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Circulating immunoreactive parathyroid hormone levels in premature infants and the response to calcium therapy
Insights
Premature infants
Area of Science:
- Neonatal Physiology
- Endocrinology
- Pediatric Metabolism
Background:
- Neonatal hypocalcemia is a common complication in premature infants.
- The parathyroid hormone (PTH) plays a crucial role in calcium homeostasis.
- The etiology of hypocalcemia in prematurity is not fully understood.
Purpose of the Study:
- To investigate the relationship between serum calcium and immunoreactive parathyroid hormone (iPTH) levels in premature infants.
- To determine the parathyroid gland's response to hypocalcemia in this population.
- To explore potential factors contributing to hypocalcemia in premature infants.
Main Methods:
- Serum levels of iPTH, calcium, magnesium, and phosphorus were measured in 13 premature infants within the first 96 hours of life.
- Infants were monitored for hypocalcemia (defined as low serum calcium levels).
- A subset of hypocalcemic infants received calcium infusion, while others served as controls.
Main Results:
- Hypocalcemia at 12-24 hours of age was linked to significantly elevated mean serum iPTH levels.
- Untreated hypocalcemic infants showed persistently low calcium and increasing iPTH.
- Infants receiving calcium infusion demonstrated improved serum calcium and decreased iPTH levels.
- Serum iPTH levels were twofold higher in untreated infants compared to treated infants at 72 and 96 hours.
Conclusions:
- The parathyroid glands of premature infants demonstrate responsiveness to changes in serum calcium levels.
- Parathyroid insufficiency is unlikely to be the sole cause of hypocalcemia in prematurity.
- Other unidentified factors likely contribute to the development of hypocalcemia in premature infants.
Abstract:
Serum immunoreactive parathyroid hormone (iPTH), calcium, magnesium, and phosphorus levels were measured in 13 premature infants during the first 96 hours of life. Hypocalcemia at 12-24 hours of age was associated with a markedly elevated mean serum iPTH level. Six of the hypocalcemic infants received a continuous infusion of calcium while seven were not treated. In the untreated infants, the mean serum calcium remained in the hypocalcemic range while the serum iPTH progressively increased. By contrast, the mean serum calcium in the treated infants increased to 2.35 mmol/l at 96 hours of age and was accompanied by a decline in serum iPTH. At 72 and 96 hours, the mean serum iPTH was twofold greater in the untreated than in the treated infants. The results indicate that the parathyroid glands of premature infants respond to calcium signals and that a factor(s), other than parathyroid insufficiency, plays an etiologic role in the hypocalcemia of prematurity.