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Serum concentrations of 25-hydroxyvitamin D in rickets of extremely premature infants
Insights
Extremely premature infants are at high risk for rickets due to low vitamin D levels. Ensuring at least 400 IU of vitamin D daily is crucial for these vulnerable infants.
Area of Science:
- Neonatology
- Pediatric Nutrition
- Endocrinology
Background:
- Rickets is a significant concern in premature infants.
- Low serum 25-hydroxyvitamin D (25-OHD) levels are common in this population.
- Extremely premature infants present unique challenges in vitamin D metabolism.
Purpose of the Study:
- To investigate the incidence and potential causes of rickets in extremely premature infants.
- To evaluate the role of vitamin D intake and metabolism in the development of rickets.
- To determine optimal vitamin D supplementation strategies for at-risk infants.
Main Methods:
- Retrospective analysis of nine extremely premature infants diagnosed with rickets.
- Assessment of radiographic and biochemical markers of rickets.
- Measurement of serum 25-hydroxyvitamin D concentrations.
- Evaluation of vitamin D and calcium intake from formulas.
Main Results:
- All nine infants developed rickets at a mean age of 12.6 weeks.
- Mean serum 25-OHD levels were significantly low (<3.6 ng/ml).
- Infants were fed low-calcium formulas and had low average daily vitamin D intake.
- Hypothesized increased 25-OHD utilization and decreased production in this group.
Conclusions:
- Extremely premature infants require higher vitamin D intake (at least 400 IU daily) due to impaired production and potential increased utilization.
- Low-calcium intake may exacerbate vitamin D deficiency.
- Monitoring serum 25-OHD and radiographic findings is essential for at-risk infants.
Abstract:
Nine premature infants developed radiographic and biochemical rickets at a mean +/- SD of 12.6 +/- 2.8 weeks of age. Serum 25-hydroxyvitamin D concentrations were all low, with a mean of less than 3.6 +/- 2.1 ng/ml. The mean average daily intake of vitamin D since birth had been 300 +/- 181 IU, and the mean average daily intake during the week of diagnosis was 587 +/- 313 IU. All of the infants were extremely premature (mean weight 948 +/- 153 gm, mean gestation 27.7 +/- 1.1 weeks), and were being fed either a low-calcium "human milk-like" formula or a soy formula. It is postulated that low-calcium intake may have increased 25-OHD utilization in the face of a decreased ability of the extremely premature infant to produce 25-OHD. Because of multiple factors leading to both decreased production and possible increased utilization of 25-OHD, such infants have an increased requirement for vitamin D to maintain normal serum 25-OHD concentrations, and daily intakes of at least 400 IU vitamin D orally must be assured. Serum 25-OHD measurements and radiographs may be important in following infants at risk.