Secondary hyperparathyroidism is a condition where all the parathyroid glands becoming enlarged and overactive due to another (primary) disease or factor such as kidney failure or vitamin D deficiency.
The parathyroid glands control the calcium level in the bloodstream by secreting parathyroid hormone, or PTH. Low calcium levels in the bloodstream as well as other factors such as elevated phosphorus levels can give rise to overactive parathyroid glands. Kidney failure is the most common cause of secondary hyperparathyroidism and most patients are on dialysis for some time before they are considered candidates parathyroid surgery.
Some of the other less common causes of secondary hyperparathyroidism are:
- Calcium deficiency (from inadequate calcium in the diet or excessive calcium loss in the urine)
- Conditions that make it hard for the body to break down phosphate
- Kidney failure
- Aluminum poisoning
- Certain varieties of cancer
- Malabsorption in the gut
- Vitamin D disorders (commonly seen in people with inadequate sunlight exposure or children with malnutrition):
- Problems absorbing vitamin D (malabsorption)
- Problems breaking down vitamin D (usually due to the use of certain medications)
- Inadequate Vitamin D
- Bone pain
- Fractures (broken bones)
- Itching (pruritis)
Signs and tests
Blood tests check calcium, phosphorus, PTH and sometimes vitamin D levels. A urine calcium level may also be checked. Phosphorus levels may be low with absorption problems, and high in kidney failure. Bone x-rays can detect fractures, and a bone density test can detect bone mineral loss.
Correcting the calcium level, other electrolyte abnormalities and the primary cause of secondary hyperparathyroidism can remove the stimulus for the parathyroid glands to grow and thereby bring the PTH levels back to normal. Treatment may involve vitamin D intake, particularly when lack of intake or poor absorption are the cause.
Patients who have kidney failure and are on dialysis are often given calcium and told to avoid phosphate intake. Vitamin D therapy is also often utilized. Cinacalcet (trade name Sensipar) is often given to control the elevated PTH levels and can be used to prevent the need for an operation. Dialysis is necessary for patients with complete kidney failure. Kidney transplantation may reverse the condition. Surgery to remove the overactive parathyroid glands is often the best course of treatment.
Prognosis or Course of disease
If left untreated secondary hyperparathyroidism can be debilitating or even life threatening. Most patients can be treated with the various measures listed above and their disease controlled. Ultimately, the primary disease determines the prognosis.
Proper vitamin D intake and adequate sunlight exposure may help to prevent secondary hyperparathyroidism. Prevention of kidney failure and proper care once kidney failure have occurred are the mainstay of preventing or controlling secondary hyperparathyroidism.
This is a condition in which secondary hyperparathyroidism is present for an extended period of time and has become unresponsive to treatments including kidney transplant. Treatment is generally the same with patients often benefitting from parathyroid surgery.