Hypoparathyroidism Tetany

The main features of hypocalcemia are neuromuscular—tetany, paresthesias, laryngospasm, muscle cramps, and convulsions. The major causes of hypocalcemia in the adult are hypoparathyroidism, vitamin D deficiency, chronic kidney disease, and malabsorption. Neonatal hypocalcemia is a common disorder that usually resolves without therapy. The roles of PTH, vitamin D, and calcitonin in the neonatal syndrome are under active investigation. Large infusions of citrated blood can produce hypocalcemia by the formation of citrate-calcium complexes. Calcium and vitamin D (or its metabolites) form the mainstay of treatment of hypocalcemia. 

Kahn A, Snapper I, Drucker A. Corticosteroid-induced tetany in latent hypoparathyroidism. Arch Intern Med 1964 114 434-8. 

Parathyroid hormone (PTH) Primary hyperparathyroidism causes hypercalcemia, hypophosphatemia, and increased urinary cAMP hypoparathyroidism causes hypocalcemia and hyperphosphatemia, often with soft-tissue calcification and tetany and convulsions. Binds to cell-surface receptors and activates adenylate cyclase increases bone mineralization and activity of renal lot-hydroxylase in kidney, reabsorption of Ca " " increases and reabsorption of phosphate decreases. 

Neurologic Chvostek s and/or Trousseau s signs can be elicited during physical examination. The hallmark of acute hypocalcemia is tetany, which is characterized by neuromuscular irritability including seizure potential. Ex-trapyramidal disorders, mainly parkinsonism but also dystonia, hemiballismus, choreoathetosis, and oculogyric crises, occur in 5% to 10% of patients with idiopathic hypoparathyroidism. 

In support of this suggestion, it is known that high phosphate feeding may produce tetany and that low phosphate feeding or Benemid administration may relieve it in hypoparathyroidism (P2). Conversely, Albright (A2) has demonstrated that in primary hyperparathyroidism... 

Excess phosphorus in the blood serum, which may result (1) when the kidneys do not excrete phosphorus adequately, or (2) from hypoparathyroidism, which causes an insufficient secretion of parathyroid hormone. When serum phosphorus rises, serum calcium falls, causing tetany. 

B. Chronic.— Idiopathic hypoparathyroidism ajid some forms of infantilism exemplify the chronic condition. Infantile tetany, which is always associated with rickets, is not regarded sis being a psirathyroid disorder. 

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