Calcium is a mineral you need for muscle action and healthy bones. You absorb it from dairy products, calcium supplements, and green, leafy vegetables.

Your bones and teeth are a storage locker for almost all the calcium in your body. Normally, just a little bit of calcium is taken out of storage and moved into your bloodstream at any one time.

Too much calcium in your blood, hypercalcemia, can make you feel sick to your stomach, confused, irritable—and can even send you into a coma! Too little calcium, hypocalcemia, can cause depression, numbness, seizures, confusion, or painful muscle spasms. In the long run, hypocalcemia can damage your bones. (See Module 16—Long-term Effects of Dialysis to learn more.)