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Hypercalcemia in children: an overview
1Department of Pediatrics, School of Medicine, Kumamoto University, Japan.
Insights
Familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NHPT) are linked to calcium-sensing receptor gene mutations. These genetic variations can cause severe hypercalcemia in children, impacting calcium regulation.
Area of Science:
- Pediatric Endocrinology
- Genetics
- Calcium Metabolism
Background:
- Hypercalcemia in children, especially serum calcium over 15 mg/dL, presents a significant health risk.
- Familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NHPT) are distinct conditions affecting calcium homeostasis.
- Recent discoveries include the isolation of a complementary DNA for an extracellular calcium-sensing receptor.
Purpose of the Study:
- To explore the association between FHH and NHPT.
- To investigate the role of calcium-sensing receptor gene mutations in these conditions.
- To discuss other causes of pediatric hypercalcemia, including vitamin D-related issues.
Main Methods:
- Characterization of FHH by high serum calcium, low urine calcium, and normal parathyroid hormone (PTH).
- Description of NHPT as a severe, often fatal, hypercalcemic condition requiring early intervention.
- Identification of three mutations in the calcium-sensing receptor gene in individuals with FHH and NHPT.
Main Results:
- Heterozygotes for FHH mutations may exhibit intermittent hypercalcemia.
- Homozygotes for FHH mutations may present with NHPT.
- The calcium-sensing receptor gene mutations provide a genetic link between FHH and NHPT.
Conclusions:
- Mutations in the calcium-sensing receptor gene are implicated in both FHH and NHPT.
- Genetic analysis offers insights into the pathogenesis of severe pediatric hypercalcemia.
- Understanding these genetic links is crucial for diagnosis and management of calcium disorders in children.
Abstract:
Hypercalcemia occurs in children of all ages. A serum calcium level over 15 mg/dL can be life-threatening. The association between familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NHPT) has been discussed. FHH is characterized by a high serum calcium concentration, relatively low urine calcium excretion, and an inappropriately normal parathyroid hormone (PTH) concentration. On the other hand, NHPT is a rare disease characterized by markedly increased serum calcium (15 mg/dL) and PTH concentrations, and is fatal without parathyroidectomy early in life. Recently, a complementary DNA encoding an extracellular calcium-sensing receptor has been isolated. Furthermore, three mutations in the receptor gene in FHH and NHPT individuals have been described. Thus, heterozygotes and homozygotes of FHH may have an intermittent hypercalcemia and NHPT, respectively. Vitamin D-related hypercalcemia, and vitamin D intoxication and immobilization are also discussed.