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MLAB 2401: Clinical Chemistry Keri Brophy-Martinez. Parathyroid gland. Anatomy. The parathyroid glands are four or more small glands located on the posterior surface (back side) of the thyroid gland. Function & Regulation.
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MLAB 2401: Clinical ChemistryKeri Brophy-Martinez Parathyroid gland
Anatomy • The parathyroid glands are four or more small glands located on the posterior surface (back side) of the thyroid gland.
Function & Regulation • Maintain the body’s calcium level for proper functioning of nervous and muscular systems • In situations of low blood calcium, the parathyroid senses this and releases PTH hormone that work to increase calcium levels High blood Ca+ level Low blood Ca+ level Breakdown of bone matrix decreases Breakdown of bone matrix increases Normal blood Ca+ Level
Parathyroid hormone (PTH) • Sole hormone secreted by parathyroid, from the chief cells • Also known as parathyrin
PTH • Action • Raise serum concentration of calcium • How? • Promotes reabsorption of calcium from bone • Increases kidney tubule reabsorption of calcium by a process where phosphate and bicarbonate is excreted • Activates vitamin D, assists in absorption in the gut
Calcitonin • Produced by the thyroid • Action • Increase bone formation • Inhibit bone breakdown • Lowers blood calcium levels • Antagonistic to PTH
Disorders • Hyperparathyroidism • Causes • Benign adenoma • Hyperplasia of tissue in response to chronic calcium loss • Secretion of PTH from malignant non-endocrine tumor
Hyperparathyroidism • Results • Increased PTH • Increased urine and serum calcium • Decreased serum phosphorous • Increased urine phosphorous • Kidney problems (stones) • Bone problems (demineralization)
Hypoparathyroidism • Causes • Primary • Idiopathic • Secondary • Thyroid/ parathyroid surgery • Autoimmune diseases • Results • Decrease PTH • Decreased serum calcium • Increased serum phosphorous
References Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical Chemistry: Techniques, principles, Correlations. Baltimore: Wolters Kluwer Lippincott Williams & Wilkins. http://www.cedars-sinai.edu/Patients/Programs-and-Services/Head-and-Neck-Cancer-Center/Treatment/Parathyroidectomy.aspx http://www.teachpe.com/gcse_anatomy/bones.php Sunheimer, R., & Graves, L. (2010). Clinical Laboratory Chemistry. Upper Saddle River: Pearson .