Hyperparathyroidism is a hormonal disorder caused by the parathyroid glands in the neck producing too much parathyroid hormone (PTH).
The parathyroid glands are four small organs, each about the size of a grain of rice that lie behind the thyroid gland in the neck. Although, the parathyroid glands are located near to the thyroid, the functions of these organs are not related.
The parathyroid glands produce PTH, an essential regulator of calcium, phosphorus and vitamin D levels in the bones and blood. Levels of these substances tend to fluctuate and need to be maintained within a fixed range in order to ensure healthy bodily function. The calcium level can rise after dairy-rich food is ingested or it may fall with the use of certain medications, for example.
What happens in hyperparathyroidism?
As the blood PTH level begins to rise, the blood calcium level also rises, leading to hypercalcemia. At the same time, the blood phosphate level starts to fall, leading to hypophosphatemia.
Symptoms of hyperparathyroidism
Hyperparathyroidism may not present with symptoms. However, if hypercalcemia occurs, some of the symptoms that may develop include depression, fatigue, muscle weakness, nausea, loss of appetite, constipation, abdominal pain, feeling thirsty, frequent urination and lack of concentration. If left untreated, hypercalcemia can become more severe and lead to vomiting, dehydration, confusion, drowsiness, bone pain, muscle spasms, arrhythmia and high blood pressure. Worse still, severe hypercalcemia can even lead to loss of consciousness and coma.
Causes of hyperparathyroidism
Primary hyperparathyroidism – This occurs when one or more of the parathyroid glands becomes overactive and/or enlarged due to a problem within the gland itself.
Secondary hyperparathyroidism – This occurs when another condition such as kidney disease or vitamin D deficiency leads to a low calcium level. The parathyroid gland compensates by producing excess PTH to try and restore the calcium level.
If the secondary hyperparathyroidism remains untreated, the parathyroid remains permanently overactive and this is referred to as tertiary hyperparathyroidism. This condition is often seen in patients with chronic kidney failure.
Diagnosis and treatment
Hyperparathyroidism is diagnosed based on a blood test that reveals a raised PTH level, raised blood calcium level and low phosphate level. X-rays may indicate bone loss, bone fracture or bone softening.
In mild cases, treatment may not be necessary and routine monitoring may be all that is required. In symptomatic individuals, surgical removal of the parathyroid gland may be necessary, which cures hyperparathyroidism in 95% of cases. In cases where surgery is not possible, medications that may be prescribed include bisphosphonates, which improve bone density, and cinacalcet, which lowers the blood calcium and PTH level and increases the phosphate level.
Reviewed by Sally Robertson, BSc