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Hypercalcemia and nephrocalcinosis in patients with congenital lactase deficiency
T Saarela1, S Similä, M Koivisto
1Department of Pediatrics, University of Oulu, Finland.
Insights
Congenital lactase deficiency in infants can cause hypercalcemia and nephrocalcinosis. A lactose-free diet effectively resolves hypercalcemia, though some renal issues may persist.
Area of Science:
- Pediatric Gastroenterology
- Metabolic Disorders
- Nephrology
Background:
- Congenital lactase deficiency is a rare genetic disorder affecting lactose digestion.
- Infants with this condition may present with various clinical manifestations.
- The association between congenital lactase deficiency and hypercalcemia is not well-established.
Purpose of the Study:
- To describe clinical findings in infants diagnosed with congenital lactase deficiency.
- To investigate the prevalence of hypercalcemia and nephrocalcinosis in these patients.
- To evaluate the effect of a lactose-free diet on hypercalcemia and renal parameters.
Main Methods:
- Retrospective case series of 11 infants diagnosed with congenital lactase deficiency.
- Clinical data collection including age at diagnosis, serum calcium levels, and renal ultrasonography.
- Assessment of clinical outcomes following dietary intervention (lactose-free diet).
Main Results:
- Eleven infants diagnosed between 6 and 88 days of age.
- Hypercalcemia was present in 70% (7/10) of infants at diagnosis.
- Medullary nephrocalcinosis was observed in 5 of 7 infants undergoing renal ultrasonography; hypercalcemia resolved within a week of a lactose-free diet.
- Long-term follow-up revealed persistent hypercalciuria in one patient and nephrocalcinosis in three patients.
Conclusions:
- Congenital lactase deficiency is associated with a high incidence of hypercalcemia and nephrocalcinosis in infants.
- A lactose-free diet is an effective treatment for resolving hypercalcemia in these patients.
- The underlying mechanism of hypercalcemia may involve metabolic acidosis or the direct effect of undigested lactose on calcium absorption.
Abstract:
We describe 11 infants with congenital lactase deficiency, whose age at diagnosis varied from 6 to 88 days. At the time of admission, 7 of 10 infants had hypercalcemia. Five of the seven infants for whom renal ultrasonography was performed at the time of diagnosis had medullary nephrocalcinosis. Hypercalcemia ceased within a week of the start of a lactose-free diet. At the time of reevaluation, at the ages of 2 to 10 years, one of the patients still had hypercalciuria and nephrocalcinosis was still present in 3 of 11 patients. The mechanism of hypercalcemia is unclear but may be related to metabolic acidosis or may be promoted by the lactose effect (i.e., by nonhydrolyzed lactose that has a direct enhancing effect on calcium absorption in the ileum).