This depletes the ECF ionized calcium and increases the urinary calcium concentration. In the absence of PTH, bone resorption, phosphaturic effect, renal distal tubular calcium reabsorption, and 1,25-dihydroxy vitamin D mediated dietary calcium absorption cannot occur. Therefore, the consequence of PTH deficiency is hypocalcemia. Hypoparathyroidism results in hypocalcemia, which may be variably symptomatic. Muscle cramps involving the lower back, legs, and feet are common in patients with hypoparathyroidism and hypocalcemia.
Tetany develops if hypocalcemia is severe.
In some patients, laryngospasm and bronchospasm may be life threatening. Hypocalcemia of primary hypoparathyroidism may cause extrapyramidal choreoathetoid syndromes in patients with basal ganglia calcifications. Spastic paraplegia, ataxia, dysphagia, and dysarthria have been documented in association with hypoparathyroidism-induced hypocalcemia. Severe hypocalcemia causes papilledema, which improves with treatment of the calcium derangement. Emotional instability, anxiety, depression, confusion, hallucinations, and psychosis have been described in patients with hypoparathyroidism when the calcium level is low.