Creatine kinase MB isoenzyme in dermatomyositis: a noncardiac source

Clinical analysis of the serum muscle enzyme spectrum of patients with newly diagnosed Sheehan's syndrome

We investigated the factors associated with serum muscle enzyme elevation in patients with Sheehan's syndrome. A total of 48 patients who were newly diagnosed with Sheehan's syndrome were included and divided into 3 groups: Group 1, creatine kinase (CK) ≥ 1000 U/L; Group 2, 140 < CK < 1000 U/L; and Group 3, CK ≤ 140 U/L. Differences in serum muscle enzymes, serum electrolytes, blood glucose and hormones were compared among the 3 groups. A Spearman correlation analysis and multiple linear regression analysis were performed on serum muscle enzymes and the other variables. Four patients in Group 1 underwent electromyography. Fourteen, 26 and 8 patients were divided into Group 1, Group 2, and Group 3, respectively. The levels of plasma osmolality, serum sodium, free triiodothyronine (FT3) and free thyroxine (FT4) in Group 1 were lower than those in Group 3 at admission (P < .05). There were significant differences in CK, CK-MB, aspartate aminotransferase, lactate dehydrogenase, and alpha-hydroxybutyrate dehydrogenase among the three groups (P < .05). CK was correlated with serum sodium (r = -0.642, P < .001), serum potassium (r = -0.29, P = .046), plasma osmolality (r = -0.65, P < .001), FT3 (r = -0.363, P = .012), and FT4 (r = -0.450, P = .002). Moreover, creatine kinase isoenzyme-MB (CK-MB) was correlated with serum sodium (r = -0.464, P = .001) and plasma osmolality (r = -0.483, P < .001). The multiple linear regression showed that serum sodium was independently and negatively correlated with CK (r = -0.352, P = .021). The electromyogram results supported the existence of myogenic injury. Sheehan's syndrome is prone to be complicated by nontraumatic rhabdomyolysis, with both a chronic course and acute exacerbation. Serum muscle enzymes should be routinely measured. For patients with CK levels > 1000 U/L, a CK-MB/CK ratio < 6% can be a simple indicator to differentiate rhabdomyolysis from acute myocardial infarction. Abnormal serum muscle enzymes observed in Sheehan's syndrome may be associated with hypothyroidism and with hyponatremia in particular.

The role of biomarkers in the diagnosis and risk stratification of acute coronary syndrome

Coronary artery disease is a growing concern. Although traditional biomarkers, such as troponins and creatine kinase, play a central role in the diagnosis, risk stratification and management of coronary artery disease, they are unable to detect myocardial ischemia in the absence of necrosis. Therefore, early detection of ischemia in patients presenting with acute coronary syndrome still remains a burning question. High-sensitivity troponin is evolving as a reliable biomarker in this regard and has been absorbed into clinical practice. Biomarkers are currently the focus of immense interest as it not only helps with diagnosis and management but also helps to understand the pathophysiology of the disease process. In addition, analysis using a multimarker strategy has also proven to be a very useful tool in risk stratification. This review will focus on the biomarkers and its application in the diagnosis and risk stratification of acute coronary syndrome.

Cardiovascular diseases are a common group of diseases that affect a large population and account for a significant number of deaths worldwide. Acute coronary syndrome (ACS) is a growing public health concern, where inadequate blood flow to the heart muscle results in reversible or irreversible damage to the cardiomyocyte. Early detection of ACS is crucial to deliver appropriate timely therapy to prevent myocardial necrosis and heart failure. Biomarkers are measurable and quantifiable biological substances that are used as indicators in the early diagnosis and management of patients with ACS. This article provides an overview of this topic and provides suggestions for the future.

