From the Research
The answer is D. Liver Function Tests (LFT) are not important in making a diagnosis of dermatomyositis/polymyositis. The diagnosis of these inflammatory myopathies relies primarily on a combination of clinical features, muscle enzyme levels (particularly creatine kinase), muscle biopsy findings, and electromyography results, as highlighted in studies such as 1. Creatine kinase is typically elevated in active disease and serves as a marker of muscle damage. Muscle biopsy is considered the gold standard for diagnosis, revealing characteristic inflammatory infiltrates and muscle fiber degeneration, as noted in 2 and 3. Electromyography demonstrates myopathic changes with spontaneous fibrillations and positive sharp waves. While cardiac involvement can occur in these conditions, making ECG relevant in some cases, liver function tests do not play a significant role in establishing the diagnosis. LFTs may be abnormal in some patients due to medication effects or rarely from myositis-associated liver involvement, but they are not part of the core diagnostic criteria for dermatomyositis or polymyositis, a point emphasized by the most recent and highest quality study 1. Key diagnostic factors include:
- Clinical presentation
- Elevated creatine kinase levels
- Muscle biopsy findings
- Electromyography results
- Presence of specific autoantibodies, as discussed in 4 and 1. In contrast, liver function tests are not a critical component of the diagnostic process for dermatomyositis or polymyositis, as they do not directly reflect the pathology of these conditions, which primarily affect muscle tissue and, in the case of dermatomyositis, the skin.