Endocrine: Parathyroid Glands

Parathyroid Glands

• 4 tiny glands with rich blood supply, interact with blood calcium
• Exclusive for calcium metabolism
• Produce hormones PTH
• Measurement of PTH in blood indicates its function
• Control calcium in blood and bones

Calcium Function

• Provides electrical energy for the nervous system
• Conducts electricity in the nervous system
• Stabilizes neuromuscular excitability, making nerves less sensitive to stimuli
• Provides energy for cells to contract in the muscular system
• Strengthens skeletal system by making bones strong
• Bones serve as calcium storage system

Hyperparathyroidism

• Excess PTH secretion
• Causes increased bone resorption/osteoporosis, hypercalcemia, and hypercalciuria
• Types: Primary and Secondary
• Primary: Tumor of parathyroid gland, failure, or chronic renal failure
• Secondary: Compensatory response to hypocalcemia often due to chronic renal failure

Primary Hyperparathyroidism

• Caused by parathyroid adenoma (one or more glands)
• Leads to increased skeletal resorption, release of Ca2+ and Pi from bone
• Increases Ca2+ and Pi absorption from small intestine
• Enhances Ca2+ reabsorption and inhibits Pi reabsorption from renal, causing increased urine Pi excretion
• Results in increased ECF calcium and decreased ECF phosphate

Secondary Hyperparathyroidism

• Caused by chronic renal failure and malabsorption
• Elevated PTH levels
• Long-term activation causes hyperplasia of glands, loss of sensitivity to circulating calcium
• Autonomous secretion of PTH even with normal calcium levels

Complications of Hyperparathyroidism

• Death due to cardiac and neurological dysfunctions
• Hypercalcemia, hypercalciuria, and osteoporosis

Treatment of Hyperparathyroidism

• Medical emergency for severe hypercalcemia
• Use diuretics to increase calcium excretion
• Use drugs to inhibit bone resorption
• Surgical removal of tumor or ectopic secretion due to tumor

Hypoparathyroidism

• Abnormal or low PTH levels
• Etiology: thyroid surgery, autoimmunity, genetic mechanism, and Di George syndrome
• Clinical findings: depressed calcium, increased phosphate, decreased bone resorption, and hypocalciuria
• Treatment: calcium and vitamin D replacement therapy, risk of kidney stones

Complications of Hypoparathyroidism

• Paresthesia, muscle cramps, and spasms (tetany)
• Fatigue, headaches, bone pain, and insomnia
• Severe irregularities in normal heart beat
• Spasm of airways causing respiratory failure

This quiz covers the functions of parathyroid glands, calcium metabolism, and calcium's role in the nervous system and muscle contractions.