What are the recommended laboratory tests and treatment options, including supplements, for patients experiencing hair loss?

Recommended Laboratory Tests and Treatment for Hair Loss

For patients with hair loss, check serum ferritin, vitamin D, zinc, TSH, and consider testosterone/SHBG in women with signs of androgen excess; treat with topical minoxidil as first-line therapy, intralesional corticosteroids for alopecia areata patches, and supplement deficient micronutrients. 1, 2, 3

Laboratory Testing Approach

Essential Tests for All Hair Loss Patients

Check these labs to identify treatable nutritional and hormonal causes:

• Serum ferritin - Iron deficiency is the most common nutritional deficiency worldwide and a sign of chronic diffuse telogen hair loss, with lower levels found in women with alopecia areata and androgenetic alopecia 1, 2

• Vitamin D (25-OH vitamin D) - Deficiency (<20 ng/mL or <50 nmol/L) shows strong association with hair loss, with 70% of alopecia areata patients deficient versus 25% of controls, and lower levels correlate inversely with disease severity 4, 1

• Serum zinc - Zinc serves as a cofactor for multiple enzymes critical for hair follicle function, with levels tending to be lower in alopecia areata patients, particularly those with resistant disease >6 months duration 4, 1

• Thyroid stimulating hormone (TSH) - Rule out thyroid disease which can cause hair loss; if TSH is high and free T4 is low (indicating biochemical hypothyroidism), check thyroid peroxidase (TPO) antibodies 1

Additional Tests Based on Clinical Presentation

For women with signs of androgen excess (acne, hirsutism, irregular periods):

• Total testosterone or bioavailable/free testosterone levels 1
• Sex hormone binding globulin (SHBG) 1
• Consider screening for polycystic ovary syndrome (PCOS) 1
• Prolactin level if hyperprolactinemia suspected 1
• Two-hour oral glucose tolerance test if diabetes/insulin resistance suspected 1
• Fasting lipid and lipoprotein levels 1

When Laboratory Testing is NOT Needed

Most cases of alopecia areata can be diagnosed clinically without laboratory workup - investigations are unnecessary when the diagnosis is clinically evident with typical patchy hair loss, exclamation mark hairs, and dermoscopy findings (yellow dots, cadaverized hairs) 4, 1

Consider labs only when:

• Diagnosis is uncertain or presentation is atypical 4, 1
• Diffuse alopecia areata is suspected (may require biopsy) 1
• Other conditions in the differential diagnosis need exclusion 4

Specialized Testing for Specific Scenarios

• Fungal culture - When tinea capitis (scalp ringworm) is suspected 4, 1, 2
• Skin biopsy - For difficult cases, early scarring alopecia, or diffuse alopecia areata that is challenging to diagnose 4, 1
• Serology for lupus erythematosus - When systemic lupus is in the differential 4, 1
• Serology for syphilis - When secondary syphilis is suspected (presents with patchy "moth-eaten" hair loss) 4, 1

Treatment Recommendations

First-Line Topical Treatment

Minoxidil is the primary FDA-approved topical treatment:

• For men: Apply minoxidil 5% topical solution, 1 mL with dropper twice daily directly onto the scalp in the hair loss area 3
• For women: Use minoxidil 2% (minoxidil 5% is not recommended for women as studies show it works no better than 2%, and some women may grow facial hair) 3
• Timeline for results: Hair regrowth may occur at 2 months with twice daily use; some patients may need at least 4 months before seeing results 3
• Continued use is necessary to maintain hair regrowth, or hair loss will begin again 3
• Important caveat: Initial temporary increase in hair loss for up to 2 weeks is expected as old hairs shed to make way for new growth 3

Treatment for Alopecia Areata

For limited patchy alopecia areata:

• Intralesional corticosteroid injections are first-line treatment - use triamcinolone acetonide (5-10 mg/mL) injected into the upper subcutis 4, 2
• This has the strongest evidence (Strength of recommendation B, Quality of evidence III) 4

For extensive patchy alopecia areata:

• Contact immunotherapy is the best-documented treatment but is not widely available, involves multiple hospital visits over several months, and stimulates cosmetically worthwhile hair regrowth in <50% of patients 4
• This is the only treatment likely to be effective in alopecia totalis/universalis, though response rates are even lower in severe cases 4

Micronutrient Supplementation

Supplement deficient micronutrients identified on laboratory testing:

• Vitamin D supplementation - For patients with levels <20 ng/mL, though no double-blind trials have yet examined oral supplementation as a treatment strategy for alopecia areata 4, 2
• Zinc supplementation - For patients with low serum zinc levels, particularly those with alopecia areata and telogen effluvium 4, 2
• Folate supplementation - May contribute to hair health when deficient 1, 2

Important limitation: While topical vitamin D analogs (calcipotriol 0.005%) showed promise in some uncontrolled trials with 59-75% of patients experiencing hair regrowth, results have been inconsistent and most studies lacked placebo controls 4

Additional Treatment Considerations

Platelet-rich plasma (PRP) injections may be used as an adjunctive treatment to stimulate hair follicle growth 2

For women with hyperandrogenism-related hair loss, systemic antiandrogen therapy may be needed when associated with high androgen levels 5

Common Pitfalls to Avoid

• Ordering excessive laboratory tests when the diagnosis is clinically evident - alopecia areata is typically diagnosed clinically 4, 1
• Failing to consider the psychological impact - alopecia areata may cause considerable psychological and social disability warranting assessment for anxiety and depression 4, 1
• Overlooking dermoscopy as a non-invasive diagnostic tool that can provide valuable information (look for yellow dots, exclamation mark hairs, cadaverized hairs) 1
• Not recognizing that many cases are self-limited - 34-50% of alopecia areata patients recover within one year without treatment, making the tendency to spontaneous remission an important consideration in management 4, 1
• Expecting immediate results from minoxidil - patients need counseling that hair regrowth takes time (2-4 months minimum) and continued use is necessary 3