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[Phosphorus-calcium metabolism and plasma 25-hydroxycholecalciferol in intestinal malabsorption]
Insights
Children with malabsorption show lower calcium levels and thinner bones when jejunal mucosa is damaged. Intestinal cell integrity is key, more so than vitamin D levels, in causing calcium malabsorption.
Area of Science:
- Pediatric Gastroenterology
- Nutritional Science
- Bone Metabolism
Context:
- Malabsorption syndromes in children can lead to various nutritional deficiencies and bone health issues.
- Vitamin D status is crucial for calcium absorption and bone mineralization.
- Seasonal variations can influence vitamin D levels due to skin synthesis.
Purpose:
- To investigate the relationship between jejunal mucosa integrity, vitamin D status, and bone health parameters in children with suspected malabsorption.
- To assess the impact of season on these parameters.
- To determine the primary factors contributing to calcium malabsorption.
Summary:
- A study of 104 children (0-15 years) with suspected malabsorption found lower 25-hydroxycholecalciferol (25-OH-CC) levels in winter, particularly with jejunal mucosal atrophy.
- Children with jejunal atrophy had lower serum calcium levels, independent of 25-OH-CC levels.
- Cortical bone thickness decreased with jejunal mucosal damage, suggesting impaired calcium absorption due to compromised intestinal integrity is more critical than vitamin D deficiency.
Impact:
- Highlights the critical role of jejunal epithelial cell integrity in calcium absorption in pediatric malabsorption syndromes.
- Underscores that impaired intestinal absorption, rather than solely vitamin D deficiency, significantly impacts bone health in these children.
- Provides insights into the complex interplay of nutrition, intestinal health, and bone metabolism in pediatric malabsorption.
Abstract:
One hundred and four children aged 0-15 years, with suspicion of malabsorption were studied. They had a proximal jejunal biopsy and, at the same time, the following measurements: 25-hydroxycholecalciferol (25-OH-CC), calcium, phosphorus and serum alkaline phosphatase, bone age on X-ray of the left hand and wrist, cortical thickness of the 2nd, 3rd, 4th metacarpal bones. For the analysis of the results, the patients were divided into two groups according to the season (winter vs. summer). None of the patients in either group had clinical or radiological signs of rickets. The following results were obtained: 1. The 25-OH-CC serum levels were significantly lower during the winter than during the summer months. This was observed more frequently in the cases with atrophy of the jejunal mucosa. 2. During the summer, the 25-OH-CC serum levels were not different in the cases with normal or pathological mucosa. This demonstrates the importance of the skin synthesis of vitamin D during the summer months. 3. The mean of the serum calcium levels was significantly lower in the group of children with atrophy of the jejunal mucosa than in children with normal intestinal biopsy. The serum calcium levels were not correlated with the serum 25-OH-CC levels. 4. The serum phosphorus levels were significantly lowered during the winter months in the children aged 0-3 years with pathological jejunal biopsy. 5. The serum alkaline phosphatase levels were lowered in cases of total atrophy of the jejunal epithelium cells. 6. Cortical thickness of the metacarpal bones becomes thinner with the progression of the alteration of the jejunal epithelium cells, independently of season or age. However, only the group of children aged 0-3 years studied during the winter months and with total atrophy of the jejunal mucosa have a significantly diminished cortical thickness of the metacarpal bones. The lowering of the calcium levels and the decrease of the cortical thickness are probably secondary to an impaired intestinal absorption of calcium. In the syndrome of malabsorption, the integrity of the jejunal epithelial cells seems to play a more important role than a vitamin D deficiency in the genesis of this calcium malabsorption.