The heart in sporadic inclusion body myositis: a study in 51 patients

The purpose of this study was to explore the prevalence and nature of cardiac abnormalities in sporadic inclusion body myositis (sIBM). Fifty-one sIBM patients were cross-sectionally studied using history-taking, physical examination, measurements of serum creatine kinase activity, the MB fraction (CK-MB), cardiac troponin T (cTnT) and I (cTnI), a 12-lead electrocardiogram (ECG) and 2-dimensional echocardiography. Present cardiac history was abnormal in 12 (24%) out of 51 patients, 12 (24%) patients had abnormalities on ECG, mostly aspecific, and in 12 (24%) patients the echocardiograph showed abnormalities. Elevated CK-MB was present in 42 (82%) patients and 40 (78%) had an elevated cTnT in the absence of acute cardiac pathology. In contrast, in one patient (2%) cTnI was elevated. There was no apparent association between elevated biomarkers, ECG or echocardiographic abnormalities. The prevalence of cardiac abnormalities in sIBM does not seem to be higher than would be expected in these elderly patients. Elevated CK-MB and cTnT levels are common, in contrast to cTnI, but do not reflect cardiac pathology.

Significance of assessment of serum cardiac troponin I and interleukin-8 in scorpion envenomed children

In the present study, 41 children in Upper Egypt were admitted to Pediatric Intensive Care Unit, Assiut University Hospital, for scorpion envenomation. They were compared with 15 apparently healthy children of matching age as controls. The victims and controls were subjected to complete clinical examination, full blood count and arterial blood gases analysis. According to severity of scorpion envenomation, 17 children had manifestations of severe envenomation and clinical signs of toxic myocarditis (severe cases), 14 children had moderate manifestations of envenomation without clinical evidence of carditis (moderate cases) and 10 cases showing only mild symptoms of envenomation (mild cases). The serum levels of cardiac troponin I (cTnI) and interleukin-8 (IL-8) beside the enzymatic activities of creatine phosphokinase (CPK), CPK-isoenzyme-MB (CPK-MB) and lactate dehydrogenase (LDH) were determined once for mild cases and controls on admission and twice for severe and moderate cases on admission and after 24. Electrocardiography and measurements of echocardiographic (Echo) of % fractional shortening of left ventricule (% SF), left ventricular ejection fraction (LVEF) and cardiac chambers dilatation were done for severe and moderate cases. All the envenomed victims showed significantly higher mean values of CPK, CPK-MB, LDH, and IL-8 on admission in comparison to control group. cTnI was not detectable in the sera of control group as well as patients of mild envenomation. The mean values of CPK, CPK-MB, LDH, and IL-8 were significantly higher in severe cases while only IL-8 and CPK-MB were significantly higher in moderate cases in comparison with mild cases. The mean values of IL-8, cTnI, CPK, CPK-MB and LDH were significantly higher in severe cases both on admission and on follow-up comparing with moderate cases. The case fatality rate was 12.5% and all were from severe cases with toxic myocarditis. The non-survivors victims showed significant higher mean values of only cTnI on admission and both cTnI and IL-8 on follow up in comparison to the survivors. Significant reduction of % SF and LVEF were noticed among the non-survivors in comparison to survivors. The cTnI showed 100% specificity and sensitivity for diagnosis of myocardial injury in relation to Echo finding in the envenomed victims. In severe cases, cTnI was positively correlated with IL-8 while negatively correlated with %SF and LVEF. In conclusion, cTnI is a specific marker for diagnosis of myocardial injury in scorpion envenomation while other biochemical markers did not show such specificity. Also, IL-8 may be involved in the pathogenesis of myocardial injury of scorpion envenomation. Both cTnI and IL-8 may be useful to forecast the fatal outcome in scorpion envenomation.

Cardiac involvement in myositis

After careful examination, cardiac involvement can be found in certain patients with inflammatory muscle disease. The clinical significance is not always clear, although in some patients profound disturbances can become manifest. Currently, no laboratory assay can be relied on to detect cardiac disease with 100% accuracy. Cardiac troponin I is, however, the best test currently available.

