Table 2

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