Definition
Hyperparathyroidism is a disease of the parathyroid gland with increased production and release of parathyroid hormone (PTH).
FormsCauses
Hyperparathyroidism is distinguished into:
- Primary hyperparathyroidism
- Secondary hyperparathyroidism
- Tertriary hyperparathyroidism
Primary hyperparathyroidism
In principle, two types of hyperparathyroidism (parathyroid hyperthyroidism) can be distinguished: primary parathyroid hyperthyroidism is caused by a disease of the cells of the parathyroid gland (epithelial bodies). The cause is usually the parathyroid gland. In 15% of cases, the cause of primary parathyroid hyperfunction is a so-called hyperplasia of the epithelial bodies. In only 1%, a carcinoma of the parathyroid gland can trigger primary parathyroid hyperfunction.
- Solitary (single) adenomas (80% of cases) or
- Multiple (increased) adenomas (5% of cases)
Secondary hyperparathyroidism
The second form of hyperparathyroidism (hyperparathyroidism) is the secondary variant. In this case, a regulatory release of parathyroid hormone occurs in healthy parathyroid glands and other underlying diseases. In principle, it can be stated that whenever the body’s calcium level falls below a certain limit, the parathyroid gland releases the parathyroid hormone, which then makes calcium available to the body again via appropriate mechanisms.
The causes of a reduced calcium level, which is responded to by an increased release of parathyroid hormone, are of very different nature. For example, diseases of the kidney can be responsible for increased calcium excretion in the urine, thus lowering the calcium level unnaturally low. A reduced calcium intake from food, the so-called malabsorption syndrome, can also trigger a reduced calcium level in the body and thus lead to secondary parathyroid hyperactivity. In rare cases, liver cirrhosis can also lead to this clinical picture due to disturbed calcium processing. Nowadays only very rarely seen is hyperparathyroidism due to reduced solar radiation (also leads to an incorrect calcium utilization).
Tertiary parathyroid hyperfunction
This is called tertiary hyperparathyroidism (overactive parathyroid gland), when a secondary form of the disease with increased release of parathyroid hormones results in an excessive calcium level in the blood (hypercalcaemia). The cause of this parathyroid hyperthyroidism is an imbalance between the amount of parathyroid hormone and the calcium requirement. If an increased amount of calcium is made available by increased parathyroid hormone release, this occurs through various mechanisms: so-called osteoclasts break down more calcium stored in the bones. The absorption of the calcium in food is increased and there is an increased reabsorption of calcium in the kidney.
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