Laboratory testing in the diagnosis and management of idiopathic inflammatory myopathies

Laboratory testing commonly used to assess the idiopathic inflammatory myopathies (IIMs) can be divided into three categories: (1) measurement of serum activities or concentrations of muscle-derived factors--such as enzymes, myoglobin, and other molecules--in order to assess muscle injury; (2) immunologic tests that detect markers of the disease process, including serum autoantibodies that have been associated with myositis; and (3) general laboratory tests that are used to assess the patient's general status and medical condition. The laboratory assessment of muscle-derived factors that reflect muscle injury, and the determination of serum autoantibodies, play valuable roles in the diagnosis and management of the IIM. Enzyme elevations do not correlate with disease activity in all patients, however, and they must be interpreted within the clinical context. Autoantibodies can identify disease subsets with distinctive patterns of clinical manifestations, genetics, responses to therapy and prognosis, but disease-specific autoantibodies are present in only half of patients with IIM. Recent studies have defined additional myositis autoantibodies that may improve our capacity to diagnose and manage the IIM.

[Cardiac manifestations of polymyositis. Apropos of 2 Senegalese cases]

INTRODUCTION

Polymyositis cardiac involvement varies between 37% and 70%. EXEGENESIS: The authors report two cases of polymyositis with myocardial involvement observed in Senegal; the first case is a cardiac failure revealing an acute polymyositis occurring in a 44-year-old woman; the second case is a 34-year-old woman who had polymyositis with tachycardia and dyspnea: in the two cases echocardiography showed a left ventricular concentric hypertrophy with preserved systolic function and altered diastolic function; clinical and echocardiographic resolution were obtained by corticosteroid medication.

CONCLUSION

Myocardial localization is the most common polymyositis cardiac involvement; clinical symptomatology is rare (3.3% to 6%). sometimes revealing polymyositis; electrocardiographic abnormalities are found in 18% to 81% cases and echographic abnormality in 42% cases; cardiac involvement is of bad prognosis.

Laboratory evaluation of the inflammatory myopathies

The laboratory plays an important role in the diagnosis, evaluation, and classification of the heterogeneous group of diseases known as the IIM, which are characterized by chronic muscle inflammation. Serial measurements of the levels of muscle-derived enzymes in serum are the traditional laboratory studies used to follow the clinical course of patients with IIM, although other laboratory tests can also be useful in assessing myositis disease activity. Several markers of immune system activation, including cytokines and lymphocyte markers, show promise as possibly more sensitive measures of myositis disease activity. Discovery of a unique group of MSAs over the past decade has provided an immunologic basis for defining relatively homogeneous subsets of patients who share similar clinical features, disease courses, and responses to therapy. Future investigations of novel immunologic activation markers, as well as the cloning and expression of target autoantigens of the MSAs, should allow better diagnostic assays, enhanced prognosis, and a better understanding of the pathogenesis of these disorders.

Early assessment of reperfusion therapy using cardiac troponin T

OBJECTIVES

The purpose of this study was to investigate the utility of cardiac troponin T for early assessment of reperfusion therapy.

BACKGROUND

Several biochemical markers are used for early noninvasive detection of reperfusion during intravenous thrombolytic therapy. However, cardiac troponin T, a new myocardial-specific marker, has not been used previously for this purpose.

METHODS

We measured troponin T and creatine kinase, MB isoenzyme (CK-MB) levels in 38 patients with acute myocardial infarction whose infarct-related artery was totally occluded before reperfusion therapy. Subjects comprised 14 patients with successful angioplasty (group 1), 12 patients with successful thrombolytic therapy (group 2) and 12 patients with unsuccessful attempted reperfusion (group 3). Blood samples were taken every 15 min, and coronary angiography was performed every 5 to 8 min until 60 min after reperfusion (groups 1 and 2) or after the initiation of treatment (group 3). We calculated the increase in troponin T (delta troponin T) and CK-MB (delta CK-MB) 60 min after treatment was initiated and 60 min after reperfusion in groups 1 and 2.

