Lactate Dehydrogenase Isoenzyme Patterns

Quantitation of isoenzymes of lactate dehydrogenase by electrophoresis aids in diagnosis of diseases such as hepatitis and myocardial infarction. For accurate results, knowledge of isoenzyme distribution in various tissues and the half-life of each isoenzyme is important.     

Improved column method for separating lactate dehydrogenase isoenzymes 1 and 2

Lactate dehydrogenase (LD) isoenzymes 1 and 2 in human serum were separated on a column of diethylaminoethyl-Sephadex. Samples layered on mini-columns were eluted with buffered sodium chloride (100, 150, and 200 mmol/liter). Lactate dehydrogenase activity in column effluents was measured by the Wacker method, and their isoenzyme content was evaluated by electrophoresis on polyacrylamide gel. Results for column-fractionated LD-1 and LD-2 were expressed in two ways: LD-1/LD-2 ratios and total LD-1 + LD-2 activities. The former is a more specific indicator of myocardial infarction than the latter. Sera from 10 patients with acute myocardial infarction (increased creatine kinease isoenzyme MB activity) exhibited ratios in the range of 0.92 to 1.56, ratios for 10 patients without heart disease (normal creatine kinase MB) ranged from 0.33 to 0.69.     

Simultaneous separation of serum creatine kinase and lactate dehydrogenase isoenzymes by ion-exchange column chromatography.

Lactate dehydrogenase isoenzymes were partially separated by use of a previously described column technique for creatine kinase [Clin. Chem. 20, 36 (1974)]. Extracts of lactate dehydrogenase-rich tissues were used to evaluate column resolution. Samples layered on mini-columns containing DEAE-Sephadex were eluted with Tris-buffered sodium chloride (100 and 200 mmol/liter). Lactate dehydrogenase activity in column effluents was measured by the Wacker method, and their isoenzyme content was assessed by electrophoresis on polyacrylamide gel. Dehydrogenase isoenzymes 3, 4, and 5 were separated from isoenzymes 1 and 2, and the separation was tissue-specific and reproducible. The electrophoretic technique for isoenzymes 3, 4, and 5 gave values about 20% lower than did the column technique. Sera from 15 healthy laboratory technicians contained total lactate dehydrogenase, isoenzymes 1 and 2, and isoenzymes 3, 4, and 5 in the ranges 94 to 152, 34 to 64, and 38 to 75 U/liter, respectively. Activities of sera from 15 patients with acute myocardial infarction (total lactate dehydrogenase) ranged from 212 to 800 U/liter and lactate dehydrogenase isoenzymes 1 and 2 ranged from 138 to 628 U/liter. Lactate dehydrogenase and creatine kinase isoenzymes were rapidly and easily measured after being simultaneously separated. The procedure is specific and sensitive for following the post-infarct time course of changes in isoenzyme activities.     

Lactate dehydrogenase isoenzyme-1/total ratio: accurate for determining the existence of myocardial infarction

We have gradually revised our medical protocols for measuring creatine kinase MB isoenzyme (CK-MB) and lactate dehydrogenase isoenzyme-1 (LD-1) because of identifiable problems in the use of an interpretation of CK-MB isoenzyme associated with slowly evolving or small myocardial infarct, the use of thrombolytic therapy, or burn and trauma, each of which affects the rate of appearance and composition of isoenzymes present. Despite recent evidence of the efficacy of LD-1 isoenzyme measurement in the first 12 to 24 h of myocardial infarction, this test is not widely used because of overstated assumptions about the value of CK-MB. Here we studied the adequacy of the current isoenzyme assays by determining the value of CK-MB and LD-1 at optimum serum sampling times and establishing the contribution of individual and combined predictors to diagnostic efficiency. We conclude that the LD-1/total LD activity ratio in serum is superior to measurement of CK-MB or LD-1, or both, in the diagnosis of acute myocardial infarction. Moreover, this ratio is most valuable when interpretation of the result for CK-MB isoenzyme is equivocal in patients with small or evolving myocardial infarcts.     

