Determination of Serum “Acid” Phosphatase Activity in Differentiating Skeletal Metastases Secondary to Prostatic Carcinoma from Paget's Disease of Bone

Abstract

Ordinarily, the roentgen criteria for distinguishing between osteitis deformans and osteoplastic skeletal metastases due to prostatic carcinoma (1,2) permit of reasonable certainty in their differentiation. In early stages of either condition, however, when sclerotic areas are limited to the bony pelvis and spine, it may be difficult or impossible to establish a definite diagnosis roentgenographically. Moreover, as it is in the older age group that clinical examination of the prostate gland for carcinoma is prone to indecisive results, it not infrequently happens that the prognostically significant distinction between a metastasizing carcinoma and Paget9s disease is made, if at all, only by biopsy or after protracted observation. When Kay first discovered (3) the now well substantiated (4) increase in serum phosphatase activity in Paget9s disease—the only known abnormality of the blood of consistent occurrence in that condition—it was thought that this observation might prove helpful in the clinical problem under consideration. Since widespread osteoplastic metastases, most commonly secondary to prostate carcinoma, are associated with similarly increased phosphatase values, however (4, 5, 6, 7, 8, 9), it soon became apparent that the determination as ordinarily practised (“alkaline” phosphatase activity) is of no value in differentiating these two conditions (6, 9).