RESULTS

Mean (+/- SD) delta troponin T and delta CK-MB levels were 9.35 +/- 7.83 ng/ml and 125 +/- 83 mU/ml in group 1 and 3.23 +/- 3.08 ng/ml and 130 +/- 137 mU/ml in group 2, respectively, 60 min after treatment and were 10.1 +/- 8.35 ng/ml and 131 +/- 84 mU/ml in group 1 and 6.84 +/- 8.30 ng/ml and 158 +/- 146 mU/ml in group 2, respectively, 60 min after reperfusion. These values were significantly higher than those 60 min after treatment in group 3: 0.16 +/- 0.19 ng/ml and 10 +/- 9 mU/ml, respectively. The predictive accuracy for detecting reperfusion using a threshold value of 0.50 ng/ml of delta troponin T and 25 mU/ml of delta CK-MB was 100% in group 1 and 92% in group 2 60 min after treatment, respectively. There was significant correlation between delta troponin T and delta CK-MB.

CONCLUSIONS

Serial measurements of cardiac troponin T as well as of CK-MB are useful for early assessment of reperfusion therapy.

Cardiac troponin I. A marker with high specificity for cardiac injury

BACKGROUND

Levels of MBCK can be increased in patients with skeletal muscle injury or renal failure in the absence of myocardial injury, causing diagnostic confusion. This study was designed to determine whether measurement of cardiac troponin I (cTnI), a myocardial regulatory protein with comparable sensitivity to MBCK, has sufficient specificity to clarify the etiology of MBCK elevations in patients with acute or chronic skeletal muscle disease or renal failure.

METHODS AND RESULTS

Of the patients (n = 215) studied, 37 had acute skeletal muscle injury, 10 had chronic muscle disease, nine were marathon runners, and 159 were chronic dialysis patients. Patients were evaluated clinically, by ECG, and by two-dimensional echocardiography. Total creatine kinase (normal, < 170 IU/L) was determined spectrophotometrically, and cTnI (normal, < 3.1 ng/mL) and MBCK (normal, < 6.7 ng/mL) were determined with specific monoclonal antibodies. Values above the upper reference limit were considered "elevated." Elevations of total creatine kinase were common, and elevations of MBCK occurred in 59% of patients with acute muscle injury, 78% of patients with chronic muscle disease and marathon runners, and 3.8% of patients with chronic renal failure. Some of the patients were critically ill; five patients were found to have had myocardial infarctions and one had a myocardial contusion. cTnI was elevated only in these patients.

CONCLUSIONS

Elevations of cTnI are highly specific for myocardial injury. Use of cTnI should facilitate distinguishing whether elevations of MBCK are due to myocardial or skeletal muscle injury.

New application of myocardial antimyosin scintigraphy: diagnosis of myocardial disease in polymyositis

Heart disease is a rare but important complication of polymyositis. Diagnosis of myocardial disease is usually based on non-specific clinical, electrocardiographic, and echocardiographic data. This paper reports a case of polymyositis with myocardial disease diagnosed by myocardial imaging with radiolabelled antibody to myosin, a specific marker of the necrotic myocardial fibre.

Polymyositis: a case history approach to the differential diagnosis and treatment

A wide range of conditions can mimic polymyositis. Thus, diagnosing this condition can be a challenge. Although no single criterion is diagnostic of polymyositis, the following criteria have been proposed and widely used: (1) symmetric proximal muscle weakness; (2) characteristic violaceous rash on the hands, elbows, and knees; (3) increased muscle enzymes in the serum; (4) characteristic electromyographic findings (insertional activity, fibrillation potentials, motor unit potentials of increased frequency and decreased duration, and normal conduction velocity in nerves); and (5) muscle biopsy specimen with characteristic inflammatory and myopathic changes. Although polymyositis primarily involves muscle, up to 20% of patients may have extramuscular problems. The main treatment for polymyositis is high-dose corticosteroids. In corticosteroid-resistant patients, methotrexate is often effective. In this report, case histories are presented to highlight the usefulness and the limitations of the common diagnostic criteria for polymyositis.

