Parathyroid hormone (PTH)
- Secreted from chief cells when serum calcium (Ca) is low
- 3 actions
- Increase osteoclastic bone reabsorption
- Increase intestinal reabsorption
- Increase calcitriol (D3), tubular reabsorption, phosphate excretion
Etiology
- Chronic kidney disease (MCC), Vitamin D deficiency, thyroid surgery, idiopathic
- Di George syndrome – mental impairment, cataract, calcified basal ganglia
- Pseudohypoparathyroidism – end organ resistance to hormone (like T2 diabetes)
- Drugs – bisphosphonates, calcitonin
(master calcium hormone regulator) - Hypoalbuminemia
Pathology
- homeostasis defects, Secondary hyperphosphatemia
Clinical features
- Neuromuscular irritability, psychosis, paraesthesia, cramps,
- Chvostek and trousseau signs
- Severe hypoPTH – papilloedema (optic disk swelling), QT syndrome
- rickets/osteomalacia
Diagnosis
- clinical, serum calcium, PTH/Vitamin D, hyperphosphatemia
- serum magnesium – hypomagnesemia > hypoparathyroidism
Treatment
- Cholecalciferol
- Alfacalcidol – for chronic kidney disease
- Emergency – Calcium gluconate (I.V)