What blood tests are used to investigate alopecia (hair loss)?

From the Guidelines

Blood tests for investigating hair loss should include a complete blood count (CBC), thyroid function tests (TSH, T3, T4), iron studies (ferritin, iron, total iron binding capacity), vitamin D levels, and hormone panels, as these tests can help identify underlying causes of hair loss and guide treatment approaches. When investigating hair loss, it is essential to consider the patient's symptoms, medical history, and pattern of hair loss.

• A complete blood count (CBC) can help identify underlying conditions such as anemia or infection.
• Thyroid function tests (TSH, T3, T4) can help diagnose thyroid disorders, which are common causes of hair loss 1.
• Iron studies (ferritin, iron, total iron binding capacity) can help identify iron deficiency, which is a common nutritional deficiency that can contribute to hair loss, although the evidence for its role in hair loss is mixed 1.
• Vitamin D levels can help identify vitamin D deficiency, which has been linked to hair loss, particularly in patients with alopecia areata 1.
• Hormone panels can help diagnose hormonal imbalances, such as androgenetic alopecia or polycystic ovary syndrome, which can contribute to hair loss. Additional tests may include zinc levels, vitamin B12, folate, and inflammatory markers like ESR or CRP. These tests can help identify underlying causes of hair loss, such as nutritional deficiencies, thyroid disorders, hormonal imbalances, or autoimmune conditions. Results from these tests can guide treatment approaches, which may include addressing specific deficiencies, treating underlying conditions, or implementing targeted hair loss therapies. Early testing is beneficial as addressing underlying causes promptly can lead to better outcomes in hair regrowth. It is essential to prioritize the patient's symptoms, medical history, and pattern of hair loss when selecting blood tests to investigate hair loss. By doing so, healthcare providers can provide personalized care and improve outcomes for patients with hair loss.

From the Research

Blood Tests for Hair Loss Investigation

The following blood tests are recommended to investigate hair loss:

• Complete blood count (CBC) 2
• Ferritin 2
• Thyroid stimulating hormone (TSH) 2
• Vitamin D 25OH 2 These tests can help identify underlying conditions that may be contributing to hair loss, such as anemia, thyroid dysfunction, or nutrient deficiencies.

Rationale for Blood Tests

The rationale for these blood tests is to rule out underlying medical conditions that may be causing hair loss. For example:

• A complete blood count (CBC) can help diagnose anemia, which can cause hair loss 3
• Ferritin levels can help diagnose iron deficiency, which can contribute to hair loss
• TSH levels can help diagnose thyroid dysfunction, which can cause hair loss 4
• Vitamin D 25OH levels can help diagnose vitamin D deficiency, which can contribute to hair loss

Additional Tests

In some cases, additional tests may be necessary to investigate hair loss, such as:

• Reticulocyte count to screen for hemolysis or blood loss 3
• Molecular testing to aid in the diagnosis of anemia 3
• Bone marrow examination to diagnose certain types of anemia 3 These tests can help provide a more comprehensive understanding of the underlying causes of hair loss. 5, 2, 6