Parathyroid hormone

The parathyroid glands control the level of calcium in the blood and bones. This article discusses the proper functioning of the parathyroid glands, the properties and effects of parathyroid hormone, how the parathyroid glands monitor and control blood calcium levels, and how it affects your health!

 

Parathyroid hormone and calcium concentration

PTH, also known as parathyroid hormone. It is produced by the parathyroid glands. These are four pea-sized glands in your neck. Parathyroid hormone controls the level of calcium in the blood. Calcium is a mineral that keeps bones and teeth healthy and strong. It is also essential for the proper functioning of the nerves, muscles and heart.

If blood calcium levels are too low, the parathyroid glands release PTH into the blood. This causes an increase in calcium levels. If blood calcium levels are too high, these glands will stop producing PTH. Too high or too low levels of PTH can cause serious health problems. In both cases, we will have hypoparathyroidism or hyperparathyroidism. However, parathyroid hormone pth can regulate this.

It does this through its effects on the kidneys, bones and intestines:

Bones – parathyroid hormone pth stimulates the release of calcium from the large stores found in the bones into the bloodstream. This increases bone destruction and reduces the formation of new tissue.

Kidneys – parathyroid hormone pth reduces urinary calcium loss. Parathyroid hormone also stimulates the production of active vitamin D in the kidneys.

Intestines – parathyroid hormone indirectly increases the absorption of calcium from food in the intestine by affecting the metabolism of vitamin D.

 

How is parathyroid hormone controlled?

Parathyroid hormone is mainly controlled by the negative feedback of calcium levels in the blood to the parathyroid glands. Low blood calcium levels stimulate the release of parathyroid hormone, while high blood calcium levels prevent the release of parathyroid hormone.

Although the four parathyroid glands are quite small, they have a very rich blood supply. This suits them because they need to monitor their blood calcium levels 24 hours a day. As the blood filters the parathyroid glands, they detect the amount of calcium present in the blood and respond by producing more or less Parathyroid hormone. When blood calcium levels are too low, the parathyroid cells sense this and produce more parathyroid hormone. Once parathyroid hormone is released into the blood, it circulates throughout the body to work in many places and to increase the amount of calcium in the blood (by removing calcium from the bones). When the level of calcium in the blood is too high, the parathyroid cells produce less parathyroid hormone (or stop producing it altogether), allowing calcium levels to fall. This feedback mechanism works constantly, thus keeping calcium and parathyroid hormone in ”normal” concentration. In a healthy person with normal parathyroid glands, their glands will switch on and off dozens of times a day trying to keep their calcium levels within the normal range to keep our brains and muscles working properly.

Any person with normal parathyroid function will have a constant calcium level with almost zero variability. For example, if your calcium level this week is 9.6 and you have healthy parathyroid glands, then your calcium level will be between 9.4 and 9.8 every time you measure it for most of your life.

If a person has a disorder of the parathyroid glands, they have lost their regulatory system and the calcium levels in these patients range from high to low.

Let us remember that hypoparathyroidism and hyperparathyroidism can lead to a number of health problems and increase calcium absorption and negative impact on our skeletal system.

 

How does parathyroid hormone increase blood calcium levels?

Like all endocrine glands, the parathyroid glands produce a hormone (a small a protein capable of causing a specific response from distant cells in the body). Parathyroid hormone pth has a very strong effect on bone cells, causing them to release calcium into the bloodstream. Calcium is the main structural component of bones that gives them rigidity – but keep in mind that the main purpose of bones is to provide a calcium storage system – so our brain will never be deprived of calcium. In the presence of parathyroid hormone, the bones will give up calcium in an attempt to increase blood calcium levels. Under normal circumstances, this process is very fine-tuned and the amount of calcium in our bones remains at a normal, high level. However, in the presence of too much parathyroid hormone, the bones will continue to release calcium into the blood at too high a rate, causing the bones to have too little calcium. This condition is called osteopenia and osteoporosis, which causes the bone to develop more “pores” (or holes) and less bone mass. When bones are exposed to high levels of parathyroid hormone for several years, they become brittle and much more likely to break. Another way parathyroid hormone works to increase blood calcium levels is through its effect on the intestines. In the presence of parathyroid hormone, the intestinal lining absorbs the calcium normally found in our diet more effectively.

 

Hyperparathyroidism and hyperparathyroidism

The main problem in the parathyroid glands is the production of too much parathyroid hormone , causes high levels of calcium in the blood (hypercalcaemia) and this is known as primary hyperparathyroidism. There is a similar but much rarer condition called tertiary hyperparathyroidism, which causes hypercalcemia due to excessive production of parathyroid hormone in the back of all four glands, which is overactive. Secondary hyperparathyroidism occurs in response to low blood calcium levels and is caused by other mechanisms, such as kidney disease and vitamin D deficiency.

Mild primary hyperparathyroidism often causes minor (if any) symptoms and is often diagnosed by finding high levels of calcium on a routine blood test. Treatment may include surgical removal of the defective glands (parathyroidectomy).

Too little parathyroid hormone or hypoparathyroidism is a rare condition. May cause low levels of calcium in the blood (hypocalcaemia). It is usually treated medically with oral calcium and vitamin D analogues, but the availability of parathyroid hormone replacement therapy may change the treatment approach for some patients.

 

PTH test and elevated calcium

The PTH test is most commonly used with the calcium test to:
 

• Diagnosed with hyperparathyroidism - a condition in which the parathyroid glands produce too much parathyroid hormone
• Diagnosed with hypoparathyroidism - a condition in which the parathyroid glands produce too little parathyroid hormone
• Check if abnormal calcium levels are due to a problem with the parathyroid glands
• Kidney disease monitoring

You may need a PTH test if your results were not normal in the previous calcium test. You may also need this test if you have symptoms of too much or too little calcium in your blood.

Symptoms of too much calcium include:

• Bones that break easily
• More urination
• Increased Desire
• Nausea and vomiting
• Fatigue
• Kidney stones