCLUSIONPercutaneous absorption of testosterone from the ventral forearm in newborn rhesus monkeys was determined as a mcasure of skin barrier function. Skin absorption at a concentration of 4 and 40 pg/cm2 were, respectively, 22.5 r 2.2% (SD) and 6.8 r 2.1% of the applied dose, values which were not significantly different ( P > 0.05) from those of adult rhesus and which were similar to man. If the absorption is expressed as micrograms absorbed systemically, then the amounts are 0.9 and 2.7 pg/cm2 area of skin, a 3-fold increase in systemic absorption per 10-fold increase in topical dose. Occlusion of a dose of 4 0 pg/ cm2 enhanced absorption to 14.7%.The ratio of surface area (square centimeters) to body weight (kilograms) in the newborn is 3 times that in the adult. Therefore, given equal application area of skin per newborn and adult, the systemic availability in the newborn also becomes 3-fold when based on kilograms of body weight. With a different ratio of skin surface to body weight, the therapeutic ratio probably is lower in the newborn than in the adult when the compound is applied topically. This difference between newborn and adult in systemic availability after topical application may help explain some of the toxicity reported in newborns. Printed in U.S.A.Pediat. Res. 11: 739-744 (1977) Calcium magnesium calcium homeostasis parathyroid hormone cord, sera serum calcitonin 25-hydroxy-vitamin D Serial Measurements of Serum SummaryThe mean 2 SEM of the cord, 48-hr, and 7-day values for serum calcium, magnesium, liuman calcitonin (IICT), parathyroid hormone (PTH), and 25-hydroxy-vitamin D (25-OHD) for preniature and term infants can be seen in Table 1.Mean cord calcium concentrations were similar for term and premature infants. Serum calcium concentrations fell in both tern1 and premature infants at 4 8 hr, but decreased more in the premature infants (froni 10.23 & 0.30 to 8.74 2 0.19 mg/dl) than in the term infants (froni 10.5 + 0.26 to 9.6 2 0.23 mgldl).Serum calcium values increased from 4 8 hr to 7 days in both groups, and there was no significant difference between term and preniature infants' seruni calcium concentrations (10.6 2 0.28 and 10.12 + 0.3 mg/dl, respectively) at that time. There was no significant difference between ter~ii and premature cord serum magnesium concentrations. Seru~ii magnesium concentrations increased siniilarly by 4 8 hr in both groups and reniained at these concentrations at 7 days of life. Serum H C T concentrations were elevated above normal adult levels (71.9 2 6.6 pglml,

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“…With regard to parathyroid secretion, published reports appear contradic tory (4,12). In addition, little work has been done on the sensitivity of the renal parathyroid receptor as evaluated by urinary elimination of 3':5'-cyclic adenosine monophosphate (cAMP) (8). It thus appeared interesting to perform a simultaneous study in the 1st week of prema ture infant life of both parathyroid secretion and the sensitivity of its renal receptor using the effect of exogenous parathormone (PTE) on urinary elimination of cAMP.…”

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confidence: 99%

Neonatal Parathyroid Secretion and Renal Receptor Maturation in Premature Infants

Mallet¹,

Basuyau²,

Brunelle³

et al. 1978

Neonatology

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16 premature infants with normal trophicity were studied during the 1st week of life using serum parathormone (IPTH) dosage and evaluation of renal tubule maturation by the effect of exogenous parathormone (PTE) on urinary elimination of 3′:5′-cyclic adenosine monophosphate (cAMP). As of the 1st day, IPTH levels reached or surpassed those in the adult. Prematurity thus does not appear to influence parathormone response. Given the specificity of the dosage antiserum, it appears reasonable that the PTH detected is biologically active. After PTE, urinary elimination of cAMP does not appreciably increase until the 6th day, while still remaining much lower than adult levels. The lower the weight of the premature infant, the less intense the response of the kidney. It thus seems possible that the later development of renal parathormone receptor in the premature infant may be a factor responsible for neonatal hypocalcemia with hyperphosphatemia.

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Renal cyclic AMP response to parathyroid hormone in premature hypocalcemic infants

Cited by 7 publications

References 0 publications

Parathormone and Perinatal Calcium Homeostasis

Parathormone and Perinatal Calcium Homeostasis

Serial Measurements of Serum Calcium, Magnesium, Parathyroid Hormone, Calcitonin, and 25-Hydroxy-Vitamin D in Premature and Term Infants during the First Week of Life

Neonatal Parathyroid Secretion and Renal Receptor Maturation in Premature Infants

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