Atypical patterns of lactate dehydrogenase isoenzymes in acute myocardial infarction

Total lactate dehydrogenase (LD; EC 1.1.1.27) activity in serum and LD isoenzymes were quantified in 190 patients with acute myocardial infarction (AMI) 24, 48, and 72 h after admission. In 90% of the 570 blood specimens an LD isoenzyme pattern typical of AMI (LD-1/LD-2 greater than 0.76) was found. The other 56 blood specimens showed an LD isoenzyme pattern atypical of AMI (LD-1/LD-2 less than 0.76). They were divided into three groups: 28 specimens with isomorphic pattern (relative increase in all five LD isoenzymes); 18 with relatively increased LD-3 proportion (greater than 35%); and 10 specimens with increased LD-5 proportion (greater than 10%). No difference was found in mean total LD activity in serum between the typical isoenzyme group and the three atypical groups. The LD isomorphic pattern was found in 60% of AMI patients complicated by cardiogenic shock. Fifty percent of AMI patients admitted with pulmonary edema showed increased LD-3 proportion and half of the patients with AMI and congestive heart failure, predominant right, demonstrated increased LD-5 proportion. We conclude that although most patients with AMI present at diagnosis with a typical LD isoenzyme pattern, it is important to recognize that some may present with atypical LD isoenzyme patterns, which may be associated with specific AMI complications.     

Detection of alcoholic cardiomyopathy by serum enzyme and isoenzyme determination

Serum creatine kinase and lactate dehydrogenase isoenzymes were studied in 73 patients with alcoholism, including two patients with clinical alcoholic cardiomyopathy and 28 patients with haemodynamic evidence (systolic time interval abnormality) of disordered myocardial function. No isoenzyme abnormalities suggestive of myocardial injury were observed. We conclude that isoenzyme examination is unsuitable for the early detection of myocardial damage from alcohol.     

Selective determination of lactate dehydrogenase isoenzyme 1 in serum after inhibition by 1,6-hexanediol

A rapid selective method for measuring the activity of lactate dehydrogenase isoenzyme LD-1 in serum by using 1,6-hexanediol as an inhibitor of the M-subunit was developed. Hexanediol was added to serum at a final concentration of 0.7 mol/l. After incubation at 30 degrees C for 15 min, the activity was measured with an automatic analyser. The inter-assay coefficient of variation was 6.9% for the lactate dehydrogenase isoenzyme LD-1 measurement. The results obtained from the sera of 100 patients analysed by the proposed selective method and by the conventional electrophoretic method, respectively, showed an excellent correlation. This selective method was used to determine the lactate dehydrogenase isoenzyme LD-1 activity of sera from patients with acute myocardial infarction, and the results were correlated well with those obtained by the immunological, Roch Isomune method. Addition of 1,6-hexanediol did not affect the measurement of activities of other enzymes such as alkaline phosphatase, gamma-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase.     

Enzymatic assessment of myocardial injury after infarction or cardiac surgery. Is isoenzyme analysis required?

Estimation of enzyme release in plasma requires knowledge of the fractional catabolic rate constant (FCR) for the elimination enzyme activity from plasma. However, the total plasma content of such enzymes usually consists of several isoenzymes with different values of FCR. Thus, the use of a single overall value for FCR may cause error. This problem was studied by determination of the plasma isoenzyme activities of creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alpha-hydroxybutyrate dehydrogenase in patients after cardiac surgery and after acute myocardial infarction. Values of FCR and the cumulative release of activity in plasma are estimated for separate isoenzymes and for total enzyme activity. Results are compared with the enzyme content of myocardium, skeletal muscle and blood cells. It is concluded that isoenzyme separation is not required for the quantitative use of such data. The implications for the validation of enzymatic estimation of cardiac injury are discussed. The results indicate that local inactivation of enzymes after cardiac injury must be limited.     

