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Neonatal parathyroid secretion and renal receptor maturation in premature infants
Insights
Premature infants show adult-level parathormone (PTH) response early in life. However, their kidneys exhibit a delayed response to exogenous PTH, potentially explaining neonatal hypocalcemia and hyperphosphatemia.
Area of Science:
- Neonatology
- Endocrinology
- Pediatric Nephrology
Background:
- Neonatal hypocalcemia and hyperphosphatemia are common in premature infants.
- The role of parathormone (PTH) in neonatal mineral homeostasis is not fully understood.
- Premature infants exhibit unique physiological adaptations compared to full-term neonates.
Purpose of the Study:
- To investigate parathormone levels and renal response in premature infants during the first week of life.
- To evaluate the maturation of renal tubule function in response to exogenous parathormone.
- To explore the potential link between renal parathormone receptor development and neonatal mineral imbalances.
Main Methods:
- Studied 16 premature infants with normal trophicity during their first week of life.
- Measured serum intact parathormone (IPTH) levels.
- Assessed renal tubule maturation by evaluating urinary 3':5'-cyclic adenosine monophosphate (cAMP) excretion after exogenous parathormone (PTE) administration.
Main Results:
- IPTH levels in premature infants reached adult levels by the first day of life.
- Urinary cAMP excretion showed a delayed and diminished response to PTE in premature infants compared to adults, particularly in lower-birth-weight infants.
- The renal response to PTE was significantly lower in premature infants, suggesting delayed receptor development.
Conclusions:
- Prematurity does not appear to affect the parathormone response itself, as levels are comparable to adults early on.
- The delayed renal response to parathormone in premature infants suggests an immature renal parathormone receptor system.
- This developmental delay in renal parathormone receptor function may contribute to neonatal hypocalcemia and hyperphosphatemia in premature infants.
Abstract:
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.