Parathyroid hormone
and Eva Rudolf-Müller, doctorValeria Dahm is a freelance writer in the medical department. She studied medicine at the Technical University of Munich. It is particularly important to her to give the curious reader an insight into the exciting subject area of medicine and at the same time to maintain the content.
More about the expertsEva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.
More about the experts All content is checked by medical journalists.Parathyroid hormone (PTH) is an important hormone that is produced in the parathyroid glands. It increases the calcium levels in the blood through various mechanisms and at the same time lowers the phosphate levels. Find out here which diseases can cause parathyroid hormone to be increased or decreased.
What is parathyroid hormone?
Parathyroid hormone is a hormone that consists of 84 amino acids (protein building blocks) and is also called PTH or parathyrin. If the calcium level in the blood drops (hypocalcemia), the so-called main cells of the parathyroid glands produce parathyroid hormone. This primarily reaches the bones via the blood. Here it stimulates the osteoclasts via a complex system. These are special cells that break down bone tissue. Calcium and phosphate are released in the process.
At the same time, parathyroid hormone affects the kidneys and ensures that more phosphate is excreted in the urine and calcium is reabsorbed into the body.
Overall, this means: Parathyroid hormone increases the calcium level and lowers the phosphate level in the blood. The less phosphate there is in the blood, the more calcium can be freely present in the blood, otherwise the two will combine to form a poorly soluble complex. The calcium-phosphate complexes can be deposited in tissues, organs and arteries and lead to circulatory disorders.
Vitamin D3 (calcitriol) is also increasingly synthesized in the kidneys by parathyroid hormone. It increases the absorption of calcium from nutrients in the intestine.
The antagonist of the parathyroid hormone is the hormone calcitonin, which is produced in the thyroid. It has the opposite effect to parathyroid hormone: Calcitonin lowers the calcium level and increases the phosphate level.
When is the parathyroid hormone determined?
The doctor measures the parathyroid hormone level in the blood if he suspects a disruption of the calcium-phosphate balance. In addition, the measured value provides information on diseases of the parathyroid gland such as over- or under-function. The parathyroid hormone value (PTH value) is always determined together with the calcium and phosphate value.
Parathyroid hormone normal values
The parathyroid hormone level in the blood is determined from the serum. Blood is usually taken in the morning from an empty patient. Various enzymes break down the parathyroid hormone quickly, which is why the sample must be processed quickly. In healthy adults, parathyroid hormone levels in the blood are usually 15 to 65 picograms per milliliter (pg / ml). Attention: As with many laboratory values, the exact reference range depends on the method.
When is the parathyroid hormone too low?
As a completely normal reaction of the body, parathyroid hormone is always reduced when the calcium content in the blood is high (hypercalcemia). However, the calcium level can also be increased due to illness, as a result of which the parathyroid hormone remains too low.
This can be the case, for example, with various tumors such as breast cancer (breast cancer) if they lead to bone loss and thus to a release of calcium phosphate. An overactive thyroid gland (hyperthyroidism) and sarcoidosis (a systemic disease) can also cause increased calcium levels, which reduce parathyroid hormone production.
If the parathyroid hormone and calcium are reduced at the same time, the parathyroid gland is underactive (hypoparathyroidism): Although the calcium content is too low, the parathyroid glands are not able to counteract the increased production and release of parathyroid hormone. In most cases, the causes are operations on or in the area of the thyroid gland or autoimmune processes. In the worst case, hypocalcemia leads to seizures and cardiac arrhythmias.
When is the parathyroid hormone too high?
As already mentioned, parathyroid hormone rises physiologically with low calcium (hypocalcemia) in the blood. In some people, however, there is an overactive parathyroid gland, in which too much parathyroid hormone is produced. Then one speaks of hyperparathyroidism.
Usually it is an autonomic overfunction (primary hyperthyroidism). In the majority of cases it is caused by a benign tumor (adenoma) of the parathyroid gland. Another possible cause is an enlargement (hyperplasia) or - less often - a malignant tumor (carcinoma) of the parathyroid gland.
So-called secondary hyperparathyroidism occurs when the parathyroid glands have to synthesize more parathyroid hormone because the calcium in the blood is continuously low. A possible reason is chronic kidney failure or malabsorption (impaired absorption of nutrients such as calcium and vitamin D from food). The secondary hyperparathyroidism is, in contrast to the primary, a reaction to other processes in the body.
Every form of hyperparathyroidism triggers increased bone loss and remodeling. This can be seen on x-rays and often causes bone and joint pain. Other possible symptoms include nausea, nausea, kidney stones and gastrointestinal ulcers.
What to do if the parathyroid hormone is increased or decreased?
The treatment is based on the underlying disease. The reduced calcium values in hypoparathyroidism can be compensated for by ingesting calcium and vitamin D. The treatment of tumors belongs in the hands of experienced oncologists.
In primary hyperparathyroidism, the independently working parts of the parathyroid glands are surgically removed. Therapy for secondary hyperparathyroidism in the context of kidney disease includes, among other things, a balanced fluid intake and strict blood pressure control. In addition, phosphate-rich foods such as nuts should be avoided and vitamin D should also be consumed. The aim is to normalize the parathyroid hormone level in the blood.
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