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Plasma concentrations of vitamin D metabolites in premature infants
Insights
Premature infants receiving vitamin D supplements can achieve high plasma levels of 1,25-dihydroxyvitamin D (1,25-(OH)2D) within weeks of birth. Their 24,25-dihydroxyvitamin D (24,25-(OH)2D) levels remained low compared to adults.
Area of Science:
- Neonatal nutrition
- Endocrinology
- Pediatric research
Background:
- Premature infants have unique nutritional needs.
- Vitamin D metabolism is crucial for infant development.
- Understanding vitamin D metabolite dynamics in preterm infants is essential.
Purpose of the Study:
- To measure plasma concentrations of key vitamin D metabolites in premature infants.
- To compare these levels with those in healthy adults.
- To assess the capacity of premature infants to produce 1,25-dihydroxyvitamin D.
Main Methods:
- Plasma levels of 25-hydroxyvitamin D, 1,25-(OH)2D, and 24,25-(OH)2D were measured in 28 premature infants and 17 adults.
- Infants received 500 IU/d vitamin D with a diet low in calcium and phosphorus.
- Measurements were taken during the first 5-10 weeks of life.
Main Results:
- Infant 25-hydroxyvitamin D levels increased significantly from day 1 to 5-10 weeks.
- 1,25-(OH)2D levels in infants rose rapidly, reaching high levels by 1-4 weeks, comparable to adults.
- 24,25-(OH)2D concentrations were consistently lower in infants than adults.
Conclusions:
- Healthy premature infants can achieve high plasma 1,25-(OH)2D levels.
- Vitamin D supplementation supports adequate 1,25-(OH)2D production in preterm infants.
- Further research into 24,25-(OH)2D levels and their implications in premature infants is warranted.
Abstract:
The plasma concentrations of 25-hydroxyvitamin D (OHD), 1,25-(OH)2D and 24,25-(OH)2D were determined in 28 healthy premature infants (median gestational age 33, range 28-36 wk; and median birth weight 1880, range 900-2350 g) during the first 5-10 wk of life, and in a reference group of 17 young adults. The infants received a vitamin D supplement of 500 IU/d and a diet low in calcium (Ca) and phosphorus (P) compared with that of corresponding intrauterine accretion rates. The median 25-OHD concentration increased from 11 (range 6-30) ng/ml at 1 d to 27 (range, 15-41) ng/ml by 5-10 wk of age (P less than 0.01). 1,25-(OH)2D concentrations at age 1 d were similar to the adult levels (median 37, range 8-64 versus 35, range 18-58 pg/ml), but increased significantly within 1 wk to 48 (26-156) pg/ml (P = 0.01), and between 1 and 3-4 wk of age to 104 (58-203) pg/ml (P less than 0.01). The levels at 5-10 wk were similar to the 3-4 wk value. 24,25-(OH)2D concentrations were persistently low compared with the adult levels (medians 0.4-0.5, range less than 0.3-2.1 versus 1.7, range 0.4-2.0 ng/ml, P less than 0.01). The relative concentrations, expressed as the ratio of 24,25-(OH)2D to 25-OHD, were comparable to those of the adults at birth, but decreased significantly within 2 wk. The data demonstrate that healthy premature infants can produce high plasma levels of 1,25-(OH)2D.