What laboratory tests are recommended for patients presenting with hair loss and fatigue?

Laboratory Tests for Hair Loss and Fatigue

For patients presenting with hair loss and fatigue, a comprehensive laboratory panel should include complete blood count, thyroid-stimulating hormone (TSH), ferritin, serum electrolytes (including calcium and magnesium), blood urea nitrogen, serum creatinine, fasting blood glucose, liver function tests, and vitamin D levels. 1, 2

Initial Laboratory Evaluation

Essential Tests:

• Complete blood count (CBC) - Evaluates for anemia, infection, and other hematologic abnormalities 3, 1
• Thyroid function tests - TSH and free T4 to assess for hypo/hyperthyroidism 1, 2
• Iron studies - Ferritin is the most sensitive marker for iron deficiency 2
• Comprehensive metabolic panel:
  • Serum electrolytes (including calcium and magnesium)
  • Blood urea nitrogen (BUN)
  • Serum creatinine
  • Fasting blood glucose
  • Liver function tests 3, 1
• Vitamin D (25OH) level 2

Additional Tests Based on Clinical Suspicion:

• Inflammatory markers (ESR, CRP) - If systemic inflammatory condition suspected
• Hormonal evaluation - Consider testing for androgens in women with pattern hair loss
• Zinc levels - Particularly in patients with poor dietary intake 1

Diagnostic Approach Based on Pattern of Hair Loss

Diffuse Hair Loss:

• Focus on systemic causes:
  • Thyroid dysfunction (both hypo- and hyperthyroidism)
  • Iron deficiency (even without anemia)
  • Nutritional deficiencies
  • Medications
  • Chronic disease

Patchy Hair Loss:

• Consider autoimmune conditions
• Evaluate for fungal infections (KOH preparation or fungal culture)
• Scalp biopsy may be necessary

Evaluation of Fatigue

When fatigue accompanies hair loss, additional considerations include:

• Screening for depression - Consider using the two-question test 3:

  • "In the last month, have you often felt dejected, sad, depressed or hopeless?"
  • "In the last month, did you experience significantly less pleasure than usual with the things you normally like to do?"

• Cancer-related fatigue screening - If cancer history present, use a numerical rating scale (NRS) with values ≥4/10 indicating moderate to severe fatigue requiring further evaluation 3

Common Pitfalls to Avoid

1. Missing subclinical thyroid disease - Even mild thyroid dysfunction can cause hair loss and fatigue
2. Overlooking iron deficiency - Ferritin levels <30 ng/mL can cause hair loss even with normal hemoglobin
3. Neglecting medication review - Many medications can cause both hair loss and fatigue
4. Incomplete evaluation - Hair loss and fatigue often have multifactorial causes requiring thorough investigation

Special Considerations

• Cancer patients - May require more extensive evaluation for cancer-related fatigue 3
• Heart failure patients - May present with fatigue and hair loss due to poor perfusion and medication side effects 3
• Chronic liver disease - Can cause both symptoms and requires specific evaluation 3

Remember that hair loss and fatigue often represent early manifestations of systemic disease, and thorough laboratory evaluation is essential for timely diagnosis and treatment of underlying conditions.