What is the appropriate next step in evaluating and managing a patient who reports increased hair loss, denies weight loss, has normal laboratory studies, and no evidence of thyroid disease?

Evaluation and Management of Increased Hair Loss with Normal Labs

The next step is to perform a thorough scalp examination to determine the pattern of hair loss, followed by androgen testing (total and free testosterone using LC/MS), and consider checking ferritin, vitamin D, and zinc levels, even though initial labs were "normal." 1

Clinical Assessment Priority

The diagnosis of female pattern hair loss (FPHL) is primarily clinical and requires:

• Detailed scalp examination to identify the pattern: Look specifically for centrifugal expansion in the mid-scalp or a frontal accentuation/"Christmas tree" pattern, which are the two typical presentations of FPHL 1
• Hair pull test to assess active shedding
• Consider dermatoscopic examination (trichoscopy) or scalp biopsy if the diagnosis remains unclear after clinical assessment 1

Critical Pitfall to Avoid

When you say "labs are normal," this likely means standard thyroid function was checked. However, the guideline explicitly states that assessment of androgen excess is mandatory in all patients with FPHL, even when there are no other signs of hyperandrogenism 1. Most women with FPHL actually have normal androgen levels, but this testing is still required 1.

Required Laboratory Workup

Mandatory testing:

• Total testosterone using high-quality assay (preferably LC/MS)
• Free testosterone (via equilibrium dialysis, ultracentrifugation, or estimated using SHBG) 1

Strongly recommended additional testing (even if "normal" labs were already done):

• Ferritin - Target level ≥70 ng/mL for optimal hair growth, not just the standard "normal" range of >15 ng/mL 1
• Vitamin D (25-hydroxyvitamin D) - 62% of FPHL patients have low levels 1
• Zinc levels - 15% of FPHL patients are deficient 1
• Prolactin 1

Important Nuance on "Normal" Labs

The evidence reveals a critical distinction: standard reference ranges for ferritin (<15 ng/mL defines deficiency) are insufficient for hair health. Studies show that ferritin levels <70 ng/mL may impair hair regrowth, even though this falls within the "normal" laboratory range 1. This is why you need to recheck or review the actual ferritin value, not just accept "normal."

Treatment Algorithm

Step 1: First-line treatment for all patients

• Topical minoxidil 5% (foam or solution) - This is the only treatment with sufficient evidence and should be started regardless of androgen levels 1
• Counsel patient about expected 2-8 week initial shedding phase (telogen hairs preparing for new anagen growth) 1
• Emphasize need for at least 12 months of continuous use for optimal results 1

Step 2: Add systemic therapy if:

• Severe hair loss is present, OR
• Hyperandrogenism is confirmed on testing 1
• In these cases, add 5α-reductase inhibitors or antiandrogens 1

Step 3: Address nutritional deficiencies if identified

• Though the evidence for supplementation improving hair growth is mixed and not well-controlled 1, correcting documented deficiencies (ferritin <70 ng/mL, low vitamin D, low zinc) is reasonable and may support hair regrowth 1

Key Clinical Points

• Isolated FPHL with normal androgen levels should NOT be considered a sign of hyperandrogenism 1
• The relationship between iron deficiency and FPHL remains uncertain in the literature, with conflicting studies 1, but checking ferritin with the higher threshold (70 ng/mL) is still recommended
• Quality of life impact is significant - patients with hair loss have higher rates of anxiety and depression 2, so taking their concerns seriously and providing clear management plans is essential