Dermatomyositis as a systemic disease

Dermatomyositis is a classic example of a disease that has both cutaneous and systemic manifestations. The skin and muscle disease are described as well as the possible systemic manifestations including overlap syndromes, joint symptoms, pulmonary disease, and other internal organ involvement. The association with pregnancy is also discussed.

Polymyositis-dermatomyositis: a clinical review

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Dermatomyositis

Dermatomyositis and polymyositis are related disorders of unknown cause in which immunologic changes may be important. They sometimes overlap with other collagen vascular diseases, and not infrequently are associated with malignancy. The clinical features of the adult and juvenile forms of the disorder and the visceral manifestations of DM-PM are outlined, along with enzymatic, electromyographic, and histologic aids to diagnosis. While the cutaneous lesions often are resistant to treatment, systemic involvement may respond to corticosteroids or to immunosuppressive drugs. Treatment definitely alters the prognosis in cases not associated with malignancy.

Creatine phosphokinase MB and lactate dehydrogenase isoenzyme 1 in polymyositis

Serious cardiac abnormalities and asymptomatic hyperkinetic heart function are frequently seen in patients with polymyositis/dermatomyositis (PM). The cardiac manifestations may be secondary to myocardial inflammation, replacement fibrosis, or alterations in the peripheral circulation. The significance of determinations of cardiospecific isoenzymes in the evaluation of myocardial manifestations in PM has not yet been established. We report on 2 patients with firm evidence of severe myocardial involvement. Nevertheless, the serum levels of creatine phosphokinase MB (CPK MB) and lactated dehydrogenase isoenzyme 1 (LDH1) were found normal. This finding casts doubt on the reliability of cardiospecific isoenzymes for the identification of inflammatory myocardial involvement in patients with PM.

Blunt cardiac trauma

The diagnosis of blunt cardiac injury is often difficult to make because of the multiple associated injuries, the lack of specific physical findings, and the lack of sensitivity and specificity of the electrocardiograms and enzyme changes. The two-dimensional echocardiogram and the monitoring of filling pressures and cardiac indexes by pulmonary artery catheterization have an advantage over the electrocardiogram, CPK isoenzymes and technetium pyrophosphate scans because both anatomic and functional data are obtained, data are rapidly available, and the tests can be used repeatedly at the bedside.

The enzymology of skeletal muscle disorders

In myopathic disorders, abnormal serum enzyme activities are seen primarily in diseases of skeletal muscle where the condition involves the muscle fibers themselves. In denervation myopathies, serum enzyme activities are usually normal. The most dramatic increases of serum enzymes, particularly creatine kinase, are found in the dystrophic diseases, particularly Duchenne dystrophy. A review is given here of the many causes of abnormal serum enzyme activities where the source of enzymes is believed to be skeletal muscle. These include the dystrophies, various types of trauma, exercise, drug- and poison-induced causes including alcohol, malignant hyperthermia, inflammatory diseases, and miscellaneous causes. Tissue and serum activities are summarized for the commonly performed serum enzymes, i.e., CK, LD, AST, and aldolase. An extensive tabular and current description of the various types of dystrophies is given along with serum CK and pyruvate kinase activities.

CK-MB isoenzyme in patients with polymyositis

Total serum creatine kinase and isoenzyme levels were studied in five patients with polymyositis. In all five patients, CK-MB isoenzyme was demonstrated by the column chromatography and electrophoretic method, although there was no evidence of myocardial infarction. The persistent elevation of CK-MB in patients with polymyositis is in contrast to the usual transient increase in myocardial infarction. Serial CK-MB isoenzyme quantitation can be used to distinguish myocardial infarction from polymyositis. CK-MB is a more sensitive indicator than AST and LDH as a monitoring device, but offers no advantage over total CK activity.