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  • • Paresthesias, muscle cramps, carpopedal spasm, laryngeal stridor, convulsions, malaise, muscle and abdominal cramps, tetany, urinary frequency, lethargy, anxiety, psychoneurosis, depression, and psychosis

    • History of central neck (thyroid, parathyroid, or laryngeal) resection

    • Positive Chvostek and Trousseau signs

    • Brittle and atrophied nails, defective teeth, cataracts

    • Hypocalcemia and hyperphosphatemia, low or absent urinary calcium, low or absent circulating parathyroid hormone (PTH)

    • Calcification of basal ganglia, cartilage, and arteries as seen on x-ray

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Epidemiology

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  • • Although uncommon, occurs most often as a complication of thyroid surgery (especially for malignancy or recurrent goiter)

    • Idiopathic hypoparathyroidism is an autoimmune process and can be associated with autoimmune adrenocortical insufficiency

    • Rare, but possible, after radioiodine therapy for hyperthyroidism

    • Neonatal tetany associated with maternal hyperparathyroidism

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Symptoms and Signs

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  • • Tetany

    • Positive Chvostek or Trousseau signs (or both)

    • Paresthesias, circumoral numbness, muscle cramps, irritability, carpopedal spasm, convulsions, opisthotonos, and marked anxiety

    • Dry skin, brittle nails, spotty alopecia

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Laboratory Findings

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  • • Low serum calcium

    • Elevated serum phosphate

    • Low urinary calcium

    • Low or absent urinary phosphate

    • Low serum PTH

    • Low urine hydroxyproline

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Imaging Findings

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  • • Calcification of the basal ganglia, arteries, and external ear

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  • • Most postoperative hypocalcemia is transient

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Rule Out

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  • • Tetany from hyperventilation and alkalosis

    • Hypocalcemia from remineralization of bones after therapy for hyperparathyroidism ("hungry bones")

    • Hypocalcemia from intestinal malabsorption or renal insufficiency

    • Pseudohypoparathyroidsim (X-linked syndrome with defective renal adenylyl cyclase system; associated with round face, thick body, stubby fingers, mental deficiency, and x-ray evidence of calcifications; may have associated thyroid or ovarian dysfunction; patients do not respond with phosphaturia to PTH challenge; serum concentrations of PTH are increased; can be controlled with low dose vitamin D)

    • Pseudopseudohypoparathyroidism (thought to be common genetic defect as pseudohypoparathyroidism, but more mild; hypocalcemia only brought out during periods of stress such as pregnancy and rapid growth)

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  • • History and physical exam

    • Special note of prior neck surgery

    • Serum and urine tests for calcium, phosphate, and PTH

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When to Admit

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  • • In the presence of acute hypoparathyroid tetany

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  • • Aim of treatment is to raise serum calcium levels, to bring the patient out of tetany (if present), and to lower serum phosphate levels (to prevent metastatic calcification)

    • Treatment is medical (unless parathyroid tissue was cryopreserved at the time of neck operation)

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Medications

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  • • Oral calcium (calcium, lactate, or carbonate)

    • Calcitriol

    • IV calcium gluconate for acute tetany (6 g mixed in 500 mL DSW infused at 1 mL/kg/h)

    • Magnesium sulfate if also hypomagnesemic

    • Phosphorous limited diet, and possibly phosphate binders such as aluminum hydroxide gel

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Treatment Monitoring

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  • • Symptomatic monitoring

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