Calcium is the most abundant mineral in the body, with 99% of the body’s calcium found in bones and teeth. In addition to formation of strong bones and teeth, calcium is an important component of many enzymes important in blood clotting, muscle contraction, regulation of the heartbeat and transmission of nerve impulses. Calcium works with many other nutrients including vitamins D and K, magnesium and phosphorus. Deficiency of calcium may set up conditions in which calcium is depleted from the bones resulting in weakness and deformity. Deficiency of calcium may contribute to osteoporosis.

Studies have shown people get much less than the RDA of calcium from their diet. Because calcium is so important in many enzymes, the body maintains blood calcium levels within a very narrow range. However, a number of conditions including low parathyroid hormone, vitamin D deficiency, kidney disease, magnesium deficiency, protein deficiency and increased calcium requirement can cause low blood calcium.

Low blood calcium causes muscle spasm. Elevated blood calcium can occur with high parathyroid hormone, hyper- or hypothyroid conditions, bone metastasis, vitamin D toxicity, excess intake or absorption of calcium, Addison’s disease and with thiazide diuretics. High blood calcium may be asymptomatic or can cause constipation, nausea and vomiting, increased urination, thirst, muscle weakness, kidney failure, irritability, confusion, psychosis and coma. Both low and high blood calcium require medical treatment.