Lactate dehydrogenase isoenzyme pattern in sera of patients with malignant diseases

Total lactate dehydrogenase (LDH; EC 1.1.1.27) activity and the percentage distribution of LDH isoenzymes were determined in 127 patients with malignant diseases. A shift in the isoenzyme patterns was observed toward the M-type, with an increase in the percentage of LDH-4 and LDH-5 isoenzymes and a slight increase in total LDH activity of all patients. Serum samples from 68 of the patients contained an abnormal isoenzyme of LDH, "LDH-1 ex," that, on agarose gel electrophoresis at pH 8.6, migrated between albumin and LDH-1 isoenzyme. Chemotherapy, radiotherapy, or surgical removal of the tumor was accompanied by disappearance of this abnormal isoenzyme. The heat stability of LDH-1 ex isoenzyme appears to be similar to that of LDH-1 but greater than that of the other LDH isoenzymes. Statistical analysis of these data demonstrated a significant correlation between malignancy and the appearance of LDH-1 ex isoenzyme (P less than 0.001). In contrast, the relationship between LDH-1 ex isoenzyme and metastasis or anatomical location of the malignancy is not statistically important (P less than 0.1).     

Two methods compared for measuring LD-1/total LD activity in serum

We present evidence for the utility of an improved assay for the activity of lactate dehydrogenase (EC 1.1.1.27) isoenzymes 1 and 2 in serum, involving inhibition of the H-subunit of LD by pyruvate at pH 7.1. Results correlate well with the LD-1/total LD ratio as evaluated by immunological assay and, as an index to infarct, the method is superior to either the change in CK-MB activity or to the LD-1 activity or to a combination of these tests, as is the percentage of LD-1 to total LD activity. Moreover, the percentage inhibition of LD activity by pyruvate may have an advantage over other methods of isoenzyme fractionation because of its smaller population CV for patients with acute myocardial infarction than is true of other methods. We also demonstrate how, using a linear discriminant analysis, we compared this method with alternative methods. We determined that evaluation of CK-MB isoenzyme contributes no information in addition to that obtained from the LD-1 isoenzyme.     

Cardiac enzyme changes in myxedema coma

A 74-year-old man with myxedema and hypothermia had increased activities in plasma of creatine kinase (CK; EC 2.7.3.2), aspartate aminotransferase (AST; EC 2.6.1.1), and lactate dehydrogenase (LD; EC 1.1.1.27) and increased proportions of CK-MB (up to 20% of total CK) and LD1 isoenzymes, but no clinical or investigational evidence of associated myocardial infarction. This case illustrates that plasma enzyme activity and isoenzyme profiles in such clinical settings should be interpreted with caution, because increases in CK-MB and LD1 may relate to myxedema coma or hypothermia (or both) rather than to myocardial infarction.     

IgA-CK-BB complex with CK-MB electrophoretic mobility can lead to erroneous diagnosis of acute myocardial infarction

This patient, on admission, presented with a tentative diagnosis of myocardial infarction: the electrocardiogram showed a nonspecific ST-segment and T-wave abnormalities, and total creatine kinase (CK; EC 2.7.3.2) activity was slightly increased (238 U/L). However, a high electrophoretic value for CK-MB (50% of total CK activity) and the electrophoretic pattern of lactate dehydrogenase (EC 1.1.1.27) isoenzymes ruled out myocardial infarction. The isoenzyme migrating as CK-MB was found later to contain no immunologically normal CK-M subunits, and it was bound to IgA. A mixture of the patient's serum and a human serum control containing all CK isoenzymes showed altered electrophoretic mobility only for CK-BB, indicating that the patient's serum contained antibodies to the B unit of CK. Elution from a Sephadex G-200 column showed that the peak at which most of the anodic CK was eluted corresponded to a molecular mass of approximately 200 kDa. Evidently this atypical isoenzyme was an IgA-CK-BB complex. Because this macro CK type 1 can mimic CK-MB, it may therefore be a source of confusion.     

