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Growth velocity and plasma alkaline phosphatase activity in the preterm infant
Insights
In preterm infants, higher alkaline phosphatase activity correlates with decreased growth, unlike in older children. This finding is crucial for understanding infant bone health and rickets.
Area of Science:
- Neonatology
- Pediatric Endocrinology
- Biochemistry
Background:
- The relationship between growth and plasma alkaline phosphatase (ALP) activity varies between preterm infants and older individuals.
- Biochemical rickets is prevalent in preterm infants.
Purpose of the Study:
- To investigate the correlation between growth velocity and plasma ALP activity in preterm infants during the first 12 postnatal weeks.
- To examine the association of plasma ALP activity with vitamin D metabolites, calcium, inorganic phosphate, and parathyroid hormone levels.
Main Methods:
- Serial measurements of growth velocity and plasma ALP activity in 18 preterm infants.
- Assays for plasma calcium, inorganic phosphate, vitamin D metabolites (including 1,25-dihydroxycholecalciferol), and parathyroid hormone at 3 and 6 weeks.
- Comparison between infants with ALP activity within and exceeding the preterm reference range.
Main Results:
- A significant negative correlation (r = -0.37; P < 0.005) was observed between growth and plasma ALP activity.
- Infants with elevated ALP activity showed lower plasma 1,25-dihydroxycholecalciferol and inorganic phosphate at 3 weeks.
- Caloric intake did not differ between groups.
Conclusions:
- In preterm infants, elevated plasma ALP activity is associated with reduced growth, contrasting with older populations.
- The findings suggest a distinct biochemical profile related to bone metabolism in preterm infants with high ALP activity.
- Increased plasma ALP activity in preterm infants may indicate biochemical rickets and impaired growth.
Abstract:
The relationship between growth and plasma alkaline phosphatase activity differs in the preterm infant when compared with older children and adolescents. 18 preterm infants were studied over the first 12 postnatal weeks; growth velocity and plasma alkaline phosphatase activity were measured serially. Plasma calcium, inorganic phosphate, the vitamin D metabolites and parathyroid hormone were assayed at a median age of 3 and 6 weeks. There was an overall significant negative correlation between growth and plasma alkaline phosphatase activity (r = -0.37; P less than 0.005); this was more marked in a group where the plasma alkaline phosphatase activity exceeded the preterm reference range. Plasma 1,25-dihydroxycholecalciferol and inorganic phosphate were lower in this group at 3 weeks but not at 6 weeks when compared with infants where plasma alkaline phosphatase activity did not exceed the reference range. There was no difference in caloric intake between the groups. In the preterm infant biochemical rickets is common and unlike older children and adolescents an increase in plasma alkaline phosphatase activity correlates with decreased rather than increased growth.