Causes of Diffuse Hair Thinning

1. Telogen Effluvium (TE) - the most common cause

• Febrile illness (high fever, sepsis, influenza)
• Major surgery or general anesthesia
• Pregnancy / postpartum (hair sheds 2-3 months after delivery as estrogen drops)
• Rapid weight loss or crash dieting (calorie restriction <1200 kcal/day, or loss of >10 kg rapidly)
• Drugs (see below)

• Thyroid disease (both hypo- and hyperthyroidism)
• Malnutrition, protein-calorie deficiency
• Iron deficiency (though the link remains somewhat controversial)
• Zinc deficiency (especially in severe cases / acrodermatitis enteropathica)
• Systemic illness (lupus, inflammatory disease, chronic infections)
• HIV infection and syphilis (STDs)
• Aging (senile effluvium with increased telogen ratio)
• Psychological stress (controversial in the literature)

2. Anagen Effluvium

• Chemotherapy (especially alkylating agents, taxanes)
• Radiation therapy to the scalp
• Heavy metal poisoning (thallium, arsenic)
• Some immunosuppressants

3. Androgenetic Alopecia (Female Pattern Hair Loss)

• Genetic predisposition
• Androgen sensitivity of hair follicles (DHT-mediated miniaturization)
• Hormonal shifts: menopause, polycystic ovary syndrome (PCOS), stopping oral contraceptives

4. Hormonal Causes

5. Nutritional / Metabolic

• Iron deficiency (ferritin <30-70 ng/mL is often the threshold studied)
• Zinc deficiency
• Biotin deficiency (rare; more common in patients on prolonged raw egg diet or TPN)
• Vitamin D deficiency
• Protein malnutrition (kwashiorkor, crash diets, bariatric surgery)
• Selenium deficiency or excess

6. Medications (Drug-Induced Alopecia)

• Anticoagulants: heparin, warfarin
• Antithyroid drugs: propylthiouracil, carbimazole
• Retinoids: isotretinoin, acitretin
• Antidepressants: SSRIs, lithium, valproate
• Beta-blockers: propranolol, metoprolol
• Hormonal: androgens, anabolic steroids, progesterone-dominant OCP
• Cholesterol-lowering: statins (less common)
• GLP-1 receptor agonists (semaglutide, tirzepatide) - a recently recognized association

7. Systemic Diseases

• Systemic lupus erythematosus (SLE) - can cause diffuse non-scarring thinning
• Inflammatory bowel disease / malabsorption syndromes
• Chronic renal failure
• Liver disease / cirrhosis
• Diabetes mellitus
• HIV/AIDS and secondary infections
• Secondary syphilis (classically "moth-eaten" but can be diffuse)

8. Hair Treatments / Cosmetic Damage

• Excessive bleaching, chemical straightening, perming
• Heat damage reducing hair shaft integrity
• Tight styling (overlaps with traction alopecia)

Key Diagnostic Approach

1. History: timing (acute vs. chronic), drug history, family history, diet, systemic illness
2. Labs: TSH, CBC, ferritin, TIBC, zinc, vitamin D, prolactin, androgens (DHEAS, free testosterone in women), ANA, RPR
3. Trichoscopy/dermoscopy: helps distinguish TE (uniform hair calibre) from androgenetic alopecia (>20% variability in hair diameter)
4. Scalp biopsy: if diagnosis remains unclear

Normal Prolactin and Testosterone Reference Ranges

Important note: Reference ranges vary between laboratories and assay methods. Always interpret results against your specific lab's reference interval. The values below are widely accepted clinical norms.

Prolactin

• >25 ng/mL in a non-pregnant woman: investigate for hyperprolactinemia
• >100 ng/mL: suggests prolactinoma or pituitary adenoma (vs. drug-induced or hypothalamic causes which are usually <100 ng/mL)
• Prolactin 5-50x above normal: highly suggestive of a prolactin-secreting adenoma (prolactinoma)
• Tietz Textbook of Laboratory Medicine, 7th Edition

Testosterone

In Men

• Sample should be drawn in the early morning (8-10 AM) when levels peak (diurnal variation - levels drop 20-30% by afternoon)
• A single low value is not diagnostic - always repeat to confirm
• Hypogonadism is a clinical + biochemical diagnosis; a "low" number alone without symptoms is not sufficient for treatment
• Free testosterone is more useful when SHBG is abnormal (e.g., obesity, liver disease, thyroid disease)
• Textbook of Family Medicine, 9th Edition

In Women

• Women's testosterone is 10-20x lower than men's
• Elevated levels suggest PCOS, congenital adrenal hyperplasia (CAH), adrenal or ovarian tumor, or exogenous androgen use
• Levels vary slightly across the menstrual cycle

Quick Reference Summary

• Prolactin high + hair loss + irregular periods + galactorrhea → hyperprolactinemia workup (MRI pituitary)
• Testosterone low (men) + fatigue + low libido + reduced muscle mass → hypogonadism workup
• Testosterone high (women) + hair loss + acne + irregular periods → androgen excess workup (PCOS, CAH)

Diffuse Hair Loss with Normal Anti-TPO, Testosterone & Prolactin

1. TSH May Still Be Abnormal (Check TSH Directly)

• Subclinical hypothyroidism (elevated TSH, normal T4) with no anti-TPO elevation
• Non-autoimmune hypothyroidism (iodine deficiency, post-surgical, central/secondary hypothyroidism)
• Hyperthyroidism (low TSH) - often missed, also causes diffuse shedding

Anti-TPO being normal does not exclude thyroid dysfunction. TSH + free T4 must be checked independently.

