Calcium plays many roles in the body including teeth and bone health, clotting, neurotransmitter function, muscle contraction and enzyme activity. May be elevated due to alkalosis, kidney dysfunction, hyperparathyroidism, cancer, excess Vit D intake, adrenal insufficiency, excess Vit A intake. May be decreased due to poor intake or absorption, hypoparathyroidism, Vit D deficiency, magnesium deficiency.