Blood Calcium Levels - Hypocalcemia vs. Hypercalcemia: In order for the heart and muscles to function properly, as well as to ensure bone development, normal blood calcium levels are essential. When the blood has too little calcium levels, the condition is known as hypocalcemia. In contrast, hypercalcemia is a condition in which the calcium levels in the blood are above normal. Too much or too little of calcium in the blood can weaken bones, create kidney stones, and interfere with proper heart and brain function.