Parathyroid Disease
Chief cells of the parathyroid gland produce PTH, which increases calcium and decreases phosphate. It does this by:
Increases bone osteoclast activity, which releases Ca and Ph
Increases gut Ca reabsorption
Increases kidney Ca (and reduces Ph) reabsorption
Activates Vit D - increases absorption of Ca and Ph in the gut
Hyperparathyroidism:
Primary - Excess PTH due to a tumour. This leads to hypercalcaemia, which presents with stones, bones, groans, and psychiatric moans (see hypercalcaemia notes).
Secondary - Excess PTH in response to low calcium because of kidney, liver, or bowel disease. Causes of this include Vit D deficiency, CKD, and Ca malabsorption.
Tertiary - Prolonged secondary hyperparathyroidism, which leads to gland hyperplasia and excessive PTH relaease even after correction of hypocalcaemia. Cause of this is long-standing kidney disease.
Management - Surgical removal of gland(s)
Hypoparathyroidism:
Primary - Autoimmune gland failure, which leads to hypocalcaemia. This presents with SPASMODIC (see hypocalcaemia notes).
Secondary - Caused by Surgery, Radiation, Hypomagnesaemia (Mg needed for PTH secretion)
Pseudohypoparathyroidism - Failure of target response to normal levels of PTH. Presents with short stature and fingers, and hypocalcaemia.
Management - Calcium and Vit D supplementation