The parathyroid hormone and its functions in the body
The content of the article:
- Parathyroid glands - what are they?
- Functions of parathyroid hormones
- Parathyroid hormone: normal
-
Disruption of parathyroid hormone production
- Hypoparathyroidism
- Hyperparathyroidism
- Video
The parathyroid glands are small paired formations that are located near the thyroid gland. Both an increase and a decrease in their function are dangerous for a person. The parathyroid hormone affects the exchange of calcium and phosphorus. With an increase in the content of parathyroid hormone in the blood, hyperparathyroidism develops, with a decrease, hypoparathyroidism. Diseases manifest with specific symptoms and require medical or surgical treatment.
Parathyroid glands - four small paired glands that produce parathyroid hormone
Parathyroid glands - what are they?
The parathyroid glands are a paired endocrine organ. Despite their small size (on average, length is 6 mm, width - 4 mm, thickness - 3 mm), they perform an important function - they produce parathyroid hormone and regulate the concentration of calcium in the blood.
There are 4 such glands in the human body. Their name is associated with localization (near the thyroid gland). They are located on the posterior surface of the thyroid gland - two at the upper and lower poles.
Functions of parathyroid hormones
The only hormone of the parathyroid glands is parathyroid hormone (other names are PTH, parathyrin). Its role is to maintain normal blood calcium levels. This is achieved by affecting the function of bone tissue, kidneys and small intestine.
| Target organ | Act |
| Bones |
The main effect of parathyroid hormone is on bone tissue, it activates two groups of cells: osteoclasts and osteoblasts. Initially, parathyroid hormone activates osteoclasts, which are responsible for bone resorption. This flushes calcium out of the bones, which increases its content in the blood. Then there is the activation of osteoblasts, which affect protein synthesis and mineralization processes. Thanks to this, new bone cells are formed. |
| Kidney |
Parathyroid hormone increases the reabsorption of calcium in the kidneys. The result is a decrease in the excretion of calcium in the urine and an increase in its level in the blood. Also, parathyroid hormone affects the metabolism of phosphates - it reduces their reabsorption in the kidneys. This increases the excretion of phosphates in the urine and decreases their concentration in the blood. |
| Intestines |
The action of parathyroid hormone on the intestines is not direct, but indirect. It stimulates the formation of an active metabolite of vitamin D, which increases the absorption of calcium in the small intestine. |
Parathyroid hormone: normal
The normal level of parathyroid hormone depends on the person's age. An analysis for the determination of parathyroid hormone is prescribed if there is a suspicion of a pathology of calcium-phosphorus metabolism. With this test, hyperparathyroidism or hypoparathyroidism can be determined.
| Age | Norm for men and women, pg / ml |
| Under 22 years old | 12–95 |
| 23-70 years old | 9.5-75 |
| Over 70 years old | 4.7-117 |
During pregnancy, the level of parathyroid hormone can range from 9.5 to 75 pg / ml.
Tests are taken in the morning on an empty stomach, regardless of the day of the menstrual cycle.
If the production of parathyroid hormone is impaired, additional research is needed:
- blood biochemistry - determination of the level of calcium and phosphorus, alkaline phosphatase;
- ultrasound - the location, number, size and structure of the parathyroid glands are assessed.
Disruption of parathyroid hormone production
With an increase in the production of parathyroid hormone, hyperparathyroidism develops, with a decrease, hypoparathyroidism. Both conditions are dangerous to human health and life. It is possible to identify pathology using a blood test for hormones. Additionally, a study of the level of electrolytes in the blood and an ultrasound examination will be required.
Hypoparathyroidism
One of the dysfunctions of the parathyroid glands is hypoparathyroidism. With hypoparathyroidism, the function is reduced, there is a lack of parathyroid hormone. The disease is manifested by a violation of calcium-phosphorus metabolism. What happens in the body with hypoparathyroidism:
- Renal phosphate reabsorption is increased.
- The absorption of calcium in the small intestine decreases.
- The reabsorption of calcium in the kidneys decreases, and its excretion in the urine increases.
- The process of bone resorption (resorption) is impaired.
As a result of these changes in the blood, the calcium level decreases (hypocalcemia) and the phosphate level increases (hyperphosphatemia).
How hypoparathyroidism manifests itself clinically:
| Symptom | Explanation |
| Convulsions | The main symptom of hypoparathyroidism is seizures. They arise due to hypocalcemia and increased neuromuscular transmission. At first, twitching of certain muscle groups may appear. Then painful contractions of the muscles of the arms, legs, face develop. |
| Sensory impairment | Convulsions can be accompanied by a change in sensitivity - numbness of the limbs, a feeling of "creeping". |
| Vegetative disorders |
Due to damage to the autonomic nervous system, the following symptoms are observed: • increased sweating; • breathing disorder; • fluctuations in blood pressure; • diarrhea; • increased urine output. |
Treatment of such a disease is medication. Replacement therapy with calcium preparations is prescribed, additionally vitamin D.
Anticonvulsants are given during an attack.
Hyperparathyroidism
Hyperparathyroidism is a disease in which there is an increased concentration of parathyroid hormone in the blood. There are several reasons for this condition, depending on this, the following types of hyperparathyroidism are distinguished:
- Primary - caused by a tumor or hyperplasia of the parathyroid glands.
- Secondary - hyperproduction of parathyroid hormone occurs compensatory against the background of hypocalcemia.
- Tertiary - occurs with the development of adenoma against the background of prolonged hypocalcemia.
Pseudohyperparathyroidism, a condition in which there is an increased production of parathyroid hormone by ectopic tumors, is considered separately.
The clinical signs of hyperparathyroidism include:
| Sign | Explanation |
| Osteoporosis | Parathyroid hormone increases the leaching of calcium from bones. With its excess, the bone tissue becomes more fragile - osteoporosis develops. |
| Kidney damage | Calcium is excreted by the kidneys in the urine. With its excess, stones form in the kidneys - nephrolithiasis develops. |
| Dyspeptic symptoms | Gastrointestinal disorders are observed: nausea, vomiting, a tendency to constipation, flatulence, abdominal pain, weight loss. |
| Heart failure | With damage to the cardiovascular system, myocardial hypotension and arrhythmias develop. Blood pressure may rise. |
The main treatment for hyperparathyroidism is parathyroidectomy. The method consists in the surgical removal of the parathyroid glands.
Video
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Anna Aksenova Medical journalist About the author
Education: 2004-2007 "First Kiev Medical College" specialty "Laboratory Diagnostics".
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