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 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 Results Primary Secondary Decrease PTH 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 .