Effect of blood transfusion on serum 'cardiac' enzyme activities.

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The serum activities of aspartate transaminase (AsT) , creatine kinase (CK), and lactate dehydro­ genase (LD) or hydroxybutyrate dehydrogenase (HBD) rise after a myocardial infarct. Unfortunate­ ly, these enzymes are not specific for heart muscle nor do myocardial infarcts occur only in patients whose enzyme levels are known to have been within the reference range before infarction. The present study was prompted when an elderly woman developed chest pain during the course of a blood transfusion for chronic anaemia and was found to have a moderately raised AsT, a high HBD, and an inconclusive electrocardiogram. Although it is well known that erythrocytes contain AsT and LD isoenzymes and that after blood transfusion there is a regular though variable breakdown of transfused erythrocytes, we were unable to find any reference to changes in serum levels of AsT, CK or LD in the recipient after blood transfusion. Patients and methods Twenty patients aged between 54 and 88 years who were undergoing blood transfusion for chronic normochromic normocytic anaemia, secondary to chronic malignant, renal or hepatic disease in eight and of unknown aeriology in 12, were investigated. No patient had any evidence ofmyocardial infarction or ischaemia. Their pre-transfusion haemoglobin values ranged from 5·4 to 10·7 g/dl, and each received 4 units of blood. Serum AsT, CK, and HBD activities were measured in each patient before transfusion and daily for the first five days after the transfusion. AsT activity was measured using optimised automated Boehringer kits and total CK using NAC-activated automated Boehringer kits on a Clinicon LKB kinetic analyser at 37°C. HBD activity was measured using optimised manual Boehringer kits on a Unicam SP 1800 spectrophoto­ meter at 37°C. Student's t test was used to compare the daily group mean enzyme activities. Results AsT patients had normal AsT values on each occasion on which they were measured, and there was no significant rise in any individual patient or in the group mean values (reference range 5-40 U II). CK