What is the workup for fatigue (loss of energy)?

From the Guidelines

A comprehensive workup for fatigue should begin with a thorough medical history and physical examination to identify potential causes, as recommended by the most recent guidelines 1. The initial step in evaluating fatigue is to perform a focused fatigue history, including onset, pattern, and duration, as well as associated or alleviating factors 1. This should be followed by an evaluation of disease status, including risk of recurrence and review of systems to determine if other symptoms substantiate suspicion for recurrence 1. The assessment should also include evaluating treatable contributing factors, such as comorbidities, medications, alcohol/substance abuse, nutritional issues, decreased functional status, and deconditioning/decreased activity level 1. Initial laboratory tests should include complete blood count (CBC), comprehensive metabolic panel, thyroid function tests (TSH, free T4), inflammatory markers (ESR, CRP), and ferritin levels to check for anemia, thyroid disorders, liver or kidney dysfunction, and inflammation 1. Additional tests may include vitamin B12, folate, vitamin D levels, and hemoglobin A1C to screen for diabetes 1. If these tests are normal but fatigue persists, consider screening for sleep disorders with a sleep study, depression or anxiety with standardized questionnaires, and possibly testing for chronic infections like Epstein-Barr virus or Lyme disease in appropriate clinical contexts 1. Hormonal testing may include cortisol levels to evaluate adrenal function 1. Lifestyle factors should be assessed, including sleep quality, physical activity, nutrition, stress levels, and substance use 1. Medication review is essential as many drugs can cause fatigue as a side effect 1. This systematic approach helps identify the underlying cause of fatigue, which is crucial since fatigue is a symptom rather than a diagnosis, and effective treatment depends on addressing the specific underlying condition 1. Key points to consider in the workup for fatigue include:

• Focused fatigue history and physical examination
• Evaluation of disease status and treatable contributing factors
• Initial laboratory tests, including CBC, comprehensive metabolic panel, and thyroid function tests
• Additional tests, such as vitamin B12, folate, and hemoglobin A1C, as needed
• Screening for sleep disorders, depression, and anxiety
• Hormonal testing, including cortisol levels
• Assessment of lifestyle factors, including sleep quality, physical activity, and nutrition
• Medication review to identify potential causes of fatigue.

From the Research

Workup for Fatigue or Losing Energy

• The workup for fatigue or losing energy involves a comprehensive history and physical examination to guide the diagnosis and treatment plan 2, 3.
• Fatigue can be classified as physiologic, secondary, or chronic, and the treatment approach varies depending on the classification 2, 3.
• Physiologic fatigue can be addressed by proper sleep hygiene, a healthy diet, and balancing energy expenditure 3.
• Secondary fatigue is improved by treating the underlying condition, such as anemia, which is a common cause of fatigue 4, 2.
• Laboratory studies, such as complete blood count and iron levels, may be useful in identifying underlying causes of fatigue, but are only indicated in 5% of patients 2.
• Treatment of fatigue may include a structured plan for regular physical activity, such as walking, and cognitive behavior therapy for patients with chronic fatigue 2, 3.
• Medications, such as selective serotonin reuptake inhibitors, may be useful for improving energy in patients with depression 2.
• Vitamin deficiencies, such as vitamin B12 and magnesium, may also contribute to fatigue, especially in patients with diabetes mellitus 5.

Common Causes of Fatigue

• Anemia is a common cause of fatigue, and iron deficiency anemia is the most common type of anemia worldwide 4.
• Diabetes mellitus can also cause fatigue, and patients with diabetes may have vitamin deficiencies that contribute to fatigue 5.
• Other common causes of fatigue include lifestyle issues, physical conditions, mental disorders, and treatment side effects 2.
• Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic and potentially debilitating disorder that can cause severe fatigue 3.

Treatment Approach

• The treatment approach for fatigue depends on the underlying cause and classification of fatigue 2, 3.
• A structured plan for regular physical activity and cognitive behavior therapy may be useful for patients with chronic fatigue 2, 3.
• Medications, such as selective serotonin reuptake inhibitors, may be useful for improving energy in patients with depression 2.
• Vitamin supplements, such as vitamin B12 and magnesium, may be useful for patients with vitamin deficiencies 5.
• Patients with ME/CFS should be educated about pacing their activity to avoid triggering postexertional malaise 3.