Hypoparathyroidism: An Overview

Hypoparathyroidism occurs when one or more of the body’s four parathyroid glands is underactive.¹ These glands, each about the size of a grain of rice, are in the neck next to the thyroid gland and are responsible for regulating calcium, magnesium, and phosphorous in the bloodstream, as well as synthesizing vitamin D.¹ When underactive, not enough parathyroid hormone (PTH) is produced, leading to inadequate calcium and an overabundance of phosphorous in the blood.¹

The condition differs from hypothyroidism, which is when the thyroid gland does not produce enough thyroid hormone,² and hyperparathyroidism, which occurs when the parathyroid glands create high amounts of parathyroid hormone in the bloodstream.³

Considered a rare but treatable condition, hypoparathyroidism is estimated to affect 37 out of every 100,000 people in the United States, and is more prevalent in women than men.⁴

When calcium levels have fallen (hypocalcemia) and phosphorus levels rise, the following symptoms may present:⁵

• tingling in the fingertips, toes, and lips

• muscle cramps, especially in the legs and feet

• muscle pain

• abdominal cramps

• fatigue

• coarse hair that breaks easily or falls out

• irritability, anxiety, or depression

• dry or rough skin

• fingernails that break easily

• abnormal heart rhythm

• brain fog or confusion

• cataracts

• weakened tooth enamel in children

Hypoparathyroidism can be divided into two types:⁴

• primary – due to gland defects (often genetic)

• secondary – impaired or destroyed gland function (usually due to a neck or thyroid injury or surgery)

Adults are more likely to develop hypoparathyroidism from secondary causes, and approximately 75% of cases are due to damage. Symptoms may onset years or even decades after an accident, although indications tend to appear faster following surgery.⁶ Sometimes, these effects can be temporary, and parathyroid function will return to normal. For patients who experience chronic symptoms, treatment will be required.⁶

Children are more likely to develop primary hypoparathyroidism, sometimes called DiGeorge syndrome.⁶ With this syndrome, a child is born without parathyroid glands and is therefore unable to make PTH. Approximately 60% of children with hypoparathyroidism have this syndrome.⁶ Other genetic syndrome involving deafness and kidney disease has also been associated with hypothyroidism.⁶

Other potential causes of hypoparathyroidism include:⁶

• certain autoimmune diseases, particularly polyglandular syndrome

• Addison’s disease

• pernicious anemia

• infiltrative disorders, in which parathyroid glands are invaded by iron or copper

• cancer metastases

Low levels of magnesium can also be a factor since parathyroid glands need the mineral to function properly. This occurrence is considered functional hypoparathyroidism, as the condition tends to resolve when magnesium levels are better regulated.⁶

Diagnosis A blood test that determines levels of PTH, calcium, and phosphorous can lead to diagnosis of hypoparathyroidism.⁵ Specifically, if low levels of PTH and calcium are detected at least twice within 6 months, chronic hypoparathyroidism is likely.⁶

Depending on symptom presentation, an electrocardiogram may check for abnormal heart rhythm, while a CT scan may check for calcium deposits in the brain.⁶

Low amounts of calcium in the body can have significant effects; calcium is involved in nerve regulation, blood clotting, heart function, and muscle contraction.⁶ Not enough of the mineral can affect the body’s ability to maintain these functions, and may also affect bone density since calcium is an essential component of bone health.⁶

Because calcium and phosphorous are electrolytes, which carry an electric charge and help regulate chemical reactions, as well as maintain fluids inside and outside the cells,⁷ hypoparathyroidism can lead to electrolyte imbalance.⁶

The condition has also been associated with an increased risk of renal insufficiency, kidney stones, and cataracts in adults.⁴ For children, complications may include dental issues, slow intellectual development, and poor growth.⁶

Treatment should focus on bringing levels PTH, calcium, and phosphorus levels back into normal ranges, utilizing supplements – often indefinitely. Clinicians often prescribe calcium carbonate and vitamin D, along with regular blood level monitoring. Along with supplements, a diet high in calcium and low in phosphorous is often recommended. In some cases, if supplements fail to achieve normal levels, or muscle spasms become problematic, calcium infusions may be considered.⁵

If hypoparathyroidism remains refractory, parathyroid hormone injections may be considered.⁶ However, long-term use of these injections increase the risk of osteosarcoma.⁶

Overall, regular monitoring is crucial.

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