From the Guidelines
For global scalp hair thinning, I recommend a comprehensive laboratory workup including complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid function tests (TSH, free T3, free T4), iron studies (ferritin, iron, TIBC, transferrin saturation), vitamin D level, and hormone panel (testosterone, DHT, DHEA-S, estradiol, prolactin). These tests help identify common causes of hair loss such as anemia, thyroid dysfunction, nutritional deficiencies, and hormonal imbalances. Ferritin levels should ideally be above 70 ng/mL for optimal hair growth, while vitamin D should be maintained between 50-80 ng/mL. Additional specialized tests may include zinc levels, vitamin B12, folate, and inflammatory markers like CRP and ESR if autoimmune conditions are suspected. For women, consider testing PCOS markers including LH/FSH ratio and androgen levels. Testing should be done before breakfast when possible, especially for hormone panels, to capture accurate baseline levels. Understanding these laboratory values allows for targeted treatment of underlying causes rather than just addressing symptoms, potentially leading to more effective management of hair thinning.
Key Laboratory Tests
- Complete blood count (CBC) to rule out anemia
- Comprehensive metabolic panel (CMP) to assess liver and kidney function
- Thyroid function tests (TSH, free T3, free T4) to evaluate thyroid dysfunction
- Iron studies (ferritin, iron, TIBC, transferrin saturation) to assess iron deficiency
- Vitamin D level to maintain optimal levels for hair growth
- Hormone panel (testosterone, DHT, DHEA-S, estradiol, prolactin) to evaluate hormonal imbalances
Additional Specialized Tests
- Zinc levels
- Vitamin B12
- Folate
- Inflammatory markers like CRP and ESR
- PCOS markers including LH/FSH ratio and androgen levels for women According to the most recent study 1, assessing the response to treatment in androgenetic alopecia (AGA) involves various methods, including photography, trichoscopy, hair counts, hair diameter measurement, pull test, patient self-assessment questionnaire, trichogram, and scalp biopsy. However, these methods are more relevant to evaluating treatment response rather than initial laboratory workup for global scalp hair thinning.
From the FDA Drug Label
Minoxidil topical solution 5% is for men with hair loss or thinning hair that begins on the vertex of the scalp. The FDA drug label does not answer the question about labs for global scalp hair thinning.
From the Research
Labs for Global Scalp Hair Thinning
- To diagnose hair loss, including global scalp hair thinning, laboratory tests such as a complete blood count, ferritin, thyroid stimulating hormone, and vitamin D 25OH should be ordered 2.
- Iron deficiency is a common cause of hair loss, and ferritin measurement is the most important analysis in the study of iron deficiency 3.
- A ferritin level of <30 μg/L is often used as a diagnostic cut-off for iron deficiency, but this may not be sensitive enough to detect all cases of iron deficiency 3.
- Other laboratory tests that may be useful in diagnosing iron deficiency include transferrin receptor in plasma, which increases with iron deficiency without being influenced by inflammation 3.
- A complete blood count (CBC) can also be used to diagnose iron deficiency anemia, with parameters such as red blood cell count, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, and mean corpuscular hemoglobin having higher discriminating powers for iron deficiency anemia 4.
- In patients with hair loss, it is essential to identify and treat any underlying causes of iron deficiency, such as heavy menstrual bleeding, pregnancy, or inflammatory bowel disease 5.
- Laboratory tests such as serum ferritin and transferrin saturation are required for the diagnosis and screening of iron deficiency and iron-deficiency anemia 5.