Serum isoenzyme pattern of creatine kinase and lactate dehydrogenase in various animal species

The creatine kinase and lactate dehydrogenase isoenzyme pattern were determined in the serum of normal and untreated rats, rabbits, dogs, monkeys and pigs. The relative distribution of all isoenzymes in the serum and an electrophoretic pattern for each animal species are presented. The isoenzyme serum pattern showed a great variation between the species. The diagnostic value of serum creatine kinase isoenzyme MB and lactate dehydrogenase isoenzymes 1 and 2 in predicting cardiac lesions in different animal species is briefly discussed.     

Application of nicotinamide-adenine dinucleotide analogs for clinical enzymology: a spectrophotometric method for clinical analysis of lactate dehydrogenase patterns with the use of a nicotinamide-adenine dinucleotide analog.

The activities of porcine lactate dehydrogenase (LHD) isoenzymes were analyzed using nicotinamide-adenine dinucleotide (NAD) or its analogs as a cofactor, with varying concentrations of L-lactate from 13 to 530 mM. The greatest differences between H4-type and M4-type isoenzymes in reaction rates were observed when their activities were compared in a reaction mixture containing 530 mM lactate and NAD, and also in a system of 13 mM lactate with thionicotinamide-hypoxanthine dinucleotide as a cofactor. The ratio of the LDH activity exerted in the former reaction mixture to that exerted in the latter was termed the N/T value. The N/T values of porcine H4 and M4 isoenzymes were 0.49 and 9.33, respectively. The N/T values of other three isoenzymes (H3M1, H2M2 and H1M3) were calculated by assuming that the single subunits H1 and M1 contribute one-fourth of the values of 0.49 and 9.33, respectively, and a given isoenzyme which is a combination of four subunits of H and M comprises the sum of their values. The calculated values agreed fairly well with the experimental results. The N/T value method was found to be applicable to human LDH isoenzymes, and sera from various patients were analyzed in comparison with hormonal sera. The method is particularly suitable for the numerical expression of LDH isoenzyme profiles.     

Systemic short-term fibrinolysis with high-dose streptokinase in acute myocardial infarction: time course of biochemical parameters

The course of plasma catalytic activities of total creatine kinase, creatine kinase isoenzyme MB, total, cytoplasmatic and mitochondrial aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, glutamate dehydrogenase and concentrations of myoglobin, urea, acidic alpha 1-glycoprotein and creatinine were followed in 33 patients suffering from acute myocardial infarction. All patients were randomized in a double-blind, prospective study. One group (18 patients) was infused with streptokinase 1.5 X 10(6) units/90 minutes; the control group received routine continuous i.v. heparin treatment (1000 units/h). Ten hours after completion of the study protocol, treatment of both groups of patients was continued with heparin, 1000 units/h and Aspisol, 1 g/day2). Streptokinase treatment induced earlier wash-out and therefore earlier peak levels of several enzymes: total creatine kinase (11 hours), creatine kinase isoenzyme MB (6 hours), total and cytoplasmatic aspartate aminotransferase (6 hours) and lactate dehydrogenase (9 hours). Total creatine kinase peak catalytic activity and myoglobin peak concentration were higher in the group receiving thrombolytic therapy. A significantly different course of catalytic activity between both treatment groups was found for total creatine kinase and creatine kinase isoenzyme MB, total and cytosolic aspartate aminotransferase, lactate dehydrogenase and alpha-hydroxybutyrate dehydrogenase. The course of mitochondrial aspartate aminotransferase catalytic activity was different only 12 hours after the beginning of treatment. The shift of several catalytic activities to an earlier peak level in plasma may indicate reperfusion of ischaemic myocardium due to thrombolytic therapy.     

Cardiac enzymes. How to use serial determinations to confirm acute myocardial infarction.

Although acute myocardial infarction can be diagnosed on the basis of clinical history, electrocardiographic (ECG) findings, and abnormalities of creatine kinase (CK) and lactate dehydrogenase (LDH) enzyme levels, measurement of cardiac enzyme levels is the most reliable way to confirm or exclude the diagnosis. If the MB isoenzyme of creatine kinase (CK-MB) remains normal during the 48 hours after the suspected clinical event, acute myocardial infarction can be reliably ruled out; if CK-MB values become elevated and the LDH isoenzyme pattern (LDH2:LDH1 ratio) becomes "flipped," the diagnosis can reliably be made. However, if CK-MB values become elevated but the LDH isoenzyme pattern remains normal, the diagnosis is less firm and ECG and myocardial imaging techniques may be needed to confirm or exclude myocardial infarction.     

