From the Guidelines
To evaluate female pattern hair loss (FPHL) in women, I recommend a comprehensive laboratory workup including complete blood count (CBC), thyroid function tests (TSH, free T3, free T4), iron studies (ferritin, serum iron, total iron binding capacity), vitamin D level, and sex hormone panel (testosterone, DHEAS, androstenedione). Additional tests should include fasting blood glucose, HbA1c, and prolactin levels, as well as testing for polycystic ovary syndrome (PCOS) with luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels if signs of androgen excess are present 1. These tests help identify common causes of female hair loss such as iron deficiency, thyroid disorders, hormonal imbalances, and nutritional deficiencies. Some studies suggest that zinc and micronutrient deficiencies may also play a role in hair loss, but the evidence is not as strong 1. It's also important to consider autoimmune markers like antinuclear antibodies (ANA) if autoimmune-related hair loss is suspected, as well as vitamin B12 and folate levels 1. These laboratory tests should complement a thorough clinical history and physical examination, as female hair loss often results from multiple contributing factors that require a systematic approach to diagnosis and treatment. Key points to consider when evaluating FPHL include:
- Iron deficiency is a common cause of hair loss, and serum ferritin levels can help identify this condition 1
- Thyroid disorders, such as hypothyroidism, can also cause hair loss, and thyroid function tests can help diagnose this condition 1
- Hormonal imbalances, such as those seen in PCOS, can contribute to hair loss, and sex hormone panels can help identify these imbalances 1
- Nutritional deficiencies, such as vitamin D deficiency, can also contribute to hair loss, and vitamin D levels should be checked 1
From the Research
Laboratory Tests for Female Pattern Hair Loss (FPHL)
To evaluate FPHL in women, several laboratory tests are indicated, including:
- Complete blood count and routine urine examination 2
- Serum ferritin concentration to check for iron deficiency 3, 2, 4, 5
- Thyroid function tests (T3, T4, and TSH) to check for thyroid hormone disorders 2, 5
- Vitamin D levels, as low levels have been associated with hair loss 5
- Hemoglobin concentration to screen for iron deficiency anemia 3
Rationale for Laboratory Tests
These laboratory tests are necessary to rule out underlying conditions that may be contributing to hair loss, such as:
- Iron deficiency anemia, which is common in premenopausal women due to menstrual blood loss 3
- Thyroid hormone disorders, which can cause hair loss 2, 5
- Vitamin D deficiency, which has been linked to hair loss 5
Limitations of Laboratory Tests
While these laboratory tests can help identify underlying conditions, they may not always be abnormal in women with FPHL. For example, one study found that hormone levels, including sex hormones and thyroid hormones, were not significantly abnormal in women with FPHL 6. Therefore, a thorough clinical evaluation and medical history are also necessary to diagnose and manage FPHL.