Comments on an evaluation of a kit for the determination of calcium in serum and urine.

Effects of acute and chronic desipramine treatment. We compared an immunochemical method for determination of creatine kinase (CK; EC 2.7.3.2) and lactate dehydrogenase (LD; EC 1.1.1.27) activities with the conventional electropho-retic method. Of the 105 patients included in this study, 58 were in the intensive-care unit with a preliminary diagnosis of myocardial infarction; the other 47 had developed chest pain during hospitalization for other reasons. Total CK and LD activities were determined with kinetic procedures, with Dow and Abbott reagents, respectively , in an ABA-100 discrete analyz-er. Total CK activity was assayed by the method of Rosalki (1), LD activity by use of the lactate-to-pyruvate reaction (2). Agarose electrophoresis (Cor-ning) was used to determine CK and LD isoenzymes. The CK bands were evaluated under ultraviolet light (254 nm), the results being recorded as negative , trace, or positive. The LD-1/LD-2 ratio was determined for all patients. Those with a ratio of 1 were recorded as positive, those with a ratio <1 as negative. For immunochemical assays of CK-MB and LD-1 we used the kit assays, NJ. The mean (and SD) value for 165 other patients without myocar-dial infarction were 3.22 (SD 2.84) UIL for CK-MB and 42.34 (SD 16.94) U/L for LD-1. On the basis of these results we selected a cutoff point of 12 UIL for CK-MB and 95 UIL for LD-1 as being positive for myocardial infarction. Values of 10-12 U/L for CK-MB and 90-95 U/L for LD-1 were considered equivocal. The diagnosis of myocardial in-farction was established on the basis of clinical information, electrocardio-graphic evidence, and positive values for CK-MB and LD-1. Of 14 patients with clinical and electrocardiographic evidence of acute myocardial infarc-tion, 12 had immunochemical values exceeding the two cutoff points, a positive MB band, and LD-1ILD-2 ratio >1. In three patients LD-1 appeared before the LD-1/LD-2 ratio became positive; in the other nine patients they both appeared on the same day. In the non-myocardial infarction group (93 patients) a CK-MB value exceeding the cutoff was observed in six, while the LD-1 remained negative, suggestive of ischemic myocardial injury.