Thyroid hormones calcium metabolism effects

Four small parathyroid glands are embedded on the posterior surface of the thyroid gland as it wraps around the trachea. Parathyroid hormone (PTH, parathormone) is the principal regulator of calcium metabolism. Its overall effects include ... 

The thyroid secretes two types of hormones iodine-containing amino acids (thyroxine and triiodothyronine) and a peptide (calcitonin). Thyroxine and triiodothyronine have very general effects on growth, development, and metabolism. Calcitonin is important in calcium metabolism and is discussed in Chapter 41. This chapter describes the drugs used in the treatment of hypothyroidism and hyperthyroidism (Figure 38-1). 

The absorption of calcium, sodium, potassium, chloride, magnesium, and iron is thought to be influenced by the thyroid hormone. The results of the studies of the effect of thyroxine on electrolyte metabolism are often contradictory and difficult to interpret however, it seems accepted that thyroxine affects phosphorus metabolism by increasing the excretion of the metal in both urine and stools. 

This hormone is secreted by the parathyroid glands, which are four in number and lie on the posterior surface of the thyroid gland. The exact manner in which the hormone exerts its action upon calcium and phosphorus metabolism has not been proved satisfactorily, but the most immediate effect of administration of parathyroid extract which has been generally observed is an increased excretion of phosphorus in the urine, which is accompanied by a lowering of the serum inorganic phosphate. The increase in the urinary phosphate excretion has been ascribed by Harrison and Har-... 

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