How to Calculate the Calcium-Phosphorus Product

Calcium and phosphorus are two critical elements in the function of a variety of different physiological processes within the body including muscle contraction, nerve transmission and bone resorption. Although they function in many of the same processes, normal blood concentration levels of the two minerals is crucial for optimal health. High levels of phosphorus, in particular, may result in calcium deficiency leading to a variety of medical complications such as osteoporosis, neuromuscular spasms and cardiovascular problems. The calcium phosphate product is utilized in medicine as a means of monitoring the levels of these two minerals in patients with chronic kidney disease, or CKD. The kidney functions to eliminate phosphorous from the body, as well as to resorb the majority of calcium back into blood. Thus, the calcium phosphorus product must stay below a certain threshold in patients with kidney disease.

Identify the serum calcium level. This is accomplished through blood tests ordered by a physician. The normal blood calcium range is 8.5 to 10.2 mg/dL.

Identify the serum phosphorus level 24. This also accomplished through laboratory blood testing. The normal blood phosphorus range is 2.4 to 4.1 mg/dL.

Multiply these two values together to determine the calcium-phosphorus product. For example; assume the serum calcium level is 9.6 mg/dL and the serum phosphorus level is 3.2 mg/dL 4. The calcium-phosphorus product for these two values is 30.7 mg^2/dL^2 4. In patients with chronic kidney disease, the calcium-phosphorus level should remain below 55 mg^2/dL^2.