Alkaline phosphatase
During the early stage, an x-ray will not be helpful because there is no calcium in the matrix. (In an acute episode which is not treated, it will be 3– 4 weeks after onset before the x-ray is positive.) Early laboratory tests are not very helpful. Alkaline phosphatase will be elevated at some point, but initially may be only slightly elevated, rising later to a high value for a short time. Unless weekly tests are done, this peak value may not be detected. It is not useful in patients who have had fractures or spine fusion recently, as they will cause elevations.