TABLE 100.10 CAUSES OF HYPOCALCEMIA Precipitation or altered binding Hyperphosphatemia Metabolic alkalosis Citrated products Pancreatitis Vitamin D deficiency Nutritional Malabsorption Impaired synthesis Hepatic dysfunction Renal dysfunction Impaired metabolism Vitamin D–dependent rickets Hypoparathyroidism Impaired synthesis DiGeorge syndrome Activating mutations of the calcium-sensing receptor Pseudohypoparathyroidism Other Hypomagnesemia Hungry bone syndrome Fluoride poisoning Clinical manifestations The clinical manifestations of hypocalcemia are dependent on the severity of the abnormality, the rate of decline in serum calcium, and the chronicity of the underlying process Other factors affecting the development of symptoms include acid–base balance and hypomagnesemia Classic acute manifestations of hypocalcemia include neuromuscular instability or tetany, which affects both sensory and muscular function Early or mild symptoms include paresthesias of the perioral region, hands and feet, and muscle cramps More severe symptoms include seizure, laryngospasm, and bronchospasm Classic physical