Hypoparathyroidism is is an endocrine disorder in which the parathyroid glands in the neck do not produce enough parathyroid hormone (PTH). PTH plays a key role in regulating and maintaining a balance of your body's minerals, namely calcium and phosphorus.
The low production of PTH in hypoparathyroidism leads to abnormally low ionized calcium levels in your blood and bones and to an increase of serum phosphorus. Current treatment consists of taking supplements to normalize your calcium and phosphorus levels.
Signs and symptoms of hypoparathyroidism can include:
- Tingling or burning (paresthesias) in your fingertips, toes and lips
- Muscle aches or cramps affecting your legs, feet, abdomen or face
- Twitching or spasms of your muscles, particularly around your mouth, but also in your hands, arms and throat
- Fatigue or weakness
- Painful menstruation
- Patchy hair loss, such as thinning of your eyebrows
- Dry, coarse skin
- Brittle nails
- Depression, mood swings
- Memory problems
Hypoparathyroidism occurs when your parathyroid glands don't secrete enough parathyroid hormone. You have four parathyroid glands — each normally about the size of a grain of rice — situated in your neck, adjacent to your thyroid gland.
The low production of PTH leads to abnormally low calcium levels (hypocalcemia) in your blood and bones and to increased levels of serum phosphorus (hyperphosphatemia).
Factors that can cause hypoparathyroidism include:
- Acquired hypoparathyroidism. This most common cause of hypoparathyroidism develops after accidental damage to or removal of the parathyroid glands during surgery. This surgery may be a treatment for diseases of the nearby thyroid gland, or for throat cancer or neck cancer. Today, surgeons are more careful to avoid injuring the parathyroid glands during surgery.
- Autoimmune disease. In this condition, your immune system creates antibodies against the parathyroid tissues, trying to reject them as if they were foreign bodies. In the process, the parathyroid glands stop manufacturing their hormone.
- Hereditary hypoparathyroidism. In this form, either the parathyroid glands aren't present at birth, or they don't work properly. Some types of hereditary hypoparathyroidism are associated with deficiencies of other hormone-producing glands.
- Extensive cancer radiation treatment of your face or neck. Radiation can result in destruction of your parathyroid glands, as can radioactive iodine treatment for hyperthyroidism, occasionally.
- Low levels of magnesium in your blood, which can affect the function of your parathyroid glands. Normal serum magnesium levels are required for optimum secretion of parathyroid hormone.
Calcium and phosphorus are important body minerals. They form the mineral component of bones, and they exist as charged particles called ions in the blood and inside cells. Parathyroid hormone (PTH) regulates the amount of calcium and phosphorus in bone and blood. PTH is made by four small parathyroid glands located in the neck behind the thyroid gland. Hypoparathyroidism occurs when there is too little PTH. Blood calcium levels fall, and phosphorus levels rise. The most common cause of hypoparathyroidism is injury to the parathyroid glands during head and neck surgery. Rarely, hypoparathyroidism is a side effect of radioactive iodine treatment for hyperthyroidism. PTH secretion also may be impaired when blood levels of magnesium are low, or when blood pH is too high, a condition called metabolic alkalosis. DiGeorge syndrome is a childhood disease in which hypoparathyroidism occurs due to a total absence of the parathyroid glands at birth. Familial hypoparathyroidism occurs with other endocrine diseases, such as adrenal insufficiency, in a syndrome called type I polyglandular autoimmune syndrome (PGA I).
There are no specific actions you can take to prevent hypoparathyroidism. However, if you're scheduled to have thyroid or neck surgery, talk to your surgeon for assurance that steps will be taken to avoid damage to your parathyroid glands during the procedure.
