One wouldn't buy a "user unfriendly" computer, but a major problem facing all clinicians is a system of "user unfriendly" enzyme units. The Dallas-Fort Worth metroplex illustrates this. Table 1 shows that no two hospitals have the same profile for five common tests. A dictated summary from one is unintelligible to a physician from another. At two hospitals in Arlington, Texas, upper limits of lipase values were 300 U/L and 24 U/L, respectively. A physician telephoning for a laboratory result may thus miss a diagnosis of pancreatitis! The normal lactate dehydrogenase upper limit of normal at one hospital is 618 U/L and at the other is 172 U/L! Moreover, lipase, amylase, and lactate dehydrogenase normal levels all changed two- to threefold at one or the other during the past 4 years. Referring physicians pass along numbers with different normal values than those of the receiving physicians. We have a Tower of Babel locally, regionally, nationally, and internationally! Enzyme anarchy sets the stage for error.

For at least 25 years, many have suggested that the upper limit of normal should be set at 100 and that subsequent values be expressed through ratios; thus, a value of 200 would be twice normal, and so on. All enzymes would have the same normal value, and biochemists could make technical changes without altering clinical comprehension. Laboratory purists might instead favor standard deviations, but this is impractical for most laboratories. Clinicians think and practice in arithmetic ratios: "The alkaline phosphatase is 10 times normal." Trying to understand enzyme significance decreased my reading speed to subzero during Talente and colleagues' superb review of adult glycogen storage disease [1]. The review even included a Table of conversions to SI units and a reference to the clinicians' SI unit nightmare that was published in Annals [2].

As a busy gastroenterologist, I find instantaneous appreciation of enzyme significance critical: Adjustment to 100 for normal values would also show degrees of abnormality because, as with alkaline phosphate values, low values can be important. Normalized units eliminate the need to make telephone calls to strange laboratories, to wait forever to get through computerized messages, and to burn more precious time while normal ranges are hunted down. Our journals should require authors to report enzyme values as both traditional or SI units and as units "normalized" to an upper limit of 100.