What is the diagnostic workup for a disease?

From the Guidelines

The diagnostic workup for a disease should include a comprehensive evaluation of rheumatologic and neurologic history, physical examination, and laboratory tests, such as blood testing to evaluate muscle inflammation, including CK, transaminases, lactate dehydrogenase, and aldolase, as well as troponin and inflammatory markers like ESR and CRP 1. The workup should start with a complete rheumatologic and neurologic history regarding differential diagnosis, including muscle strength and examination of the skin for findings suggestive of dermatomyositis.

• A thorough physical examination is necessary, including rheumatologic and neurologic examination, to identify any preexisting conditions that can cause similar symptoms.
• Laboratory tests should include:
  • Blood testing to evaluate muscle inflammation, such as CK, transaminases (AST, ALT), lactate dehydrogenase (LDH), and aldolase
  • Troponin to evaluate myocardial involvement
  • Inflammatory markers (ESR and CRP)
  • Other cardiac testing, such as echocardiogram, as needed
• Additional tests, such as electromyography (EMG), imaging (MRI), and/or biopsy, should be considered on an individual basis when diagnosis is uncertain and overlap with neurologic syndromes, such as myasthenia gravis, is suspected 1.
• Paraneoplastic autoantibody testing for myositis and neurologic conditions, such as myasthenia gravis, should also be considered. The goal of this comprehensive workup is to identify the underlying cause of the disease and to monitor the patient's condition, including CK, ESR, and CRP levels, to guide treatment and management decisions 1.

From the Research

Diagnostic Workup for a Disease

The diagnostic workup for a disease typically involves a combination of clinical history, physical exam, and laboratory tests.

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are widely used laboratory markers of systemic inflammation 2, 3, 4, 5.
• These tests should be used only in combination with clinical history and physical exam for diagnosis and monitoring of pathological conditions 2.
• ESR and CRP lack sensitivity or specificity, and their results should be interpreted in the context of the patient's clinical presentation 2, 3, 4.
• The clinical application of these tests in diagnosis is best applied to conditions in which there is high or low clinical probability of disease 2.
• Discrepancies between ESR and CRP measurements can occur, and may be due to various physiological factors, including noninfectious conditions and resolution of inflammation 2, 4.

Laboratory Tests

• ESR is an indirect measure of fibrinogen and has a longer half-life than CRP, making it helpful in monitoring chronic inflammatory conditions 3.
• CRP is more useful in diagnosis and monitoring responses to therapy in acute inflammatory conditions, such as acute infections 3.
• Many factors can result in falsely high or low ESR and CRP levels, and it is essential to consider these factors when interpreting test results 3, 4.

Clinical Practice

• Joint measurement of ESR and CRP may not be warranted in hospital practice, as the agreement between the two markers is poor 4.
• When an inflammatory disorder is suspected, priority should be given to CRP 4.
• A thorough understanding of the characteristics and limitations of each inflammatory indicator is crucial in clinical practice 5.