The condition results from a decreased or absent secretion of one of four small parathyroid glands located on the back of the lower edge of the thyroid gland, or set within it. These glands secrete parathyroid hormone (parathormone). Parathormone (PTH) is one of the hormones involved in the regulation of calcium and phosphorous levels.

Hypoparathyroidism is decreased function of the parathyroid glands, leading to decreased levels of parathyroid hormone (PTH). The consequence is an abnormally low level of calcium in the blood (hypocalcemia), a serious medical condition.

The condition may result from removal of the parathyroid glands or destruction of the glands as may be seen following neck surgery (thyroid surgery or cancer involving the neck). In addition, genetic-related causes include failure of the glands to develop and mutations in the parathormone gene that prevent synthesis and secretion of the hormones. There can also be intermittent deficiencies caused by low magnesium levels and pseudohypoparathyroidism caused most frequently by organ resistance to PTH. Resistance to PTH action can occur with chronic renal failure, and magnesium and Vitamin D deficiencies.

There is increased neuromuscular excitability resulting in convulsions and tetany, wheezing, muscle cramps, polyuria, mood changes, and exhaustion. Serum calcium levels fall and phosphorus levels rise. Other symptoms include: blurring of vision secondary to cataracts, poorly formed teeth when the condition begins in childhood, a defect in the development of hair and nails, and dry, scaly skin.

Diagnosis is established when there is a low or unrecognizable blood parathyroid (PTH) level along with low calcium levels, high phosphorous levels, and normal renal function. In addition, antibodies have been found in the autoimmune type of the disease.

The goal of treatment is to obtain and maintain the lowest serum calcium concentration compatible with the avoidance of symptoms. Transient forms of hypoparathyroidism usually do not require treatment. Reversible forms should be treated as needed, e.g., low magnesium levels are corrected with magnesium replacements. In addition, lifelong treatment with oral Vitamin D is required for patients with pseudohypoparathyroidism.

All forms of hypoparathyroidism are considered rare. After treatment, serum and urine calcium levels must continue to be monitored. Chronic hypocalcemic conditions may be associated with presence of subcapsular cataracts, changes in the skin and nails, papilledema, intracranial calcifications, and parkinsonian-like movement disorder.

•  Consider service connection on a presumptive basis as a chronic condition (38 CFR §3.307; §3.309 (a)).  

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