Calcium citrate is a type of calcium supplement that is made by combining calcium with citric acid. It is a more easily absorbed form of calcium compared to other forms of calcium supplements. Calcium citrate is commonly used to prevent or treat low levels of calcium in the blood, as well as to support bone health and prevent osteoporosis, muscle diseases, hypoparathyroidism, and osteomalacia. It may also be used in certain medical conditions that cause calcium deficiency, such as chronic kidney disease.