The infant's heart defects may lead to heart failure, or there may be seizures and other evidence of a low level of calcium in the blood (hypocalcemia).
Vitamin D deficiency impairs the absorption of dietary calcium and can provoke calcium deficiency (hypocalcemia) even when adequate calcium is consumed.
Severe phosphate toxicity can result in hypocalcemia and in various symptoms resulting from low plasma calcium levels.
Symptoms of hypomagnesemia, such as twitching and convulsions, may actually result from the hypocalcemia.
Hypocalcemia in a child with DiGeorge syndrome is unusually difficult to treat.