LD1 and several ratios of lactate dehydrogenase isoenzymes in acute myocardial infarction

The sensitivity and specificity of three parameters--ECG, creatine kinase MB isoenzyme and LD isoenzymes--were compared in 385 consecutive patients hospitalized for clinically suspected acute myocardial infarction (MI). In 147 patients acute MI was diagnosed on the basis of three parameters. In the remaining 238 patients acute MI was ruled out. Decision values for LD1, LD1/total LD, LD1/(LD2 + LD3 + LD4 + LD5), and the sum of LD1/LD2 + LD1/total LD + LD1/LD2 + LD3 + LD4 + LD5) were selected as 70 U/L, 0.33, 0.5, and 1.79, respectively for the test positivity of LD isoenzymes for acute MI. These new criteria, with the decision values, are proposed as test positivity of CK-MB and LD isoenzymes for acute myocardial infarction.     

Myocardial infarction?--a conflict between electrocardiographic changes and biochemical data.

We present a case of hypovolemic shock accompanied by electrocardiographic changes classically associated with acute myocardial infarction. Prompt therapeutic intervention, which included correction of the hypovolemic shock, resulted in stabilization of the patient's clinical course, increased activities of the cardiac-specific enzymes in serum were not documented. Serial electrophoretic determinations of the isoenzymes of serum lactate dehydrogenase did not show the characteristic changes associated with myocardial infarction. Accurate determination of the serum isoenzymes provided valuable diagnostic information which, accompanied by the patient's clinical improvement, militated strongly against the occurrence of myocardial infarction.     

Specificity of autoantibodies to lactate dehydrogenase isoenzyme subunits

We studied serum from 12 unrelated patients with variant electrophoretic patterns for lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes characteristic of LD-immunoglobulin complexes. Immunoglobulin class was identified in four cases. In all 12 cases, mixing the patient's serum with control serum altered the mobility of normal LD isoenzymes to that of the variant. To determine antigenic specificity, we mixed ammonium sulfate-precipitated fractions of patient's samples with purified LD1 (H tetramer) or LD5 (M tetramer) prepared by anion-exchange chromatography. In six cases the fractionated antibody displayed a pure M-subunit specificity. In four cases it acted against both M tetramers and H tetramers, and in two cases the antibody affected the migration only of LD isoenzymes containing both M and H subunits (i.e., hybrid isoenzymes). Depending on the relative excess of antibody or LD5 in such mixtures, various different anomalous electrophoretic patterns were produced. These results indicate that apparent differences between variant LD isoenzyme patterns in whole serum of different individuals can arise from autoantibodies with similar reactivities being present in various ratios of antigen to antibody.     

Mass concentration of creatine kinase MB isoenzyme and lactate dehydrogenase isoenzyme 1 in diagnosis of perioperative myocardial infarction after coronary bypass surgery

Recent advances in methodology allow the mass concentration of creatine kinase MB isoenzyme (CK-MB), and of lactate dehydrogenase isoenzyme 1 (LD1) to be determined quickly and easily as routine, emergency tests. We evaluated these tests as diagnostic criteria of perioperative myocardial infarction (PMI) after coronary bypass surgery. These tests were compared with the usual measurements of CK-MB activity by immunoinhibition and LD1 by electrophoresis and with other biological markers of myocardial infarction such as total CK, total LD, and aspartate aminotransferase. Sixty-one patients who underwent coronary bypass grafting were followed pre- and postoperatively by enzyme determinations and electrocardiography; a subgroup was monitored by myocardial scintigraphy. CK-MB mass appeared to be the best marker of PMI during the first 48 h, although LD1 was the marker of choice from days 2 to 4.