Despite the hypocalcemia, soft tissue calcifications may develop in patients with hypoparathyroidism when elevated serum phosphorus levels lead to an elevated (i.e., >70 mg2/dL2) calcium × phosphorus solubility product. A patient with poorly controlled, long-standing hypoparathyroidism may develop calcifications in the lens (cataracts) that opacify the lens and can impair vision. Calcifications may also develop in the basal ganglia and, if they are extensive, cause a movement disorder with features of Parkinson disease. These calcifications can be seen on standard radiographs of the skull or on computed tomography, which is a more sensitive technique.
The condition of the teeth provides a clue to the patient’s age at onset of the disease. Dental hypoplasia with poor dental root formation indicates that the disease occurred before age 6. If onset was during childhood, there is crumbling of the teeth because of poor enamel structure. An increased density of the lamina dura can also be seen on dental radiographs.
In patients with hypoparathyroidism, the skeleton is usually not demineralized; in most cases, bone density is normal or slightly increased.
Hypoparathyroidism can occur as part of a familial tendency to the development of autoimmune destruction of multiple endocrine glands. The type 1 polyendocrinopathy syndrome that produces hypoparathyroidism is due to mutations in the AIRE gene that encodes an immune regulatory protein (see earlier), and affected patients often manifest a defect in cell-mediated immunity and an absence of delayed cutaneous hypersensitivity reactions to Candida. Affected patients may have chronic Candida infections of the skin, especially the hands, toes, and nails, as well as infections of the oral mucosa and vagina, but systemic candidiasis is not a feature of this syndrome. Occasionally, these lesions respond to long-term antifungal therapy. Affected patients present initially with chronic fungal infections with subsequent development of hypoparathyroidism and Addison disease. Individuals have an increased incidence of autoimmune primary hypothyroidism, diabetes mellitus, and primary hypogonadism. Alopecia, vitiligo, hepatitis, and pernicious anemia also occur with increased frequency.
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