Hyperparathyroidism

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Hyperparathyroidism
Definition
Hyperparathyroidism is a disorder in which too much parathyroid hormone (PTH) is secreted from the parathyroid glands, resulting in abnormally high levels of calcium in the blood (hypercalcemia). Hyperparathyroidism is further classified as being primary, secondary, and tertiary.
Primary hyperparathyroidism is more common than either secondary or tertiary hyperparathyroidism, which occurs in patients with kidney failure or a severe vitamin D deficient state. The parathyroid glands are four pea-sized glands located next to the thyroid gland in the neck; they secrete PTH, which regulates the level of calcium in the blood.
Thyroid and Parathyroid Glands: Posterior (Back) View

Causes
In most cases of hyperparathyroidism, the exact cause is not known. Factors that may contribute to hyperparathyroidism include the following:
• An adenoma (benign tumor) in the parathyroid gland (accounting for 85% of primary hyperparathyroidism)
• Hyperplasia (enlargement) of the parathyroid glands (accounting for over 80% of secondary or tertiary hyperparathyroidism)
• Parathyroid cancer
• Familial hyperparathyroidism
• Vitamin D deficiency (due to malabsorption, lack of sunlight exposure, inadequate dietary intake)
• Radiation therapy to head or neck during childhood
• Multiple endocrine neoplasia (MEN)
• Kidney failure or other medical problems that make the body resistant to the action of the parathyroid hormone (called secondary hyperparathyroidism)
Risk Factors
The following factors increase your chance of developing hyperparathyroidism. If you have any of these risk factors, tell your doctor:
• Sex: female (Hyperparathyroidism is three times more common in women, especially after menopause.)
• Age: older than 60 years
• Multiple endocrine neoplasia (an inherited disorder that affects the endocrine glands)
• Genetics that make you more likely to have hyperparathyroidism
Symptoms
If you experience any of these symptoms, do not assume it is due to hyperparathyroidism. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician.
The degree of hypercalcemia, as well as how rapidly the disease progresses, will determine both the type and severity of the symptoms. Symptoms commonly seen with primary hyperparathyroidism include the following:
• Loss of appetite
• Thirst
• Frequent and sometimes painful urination
• Lethargy
• Fatigue
• Muscle weakness
• Joint pain
• Constipation
• Nausea
• Vomiting
• Abdominal pain
• Memory loss
• Depression
• Heartburn
• Back pain
Symptoms and clinical signs common to those patients with secondary or tertiary hyperparathyroidism include the following:
• Bone pain
• Fracture
• Muscle weakness
• Symptoms related to kidney failure or intestinal diseases such as malabsorption
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam. You may be referred to a doctor who specializes in hormone disorders (endocrinologist) or a surgeon who specializes in endocrine surgery.
Tests may include the following:
• Blood Tests – to measure calcium, phosphorus, alkaline phosphatase, vitamin D, and/or PTH
• Urine Test – to measure calcium excretion and kidney function
• Abdominal X-ray – a test that uses radiation to take a picture of the structures inside the body. This test can show kidney stones caused by high calcium levels
• Bone Density Test – a test to measure bone loss and risk of fractures
• Neck Ultrasound – a test that uses sound waves to examine the body. This test is used to detect a large parathyroid tumor (adenoma).
• Magnetic Resonance Imaging (MRI) – a test that uses magnetic waves to make pictures of structures inside the body. These scans are used to locate a single parathyroid adenoma.
Treatment
Talk with your doctor about the best treatment plan for you. Treatment options include the following:
Medications
• Calcitriol – (the most active vitamin D metabolite) helps to reduce PTH production in secondary hyperparathyroidism in chronic kidney failure
• Cinacalcet – helps to lower PTH blood levels for secondary and tertiary hyperparathyroidism in chronic kidney disease
• Paricalcitol (a vitamin D analog) – for the prevention and treatment of secondary hyperparathyroidism associated with chronic kidney failure
• Ergocalciferol (a vitamin D analog) – for treating secondary hyperparathyroidism due to deficiency of vitamin D
Surgery
Surgical (partial or complete) removal of the parathyroid adenoma in primary hyperparathyroidism or pararthyroid gland tissue in secondary or tertiary hyperparathyroidism is a very effective treatment. This procedure is called partial or complete parathyroidectomy.
In primary hyperparathyroidism, parathyroidectomy results in a 95% cure rate with normalization of serum calcium and increase in bone density with reduced risk of kidney stones. In secondary hyperparathyroidism due to chronic renal failure, parathyroidectomy is often performed in those patients who fail medical treatment.
Monitoring of Blood Calcium Levels
If the hyperparathyroidism is not causing symptoms, your doctor may choose to regularly check your blood calcium levels and monitor you for possible complications of hyperparathyroidism. This may include regular bone density tests.
Prevention
There are no guidelines for preventing hyperparathyroidism.