From the Guidelines
For a 20-year-old female with fatigue, I recommend starting with a comprehensive history, physical examination, and targeted laboratory testing, as the most recent and highest quality study suggests that a thorough evaluation is essential to identify the underlying cause of fatigue 1.
Initial Evaluation
The initial evaluation should include a focused fatigue history, including onset, pattern, duration, and associated or alleviating factors, as well as an assessment of disease status and treatable contributing factors such as comorbidities, medications, and lifestyle factors 1.
- Initial labs should include:
- Complete blood count (CBC)
- Comprehensive metabolic panel (CMP)
- Thyroid-stimulating hormone (TSH)
- Iron studies (ferritin, iron, TIBC)
- Vitamin B12
- Vitamin D
- Urinalysis
Additional Testing
Additional testing based on clinical suspicion may include:
- Inflammatory markers (ESR, CRP)
- Celiac disease screening
- Pregnancy test
- Mental health screening for depression and anxiety using standardized tools like PHQ-9 or GAD-7 1
- Sleep quality assessment, and if sleep disorders are suspected, a sleep study may be warranted
Treatment
Treatment should target the underlying cause, whether it's iron supplementation (typically ferrous sulfate 325mg daily), thyroid hormone replacement, vitamin supplementation, or mental health interventions.
- If no organic cause is identified after thorough evaluation, consider chronic fatigue syndrome, particularly if symptoms persist beyond six months with post-exertional malaise and unrefreshing sleep.
Referral
Referral to a physical therapist or exercise specialist may be beneficial for patients with severe fatigue interfering with function, as suggested by the American Society of Clinical Oncology clinical practice guideline adaptation 1.
From the Research
Fatigue Workup for a 20-Year-Old Female
Initial Evaluation
- A thorough history and physical examination are essential in the initial evaluation of fatigue in a 20-year-old female 2.
- A complete blood cell count (CBC) is a crucial test in the initial evaluation, as it provides important clues to the classification and cause of anemia 2.
Laboratory Tests
- The full blood count is the first-line laboratory test for patients suspected of being anemic, and results may suggest the anemia is caused by a nutritional deficiency of B12, folate, or iron 3.
- Supplemental tests may include a peripheral blood smear, reticulocyte count, iron panel, and levels of vitamin B12, folate, lactate dehydrogenase, haptoglobin, and bilirubin 2.
- Laboratory measurement of the concentration in blood of iron, vitamin B12, and folate is useful in the differential diagnosis of anemic patients 3.
Vitamin B12 and Iron Deficiencies
- Vitamin B12 and iron deficiencies are common problems that can cause non-specific symptoms, including fatigue 4.
- A study found that treatment of iron deficiency anemia with pharmacological iron increased serum vitamin B12 and folate levels in young adult women 5.
- Another study found that low vitamin B12 levels were present in 17.8% of patients with iron deficiency anemia, and vitamin B12 deficiency was demonstrated in many patients with low vitamin B12 and iron deficiency anemia 6.
Diagnostic Approach
- A diagnostic model based on age and homocysteine assessment can be used to differentiate iron deficiency anemia from combined deficiency of vitamin B12 and iron 6.
- The model suggests that serum vitamin B12 should be evaluated in patients with iron deficiency anemia over 60 years old, but this may not be directly applicable to a 20-year-old female 6.