What are the likely causes and initial work‑up for hair loss and light‑headedness in a 20‑year‑old?

Hair Loss and Lightheadedness in a 20-Year-Old

In a 20-year-old presenting with both hair loss and lightheadedness, you must first rule out systemic causes—particularly iron deficiency anemia, thyroid disease, and nutritional deficiencies—because these conditions directly cause both symptoms and require specific treatment to prevent progression. 1, 2, 3

Initial Diagnostic Approach

History and Physical Examination

Pattern of hair loss:

• Discrete patches with "exclamation-mark" hairs (short broken hairs at margins) indicate alopecia areata 4, 1, 5
• Diffuse thinning over the central scalp with preserved frontal hairline suggests androgenetic alopecia 1, 5
• Sudden diffuse shedding points toward telogen effluvium, often triggered by stress, illness, or nutritional deficiency 3, 6, 7

Scalp examination:

• Normal-appearing skin with patches favors alopecia areata 4
• Inflammation or scaling requires fungal culture to exclude tinea capitis 4, 1
• Nail changes (pitting, ridging) occur in ~10% of alopecia areata patients 4, 1

Lightheadedness assessment:

• Orthostatic symptoms, fatigue, and pallor suggest anemia 2
• Cold intolerance, weight changes, and menstrual irregularities point to thyroid disease 1, 8, 3
• Recent stressors, rapid weight loss, or restrictive eating raise concern for nutritional deficiencies 1, 6

Mandatory Laboratory Testing

Because lightheadedness accompanies the hair loss, you cannot rely on clinical diagnosis alone—targeted labs are essential:

• Complete blood count with hemoglobin to detect anemia 1, 2
• Serum ferritin (optimal ≥60 ng/mL for hair growth; iron deficiency is the most common nutritional deficiency worldwide and causes both hair loss and lightheadedness) 1, 2
• TSH and free T4 to rule out thyroid disease, which commonly causes both symptoms 1, 8, 3
• Vitamin D level (<20 ng/mL is deficient; 70% of alopecia areata patients are deficient vs. 25% of controls) 1
• Serum zinc (tends to be lower in alopecia areata patients) 1

Additional testing only if clinically indicated:

• Fungal culture if scalp shows inflammation or scaling 4, 1
• Lupus serology if systemic features (joint pain, photosensitivity, facial rash) are present 4, 1
• Total testosterone, free testosterone, and SHBG only if signs of androgen excess (acne, hirsutism, irregular periods) 1, 5

Diagnostic Algorithm

Step 1: Examine the scalp with dermoscopy if available

• Yellow dots + exclamation-mark hairs = alopecia areata (no biopsy needed) 1, 5
• Diffuse thinning without inflammation = likely telogen effluvium or androgenetic alopecia 1, 7
• Inflammation/scaling = obtain fungal culture before proceeding 4, 1

Step 2: Order the mandatory lab panel above (CBC, ferritin, TSH/free T4, vitamin D, zinc) 1, 2, 3

Step 3: Interpret results and treat underlying causes

• Iron deficiency (ferritin <60 ng/mL): supplement with oral iron 1, 2
• Vitamin D deficiency (<20 ng/mL): supplement per standard guidelines 1
• Hypothyroidism (high TSH, low free T4): initiate thyroid replacement 1, 8
• Zinc deficiency: supplement appropriately 1

Management Based on Hair Loss Pattern

Limited Patchy Alopecia Areata (≤5 patches, each ≤3 cm)

Watchful waiting is the first-line approach because 34–50% of patients experience spontaneous regrowth within one year without any treatment. 4, 1, 5

• Counsel that visible regrowth is unlikely within the first 3 months after a new patch appears 1, 5
• No treatment alters the long-term course of alopecia areata, though some can induce temporary regrowth 1, 5

If treatment is desired:

• Intralesional triamcinolone acetonide 5–10 mg/mL (0.05–0.1 mL per injection) monthly achieves full regrowth in ~62% of patients (Strength of recommendation B, Quality III) 1, 5

Extensive Alopecia Areata (>50% scalp involvement)

• Contact immunotherapy with diphenylcyclopropenone (DPCP) achieves response in <50% of appropriately selected patients and requires multiple clinic visits over months (Strength of recommendation B, Quality II-ii) 1, 5
• Wigs provide immediate cosmetic benefit and are often the most practical solution for extensive, longstanding disease 1, 5

Telogen Effluvium

• Remove the precipitating trigger (stress, nutritional deficiency, illness) 3, 6, 7
• Spontaneous remission occurs in up to 80% of cases with short duration (<1 year) once the trigger is removed 1, 6, 7
• Correct any identified nutritional deficiencies 1, 2, 3

Androgenetic Alopecia

• Topical minoxidil 2% solution twice daily is first-line for women (arrests progression rather than stimulates regrowth) 1, 3, 7

Critical Pitfalls to Avoid

Do not dismiss lightheadedness as unrelated to hair loss—the combination strongly suggests a systemic cause (anemia, thyroid disease, nutritional deficiency) that requires specific treatment. 2, 8, 3

Do not order extensive autoimmune panels for straightforward alopecia areata—the modest increase in autoimmune disease prevalence does not justify routine screening. 4, 1, 5

Do not confuse trichotillomania with alopecia areata—trichotillomania shows broken hairs that remain firmly anchored in anagen, whereas alopecia areata displays exclamation-mark hairs. 4, 1, 5

Do not use potent topical corticosteroids for alopecia areata—they lack convincing efficacy evidence. 1, 5

Do not prescribe systemic corticosteroids or PUVA for alopecia areata—they have potentially serious adverse effects and insufficient efficacy evidence. 1, 5

Psychological Considerations

Hair loss can have a profound psychological effect on young adults, affecting self-esteem, work productivity, and quality of life. 1, 5, 3

• Screen for anxiety and depression, especially if the patient becomes withdrawn or experiences social difficulties 1, 5
• Provide realistic expectations about treatment timelines and outcomes 3, 7
• Consider referral to mental health services if significant psychological distress is present 1, 5

When to Refer to Dermatology

• Diagnosis remains uncertain despite clinical and dermoscopic evaluation 1, 5
• Extensive alopecia areata requiring contact immunotherapy 1, 5
• Suspected scarring alopecia (requires early biopsy to prevent permanent follicular destruction) 9
• Treatment-resistant cases 1, 5