Causes

The differential diagnosis of hypoparathyroidism includes:

(1) idiopathic hypoparathyroidism, in which the parathyroids are absent or atrophied. This condition occurs sporadically or in association with genetic autoimmune syndromes or DiGeorge syndrome.

(2) pseudohypoparathyroidism, in which bone and kidney tissue are unresponsive to parathyroid hormone (PTH)

(3) damage or accidental removal of parathyroid glands during thyroidectomy. Transient hypoparathyroidism and hypocalcemia from subtotal thyroidectomy are common,55,56 but permanent hypoparathyroidism is a rare complication of thyroid surgery.

Clinical presentation

Seizures occur in up to 70% of patients with symptomatic hypoparathyroidism.3,41,57

Parkinsonism, dystonia, hemiballismus, choreoathetosis, and oculogyric crises occur in 5–10% of patients with idiopathic hypoparathyroidism,58 but are less common in patients with surgical hypoparathyroidism or other causes of hypocalcemia.59 Other neurologic findings may include spastic paraplegia, ataxia, dysarthria, and dysphagia.

Chronic hypocalcemia in patients with hypoparathyroidism may be associated with dry, puffy, or coarse skin; dental changes (if hypocalcemia is present during early development60,61); and cataracts.

Evaluation

PTH levels are low or undetectable in patients with hypoparathyroidism.

In pseudohypoparathyroidism, patients have hypocalcemia. Most have high serum PTH and phosphate concentrations and low serum calcitriol concentrations. Brain CT scans may show basal ganglia calcification, particularly in chronic cases.62,63

Treatment

The acute management of symptomatic hypoparathyroidism involves correction of hypocalcemia and other associated electrolyte abnormalities.

Adapted from: Schachter SC and Lopez MR. Metabolic disorders. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;195–208.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised April 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.