Related Experiment Videos
Hypophosphatemic rickets accompanying congenital microvillous atrophy
K Kagitani1, T Yamamoto, K Miki
1Department of Pediatrics, Faculty of Medicine, Osaka University, Osaka, Japan.
Insights
This study details a unique case of hypophosphatemic rickets in a child with congenital microvillous atrophy. Intestinal phosphate loss was identified as the primary cause, successfully treated by adjusting parenteral nutrition phosphate levels.
Area of Science:
- Pediatric Gastroenterology
- Endocrinology
- Nutritional Science
Background:
- Congenital microvillous atrophy (CMA) is a rare neonatal enteropathy characterized by severe diarrhea and malabsorption.
- Hypophosphatemic rickets, a disorder causing bone deformities due to low phosphate levels, typically has distinct causes like X-linked mutations.
Observation:
- An 11-year-old boy with diagnosed CMA since infancy presented with leg pain, hypophosphatemia, elevated 1,25-dihydroxyvitamin D, and hypercalciuria.
- Phosphate balance studies revealed significant intestinal phosphate wasting exceeding renal losses.
- Phosphate deficiency in this patient was primarily driven by excessive loss through the gut.
Findings:
- The patient exhibited rickets, confirmed radiographically, alongside biochemical markers of phosphate deficiency.
- Treatment involved increasing phosphate concentration in total parenteral nutrition (TPN), which successfully healed the rickets.
- This case presents a novel form of hypophosphatemic rickets where intestinal phosphate malabsorption is the key pathogenic factor.
Implications:
- This case highlights intestinal phosphate wasting as a potential, previously unrecognized cause of hypophosphatemic rickets, particularly in patients with severe enteropathies.
- Findings suggest that careful assessment of phosphate balance, including fecal losses, is crucial in managing complex gastrointestinal disorders.
- The successful therapeutic response to adjusted TPN phosphate levels offers a targeted treatment strategy for similar cases.
Abstract:
This report concerns an 11-year-old boy who manifested hypophosphatemic rickets associated with congenital microvillous atrophy (CMA). He had been suffering from vomiting and severe diarrhea from the first day of life and had been treated with total parenteral nutrition (TPN) since he was 67 days old. At 4 years of age, intestinal biopsy resulted in a diagnosis of CMA. He was admitted to our hospital complaining of leg pain at the age of 11. Laboratory data revealed hypophosphatemia, elevated serum 1, 25-dihydroxyvitamin D (1,25(OH)2D) levels, and hypercalciuria. A roentgenogram showed rickets in the extremities. A balance study of phosphate in urine and stool indicated that the amount of phosphate leaking into the stool was greater than that into the urine. Moreover, the total amount of phosphate leaking from both the intestine and kidney exceeded the amount of phosphate intake from TPN. The rickets was healed by increasing the phosphate concentration in TPN. This case is different from X-linked hypophosphatemic rickets but similar to hereditary hypophosphatemic rickets with hypercalciuria (HHRH) in terms of hypercalciuria and elevated serum 1,25(OH)2D levels. The effectiveness of phosphate treatments used here is also similar to that used for HHRH. However, this type of hypophosphatemic rickets is unique in that phosphate leaking into the intestine plays an important role in its pathogenesis.