Which of the following statements accurately reflects the normal total serum calcium range?

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Normal total serum calcium is read as a single value that reflects both the bound and free calcium in the blood. In healthy adults, this combined level typically sits between about 8.5 and 10.5 mg/dL. This range is used because it captures the physiologic levels at which calcium can perform its essential roles in bone mineralization, neuromuscular function, and coagulation without signs of deficiency or excess.

If calcium is above this range, it suggests hypercalcemia, which can arise from causes like overactive parathyroid glands, certain cancers with bone involvement, or excessive vitamin D. If it falls below, it suggests hypocalcemia, which can result from hypoparathyroidism, severe magnesium deficiency, or other conditions affecting calcium balance.

Be aware that some laboratories report slightly different reference ranges (for example, 8.8–10.3 mg/dL) and that total calcium can be influenced by albumin levels. When albumin is low, total calcium may appear low even if ionized calcium is normal, so clinicians sometimes adjust for albumin or measure ionized calcium for accuracy.