Parathyroid hormone (PTH)

Released by the parathyroid gland, an endocrine gland adjacent to the Thyroid gland

Increase Calcium in the circulation
-Increases release from bone (resorption)
-Increases absorption from kidneys
-Increases absorption from intestines

Diseases of the parathyroid gland:

1. Hypoparathyroid (low PTH)

• Reduced Calcium in the circulation
• Nerves
  -Increased excitability leads to muscle twitches and spasms
• Cardiac muscle
  -Reduced cardiac output
  -Different from skeletal muscle because cardiac muscle has little intracellular Calcium

2. Hyperparathyroid (elevated PTH)

• PTH stimulates Calcium release from bones
  - can lead to osteoporosis
• Increased Calcium in the circulation (hypercalcemia)
  -can cause increased cardiac contractions
  - and, increased incidence of kidney stones