From the Guidelines
To evaluate hair loss beyond thyroid issues, I recommend comprehensive blood tests including complete blood count (CBC), ferritin, vitamin D, zinc, vitamin B12, and sex hormones (testosterone, DHT, estrogen, and DHEA-S) as the most critical initial step. These tests are essential for identifying common causes of hair loss, including nutritional deficiencies, hormonal imbalances, autoimmune conditions, and inflammatory disorders.
Key Laboratory Tests
- Complete Blood Count (CBC) to rule out underlying infections or blood disorders
- Ferritin to assess iron stores, as iron deficiency can cause hair loss even without anemia 1
- Vitamin D, as its deficiency has been linked to hair loss, particularly in autoimmune conditions like alopecia areata 1
- Zinc, given its importance in hair growth and the potential for deficiency, especially after certain surgical procedures or with specific dietary habits 1
- Vitamin B12, as its deficiency can lead to hair loss among other neurological and hematological issues
- Sex hormones (testosterone, DHT, estrogen, and DHEA-S) to evaluate hormonal imbalances that could contribute to pattern hair loss or other forms of hair loss
Additional Diagnostic Considerations
- Inflammatory markers like CRP and ESR to assess for underlying inflammatory conditions
- Autoimmune indicators such as ANA and specific antibodies for conditions like lupus or alopecia areata to identify autoimmune causes of hair loss
- A scalp biopsy may be necessary in some cases to determine the specific type of hair loss, especially when the diagnosis is unclear or when considering certain treatments
It's crucial to work with a dermatologist or endocrinologist who specializes in hair disorders to interpret these results properly and develop an appropriate treatment plan based on the underlying cause of the hair loss. The selection of these tests is guided by the most recent and highest quality evidence available, prioritizing the patient's morbidity, mortality, and quality of life outcomes.
From the Research
Laboratory Tests for Hair Loss
To investigate the cause of hair loss, excluding thyroid dysfunction, the following laboratory tests are recommended:
- Serum ferritin levels: Low serum ferritin levels have been associated with hair loss, particularly in patients with diffuse hair loss 2
- Vitamin D levels: Low vitamin D levels have also been linked to hair loss, and evaluating and supplementing vitamin D levels may be necessary prior to treatment 2
- Iron deficiency tests: Iron deficiency is a common nutritional deficiency that may be related to hair loss, and tests such as hemoglobin concentration, serum ferritin concentration, and erythrocyte zinc protoporphyrin concentration may be used to diagnose iron deficiency 3
- Other tests: Depending on the patient's medical history and physical examination, other tests such as complete blood count, electrolyte panel, and liver function tests may be ordered to rule out underlying systemic diseases that may be causing hair loss 4, 5
Key Considerations
When ordering laboratory tests for hair loss, it is essential to consider the following:
- A thorough medical history and physical examination are crucial in determining the underlying cause of hair loss 4, 5
- Laboratory tests should be used judiciously and in a cost-effective manner to avoid unnecessary testing 4
- The diagnosis and treatment of hair loss should be individualized based on the patient's specific condition and medical history 5