If you've had surgery involving your thyroid or neck, be alert for signs and symptoms that could indicate hypoparathyroidism, such as a tingling or burning sensation in your fingers, toes or lips, or muscle twitching or cramping. When they occur, your doctor may recommend prompt treatment with calcium and vitamin D to minimize the effects of the disorder
Factors that may increase your risk of developing hypoparathyroidism include:
- Recent neck surgery, particularly if the thyroid was involved
- A family history of hypoparathyroidism
- Having certain autoimmune or endocrine conditions, such as Addison's disease — a condition characterized by a deficit in hormone production by the adrenal glands
the following findings may indicate hypoparathyroidism:
- A low blood-calcium level
- A low parathyroid hormone level
- A high blood-phosphorus level
- A low blood-magnesium level
Diagnosis is by measurement of calcium, serum albumin (for correction) and PTH in blood. PTH degrades rapidly at ambient temperatures. If necessary, measuring cAMP (cyclic AMP) in the urine after an intravenous dose of PTH can help in the distinction between hypoparathyroidism and other causes. Differential diagnoses are: Pseudohypoparathyroidism (normal PTH levels but tissue insensitivity to the hormone, associated with mental retardation and skeletal deformities) and pseudopseudohypoparathyroidism (sic). Vitamin D deficiency or hereditary insensitivity to this vitamin (X-linked dominant). Malabsorption Kidney disease Medication: steroids, diuretics, some antiepileptics. Other tests include ECG for abnormal heart rhythms, and measurement of blood magnesium levels.
Hypoparathyroidism may result in numerous complications if not treated. The following complications are due to low calcium levels, most of which are likely to improve with adequate treatment:
- Tetany. These cramp-like spasms of your hands and fingers may be prolonged and painful. Tetany may also include muscle discomfort and twitches or spasms of the muscles of your face, throat or arms. When these spasms occur in your throat, they can interfere with breathing, creating a potential emergency.
- Paresthesias. These are characterized by sensory symptoms of odd, tingling sensations or pins and needles feelings in your lips, tongue, fingers and feet.
- Loss of consciousness with convulsions (grand mal seizures).
- Malformation of the teeth, affecting dental enamel and roots.
- Impaired kidney function.
- Heart arrhythmias and fainting, even heart failure.
Accurate diagnosis and effective treatment may prevent these complications associated with hypoparathyroidism, but once present, they won't improve with calcium and vitamin D treatment:
- Stunted growth (short stature)
- Slow mental development (or mental retardation) in children
- Calcium deposits in the brain, which can cause balance problems and seizures
The goal of treatment is to relieve symptoms and to normalize levels of calcium and phosphorus in your body. A treatment regimen typically includes:
- Oral calcium carbonate tablets. Oral calcium supplements can increase calcium levels in your blood. However, at high doses, calcium supplements can cause gastrointestinal side effects, such as constipation, in some people.
- Vitamin D. High doses of vitamin D, generally in the form of calcitriol, can help your body absorb calcium and eliminate phosphorus.
In addition, your doctor may prescribe
- Parathyroid hormone: FDA approved indication as adjunct to calcium and vitamin D to control hypocalcemia in patients with hypoparathyroidism
Your doctor may recommend that you consult a dietitian, who is likely to advise a diet that is:
- Rich in calcium. This includes dairy products, green leafy vegetables, broccoli, kale, and fortified orange juice and breakfast cereals.
- Low in phosphorus-rich items. This means avoiding carbonated soft drinks, which contain phosphorus in the form of phosphoric acid, and limiting eggs and meats.
If you need immediate symptom relief, your doctor may recommend hospitalization to administer calcium by intravenous (IV) infusion. These IV infusions may be important if you're having severe spasms associated with tetany. After hospital discharge, you can continue to take calcium and vitamin D orally.
Tto monitor levels of calcium and phosphorus levels in the blood. Initially, these tests will probably be weekly to monthly. Eventually, you'll need blood tests just twice a year.
Because hypoparathyroidism is a long-lasting (chronic) disorder, treatment generally is lifelong, as are regular blood tests to determine whether calcium in particular is at normal levels. Your doctor will adjust your dose of supplemental calcium if your blood-calcium levels rise or fall.
If calcium in your blood remains low despite treatment, your doctor may add a prescription diuretic medication — specifically a thiazide diuretic such as hydrochlorothiazide or metolazone. While some other types of diuretics (loop diuretics) decrease calcium levels in your bloodstream, the thiazides can increase blood-calcium levels.
Most people who are treated for hypoparathyroidism can keep their symptoms under control if they continue to receive treatment. Early diagnosis and treatment can help prevent complications of hypoparathyroidism, some of which are permanent.