From the Guidelines
The diagnostic workup for generalized weakness should begin with a thorough history and physical examination, followed by initial laboratory tests including complete blood count, comprehensive metabolic panel, thyroid function tests, vitamin B12, vitamin D, and inflammatory markers like ESR and CRP, as recommended by the most recent guidelines 1. The workup should be systematic and guided by the pattern of weakness, associated symptoms, and risk factors to avoid unnecessary testing while identifying the underlying cause.
Key Components of the Diagnostic Workup
- Complete rheumatologic and neurologic history regarding differential diagnosis; rheumatologic and neurologic examination, including muscle strength; and examination of the skin for findings suggestive of dermatomyositis, as suggested by 1 and 1.
- Blood testing to evaluate muscle inflammation, including CK, transaminases (AST, ALT), LDH, and aldolase, as well as troponin to evaluate myocardial involvement and other cardiac testing, such as echocardiogram, as needed 1.
- Inflammatory markers (ESR and CRP) should also be evaluated, and consider EMG, imaging (MRI), and/or biopsy on an individual basis when diagnosis is uncertain and overlap with neurologic syndromes, such as myasthenia gravis, is suspected 1.
- Consider paraneoplastic autoantibody testing for myositis and neurologic conditions, such as myasthenia gravis, as recommended by 1 and 1.
Special Considerations
- In patients with suspected autoimmune conditions, order ANA, rheumatoid factor, and specific antibody tests, and consider referral to a rheumatologist or neurologist, as suggested by 1.
- In elderly patients, consider medication review as polypharmacy can contribute to weakness, and evaluate for endocrine disorders with appropriate hormone testing, including cortisol levels if adrenal insufficiency is possible.
- The approach should prioritize the patient's quality of life, morbidity, and mortality, and be guided by the most recent and highest-quality evidence, such as the 2021 update on the management of immune-related adverse events in patients treated with immune checkpoint inhibitor therapy 1.
From the Research
Diagnostic Workup for Generalized Weakness
The diagnostic workup for generalized weakness involves a comprehensive approach, including:
- History taking: A thorough patient history is fundamental for the accurate diagnosis and effective management of health conditions 2
- Physical examination: Evaluation begins with the history and physical examination, followed by diagnostic testing in some cases 3
- Diagnostic testing: The likely diagnoses for generalized weakness are based largely on the hospital setting, and most cases are not due to primary neurologic diseases 4
Key Considerations
- The differential diagnosis for generalized weakness is broad and requires careful review of the history and the key components of the patient's hospitalization 4
- Vitamin B12 deficiency is a potential cause of generalized weakness, and screening for vitamin B12 levels should be undertaken in all hypothyroid patients, irrespective of their thyroid antibody status 5
- Physical therapy may be used in patients hospitalized with a diagnosis of generalized weakness, particularly those with more severe comorbidities 6
Evaluation Process
- The evaluation process for generalized weakness involves a syndromic approach, with consideration of the problems of neurogenic respiratory muscle weakness and failure to wean from mechanical ventilation 4
- The hospital setting, such as the intensive care unit, postoperative period, medical ward, or oncologic service, can influence the likely diagnoses for generalized weakness 4