Principle causes of hypocalcaemia in childhood
| Parathyroid hormone deficiency (low PTH levels) |
| I. Parathyroid aplasia/hypoplasia or abnormal PTH production |
| As part of 22q11 deletions |
| 10p13 deletion |
| CHARGE syndrome |
| X linked hypoparathyroidism (1 family in the world to date) |
| Autosomal dominant hypoparathyroidism |
| Autosomal recessive hypoparathyroidism |
| Syndrome of hypoparathyroidism, deafness, renal dysplasia (HDR) |
| II. Type 1 autoimmune polyendocrinopathy |
| III. Infiltrative lesions such as Wilson’s disease, thalassaemia |
| III. Mitochondrial DNA mutations e.g. Kearns Sayre syndrome |
| IV. Magnesium deficiency |
| V. Neck surgery |
| Altered “set point” (normal or low normal parathyroid hormone levels) |
| VI. Calcium sensing receptor activating mutation |
| Hypocalcaemia associated with increased PTH production (raised PTH levels) |
| VII. Gsα and other signalling defects |
| e.g. pseudohypoparathyroidism |
| VIII. Vitamin D deficiency |
| Nutritional |
| Malabsorption |
| IX. Calcium deficiency |
| X. Impaired vitamin D metabolism |
| Enzyme deficiency—defects of the 1 alpha hydroxylase gene (vitamin D dependent rickets type I) |
| End organ resistance to vitamin D (vitamin D dependent rickets type II) |
| XI. Renal failure |
| XII. Magnesium deficiency (low and high PTH levels have been reported) |
| XII. Osteopetrosis |