Mechanisms:
(1) congenital absence of the parathyroid gland or defect in parathyroid hormone (PTH)
(2) acquired removal or destruction of the parathyroid glands
(3) end organ resistance to the effect of parathyroid hormone
(4) impaired release of parathyroid hormone from the parathyroid gland
Congenital absence of the parathyroid gland or defect in PTH::
(1) X-linked hypoparathyroidism
(2) autosomal hypoparathyroidism
(3) DiGeorge's syndrome
(4) mutations in parathyroid hormone gene
Acquired removal or destruction of the gland can occur in:
(1) surgical removal (total thyroidectomy, removal of all the parathyroid glands)
(2) iron overload (hemochromatosis, post-transfusion hemosiderosis)
(3) Wilson's disease
(4) autoimmune polyendocrinopathy (polyglandular syndrome)
(5) metastatic carcinoma to the neck
(6) therapy with radioactive iodine
Resistance to the effect of parathyroid hormone:
(1) pseudohypoparathyroidism Type I or II
(2) hypomagnesemia
Impaired release of parathyroid hormone:
(1) hypomagnesemia
(2) respiratory alkalosis
(3) mutation in the calcium sensor in the parathyroid tissue with reduced sensitivity
