Many events take place in disease, which are ostensibly removed from the site of symptom or complaint. For example, in myocardial infarction, there is a change in the level of serum enzymes, which rises or drops during the course of the episode. Or, in shock there is an electrolyte disturbance, which is in a sense the ecological aspect of the condition. These changes in levels are often so predictable that they may be used as a point in diagnosis, or in prognosis to assess the course of a disease, its repair or exacerbation.
It is only about 15 years since the determination of serum enzymes has been used regularly in diagnosis and only about 10 years since fractionation into isoenzymes refined their diagnostic use.
Enzymes are ubiquitous in tissues—including bone—and their determination represents a particularly useful procedure in diagnosis and prognosis. Since their predominance often differs from organ to