Definition

Hypoparathyroidism is a condition where the body produces insufficient amounts of parathyroid hormone (PTH). There are four small parathyroid glands located behind the thyroid gland in the neck. PTH plays a critical role in regulating and maintaining the balance of calcium and phosphate in the body. When PTH production is low, blood calcium levels decrease, and phosphate levels increase. These minerals are vital for several functions:

• Calcium. Stored in bones and teeth, calcium contributes to their density and strength. It is also essential for muscle, nerve, and brain function, and plays a role in regulating heart rhythm and blood pressure.
• Phosphate. Found in all cells, phosphate is most abundant in bones and aids in generating energy from food. It is also important for muscle, nerve, heart, and kidney function.

Causes

The causes of hypoparathyroidism may include:

• Neck surgery. The most common cause, hypoparathyroidism can result from accidental damage to the parathyroid glands or removal of the thyroid gland during surgery, often performed to treat thyroid conditions or cancers in the throat or neck.
• Autoimmune diseases. In some cases, the immune system mistakenly attacks the parathyroid glands, causing damage that prevents PTH production.
• Hereditary hypoparathyroidism. Some individuals may be born without functioning parathyroid glands, or with glands that do not function properly. Certain hereditary forms are linked to disorders of other glands.
• Low blood magnesium levels. Magnesium is necessary for normal PTH production, and low levels can impair parathyroid gland function.
• Extensive radiation therapy for cancers of the face or neck. Radiation can damage the parathyroid glands, and in rare cases, radioactive iodine therapy for hyperthyroidism may also result in hypoparathyroidism.

Risk Factor

Several factors can increase the likelihood of developing hypoparathyroidism, including:

• Recent neck surgery, particularly involving the thyroid gland.
• A family history of hypoparathyroidism.
• The presence of certain autoimmune or endocrine diseases, which may reduce hormone production in the affected glands.

Symptoms

The symptoms of hypoparathyroidism are generally associated with low calcium levels in the blood. Common signs and symptoms may include:

• A tingling or burning sensation in the fingertips, toes, and lips.
• Muscle pain or cramping, particularly in the legs, feet, abdomen, or face.
• Muscle twitching or stiffness, especially around the mouth, but also in the hands, arms, and throat.
• Fatigue or weakness.

Additional symptoms linked to hypoparathyroidism may involve:

• Painful menstrual periods.
• Hair loss, resulting in bald patches.
• Dry, rough skin.
• Brittle nails.
• Depression or anxiety.

Diagnosis

To diagnose hypoparathyroidism, your doctor will review your medical history, perform a physical examination, and may order blood and urine tests. Blood test results suggestive of hypoparathyroidism may include:

• Low blood calcium
• Low parathyroid hormone
• High blood phosphate

A magnesium test may also be performed, as low magnesium levels can lead to low calcium levels. Parathyroid hormone normally prevents excess calcium loss through the urine, so a urine test can determine whether your body is excreting too much calcium. Additional tests, such as blood tests or heart rhythm evaluations (echocardiogram or ultrasound), may also be recommended by your physician.

Management

The aim of treatment is to alleviate symptoms and restore normal calcium and phosphate levels in the body.

Common treatment approaches include:

• Oral calcium supplements. These can raise blood calcium levels and are available in various forms, such as tablets, chewables, or liquids. However, high doses may cause digestive side effects, such as constipation.
• Vitamin D. Typically given in high doses as calcitriol, a form of vitamin D that helps the body absorb calcium and excrete phosphate.
• Magnesium supplements. If magnesium levels are low and symptoms of hypoparathyroidism are present, magnesium supplements may be prescribed.
• Thiazide diuretics. These may help reduce urinary calcium excretion if blood calcium remains low despite treatment, or if urinary calcium levels are excessively high.

Complications

Hypoparathyroidism can lead to both reversible and irreversible complications. Reversible complications caused by low calcium levels that may improve with treatment include:

• Prolonged stiffness and cramping in the hands and fingers.
• Muscle pain, twitching, or stiffness in the face, throat, or arms, with throat stiffness posing a potential breathing risk.
• A tingling or burning sensation in the lips, tongue, fingers, and toes.
• Seizures.
• Impaired kidney function, leading to conditions like kidney stones or kidney failure.
• Abnormal heart rhythms (arrhythmias), fainting, and potentially heart failure.

Irreversible complications can include:

• Excessive bone density, potentially resulting in deformities or growth problems.
• Delayed mental development in children.
• Calcium deposits in the brain, which can lead to balance or movement difficulties and seizures.
• Cataracts, causing blurred vision.
• Tooth formation issues, particularly affecting enamel and roots, which may occur if hypoparathyroidism begins early in life.

Prevention

There is no specific way to prevent hypoparathyroidism. However, if you're planning to undergo thyroid or neck surgery, discuss the risks of potential damage to your parathyroid glands with your doctor. Pre-surgery testing of calcium, parathyroid hormone, and vitamin D levels may be recommended, and supplements may be given if necessary.

Parathyroid autotransplantation is an option that might reduce the risk of postoperative hypoparathyroidism. In this procedure, your doctor will attempt to preserve the parathyroid tissue in your neck. If that's not feasible, the parathyroid tissue might be transplanted to another part of your body, such as an arm or chest muscle, although this transplanted tissue may not always function properly.

If you have had surgery or radiation therapy involving your thyroid or neck, be alert to symptoms that may suggest hypoparathyroidism, such as tingling or burning sensations in your fingers, toes, or lips, and muscle twitching or cramping. Early treatment with calcium and vitamin D may be recommended to mitigate the condition's effects.

When to See a Doctor?

If you experience symptoms associated with hypoparathyroidism, consult a doctor for evaluation. Seek immediate medical attention if you experience seizures or difficulty breathing, as these may indicate serious complications of the condition.

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