parathyroid gland

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Related to parathyroid: parathyroid gland, parathyroid hormone, parathyroid adenoma, Parathyroid Scan

Parathyroid gland

An endocrine organ usually associated with the thyroid gland and possessed by all vertebrates except the fishes. In response to lowered serum calcium concentration, a hormone is produced which promotes bone destruction and inhibits the phosphorus-conserving activity of the kidneys. See Thyroid gland

Common positions of human parathyroid glands on the posterior aspect of the thyroidenlarge picture
Common positions of human parathyroid glands on the posterior aspect of the thyroid

In humans, there are typically four glands situated as shown in the illustration; however, the number varies between three and six, with four appearing about 80% of the time. Variations in the positioning of the glands along the craniocaudal axis occur but, excepting parathyroid III which may occasionally be found upon the anterior surface of the trachea, the relation to the posterior surface of the thyroid is rarely lost.

The parathyroid glands are essential for the regulation of calcium and phosphate concentrations in the extracellular fluids of amphibians and higher vertebrates. Parathyroid hormone has two major target organs, bone and kidney. It acts on bone in several ways. Short-term changes include a rapid uptake of bone fluid calcium into osteoblast cells, which in turn pump the calcium into the extracellular fluids. Long-term effects include increased activity and number of osteoclasts, bone cells which act to break down bone matrix and release calcium from bone. All of these effects result in increased blood calcium values. See Bone, Calcium metabolism

Parathyroid hormone inhibits the renal reabsorption of phosphate, thus increasing the urinary output of phosphate. Phosphate reabsorption across the renal tubule is dependent upon sodium transport, and parathyroid hormone interferes with this sodium-dependent phosphate transport in the proximal tubule. Another important effect of parathyroid hormone on the kidney is to increase the renal reabsorption of calcium, thus reducing the loss of calcium in the urine and conserving calcium in the body. See Kidney

Finally, there are reports that parathyroid hormone indirectly stimulates calcium uptake into the body across the intestine. Parathyroid hormone stimulates the production of the most active metabolite of vitamin D, 1,25-dihydroxycholecalciferol, during vitamin D synthesis. This metabolite of vitamin D directly stimulates the intestinal absorption of calcium. See Endocrine system (vertebrate), Parathyroid hormone

parathyroid gland

[¦par·ə′thī‚rȯid ‚gland]
A paired endocrine organ located within, on, or near the thyroid gland in the neck region of all vertebrates except fishes.
References in periodicals archive ?
Others are either asymptomatic or affected by mood disturbances that are not clearly defined; their disease is detected by an incidental finding of hypercalcemia on laboratory studies, which is then followed by an evaluation of intact parathyroid hormone (PTH) levels.
Surgical removal of the parathyroid glands is another cause as is, and more rarely, autoimmune or congenital diseases, according to the FDA.
For the first two rounds of circulation, the parathyroid gland is omitted.
Intact parathyroid hormone (PTH) level was 34 pg/mL (normal, 15-65 pg/mL), serum calcium level was 9.
The preincision parathyroid hormone level was 106 pg/dL.
In populations with chronic kidney disease, low levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, and high levels of intact parathyroid hormone have been suggested to explain the association between chronic kidney disease and cardiovascular mortality.
The first description of the parathyroid glands in human beings was given by Ivar Sandstrom, a medical student in Uppsala, Sweden in 1880.
The topics include assessment and guidelines for primary care referral, cytopathology, the role of nuclear medicine, clinical anatomy and developmental aberrations, an overview of the management of thyroid cancer, and the pathological spectrum and management of parathyroid disease.
His parathyroid hormone level was at the upper half of normal range at 52.
Two surgeons at the University of Arkansas for Medical Sciences recently became the first medical professionals in Arkansas to perform parathyroid surgeries using the da Vinci Surgical System robot.