2. Iron Deficiency / Low Ferritin (Most Common Identifiable Cause)

• Hair loss is typically a diffuse nonscarring alopecia
• Reported with ferritin <100 ng/mL (even without frank anemia)
• Ferritin <15 ng/mL: diagnostic of iron deficiency; ferritin <50 ng/mL should be considered abnormal in a symptomatic patient
• Iron may serve as a broader marker of nutritional status rather than being the direct causal factor alone

Key clinical point: A patient can have normal hemoglobin and CBC but still have depleted iron stores causing hair loss. Always check ferritin specifically.

3. Telogen Effluvium (TE) from a Trigger 2-4 Months Prior

4. Chronic Telogen Effluvium (CTE) - Idiopathic

• Affects middle-aged women (30-60 years), often with a history of previously very thick, long hair
• Diffuse shedding + bitemporal recession, fluctuating course
• All labs (including thyroid, iron, hormones) may be entirely normal
• Mechanism: intrinsic shortening of the anagen (growth) phase
• Diagnosis of exclusion; may respond to 5% minoxidil - Fitzpatrick's Dermatology

5. Nutritional Deficiencies (Beyond Iron)

6. Androgenetic Alopecia (AGA) in Women - Diffuse Form

• AGA can occur with normal circulating androgens due to increased follicular sensitivity to DHT (5-alpha reductase activity)
• Female pattern AGA presents as diffuse centroparietal thinning (Ludwig pattern) or Christmas-tree pattern - maintained frontal hairline distinguishes it from male AGA
• Family history is often positive
• Dermoscopy shows >20% variability in hair shaft diameter (miniaturization)

Check free testosterone and DHEAS if not done - total testosterone alone can be normal even with androgen-driven AGA. - Fitzpatrick's Dermatology

7. Drug-Induced Alopecia

• Beta-blockers (propranolol, metoprolol)
• Anticoagulants (heparin, warfarin)
• Antidepressants (SSRIs, lithium, valproate)
• Retinoids (isotretinoin, acitretin)
• Antithyroid drugs
• GLP-1 agonists (semaglutide/Ozempic - likely via rapid weight loss-induced TE)
• Captopril, enalapril, cimetidine, carbamazepine, levodopa - Andrews' Diseases of the Skin

8. Other Systemic Conditions to Exclude

Recommended Workup Summary for This Patient

The single most important extra step: check TSH and ferritin - these are the two most common, treatable, and easily missed causes when anti-TPO/testosterone/prolactin are all normal.

Treatment of Chronic Telogen Effluvium (CTE)

First - Understand What You're Treating

• CDTHL: treat and eliminate the underlying cause - hair recovers
• True idiopathic CTE: cause unknown, so management is different

Step 1 - Correct Any Identifiable Underlying Cause (CDTHL)

Iron replacement alone may not resolve the hair loss but improves overall nutritional status - Andrews' Diseases of the Skin

Step 2 - Core Management of Idiopathic CTE

A. Reassurance + Psychological Support (First-Line)

• Explain the hair cycle and the mechanism of TE to the patient
• Reassure that CTE does not lead to total baldness - long-term follow-up shows no visible reduction in hair density even after 7-8 years of continuous fluctuating loss
• Counsel that spontaneous resolution is the expected outcome
• For patients needing objective proof of recovery: periodical collection and counting of shed hairs under standardized conditions (e.g., after daily shampooing) - the patient can visually track improvement
• Address any underlying anxiety or depression, which may co-exist and worsen perceived symptoms (trichodynia is common in CTE and is often linked to anxiety)
• Fitzpatrick's Dermatology

B. Topical Minoxidil 5% (First Pharmacologic Option)

• Minoxidil 5% solution or foam applied to scalp once or twice daily
• Mechanism: prolongs anagen phase, increases follicle size, increases hair shaft diameter
• Effective in CTE - may respond to 5% formulation
• Important warning to give patients: shedding typically increases for the first 2-6 weeks after starting minoxidil (immediate telogen release mechanism) - patients must be warned or they will stop the drug thinking it is worsening things
• Results visible at 3-6 months; assess at 12 months for full effect
• Side effects: scalp irritation or contact dermatitis (more with liquid due to propylene glycol; use foam if this occurs)
• Fitzpatrick's Dermatology, Cummings Otolaryngology

C. Low-Dose Oral Minoxidil (Emerging / Off-Label)

• Used when topical minoxidil is insufficient or not tolerated
• Dose: 0.25 mg to 2.5 mg daily (women); lower doses used to minimize cardiovascular side effects
• A retrospective study of 36 women with CTE treated with oral minoxidil showed improvement in all patients at 6 or 12 months
• More rapid and extensive hair growth than topical in some patients
• Not FDA-approved for hair loss - prescribed off-label
• Must discuss cardiovascular risks before prescribing (fluid retention, pericardial effusion, reflex tachycardia)
• Common side effect: hypertrichosis (facial hair growth)
• Cummings Otolaryngology Head and Neck Surgery

Step 3 - Additional / Adjunctive Options

Step 4 - Manage Comorbid Scalp Disease

• Treat seborrheic dermatitis or scalp psoriasis if present (listed as TE triggers)
• Anti-inflammatory scalp conditions can worsen TE

Prognosis

• CTE has a favorable long-term prognosis - visible baldness does not occur
• Shedding fluctuates but does not progress to complete hair loss
• Hair density remains normal or near-normal long-term even without specific treatment
• Spontaneous resolution occurs in many patients over months to years
• The condition is distressing but not disfiguring - this message is important to convey clearly
• Fitzpatrick's Dermatology (Whiting DA, long-term follow-up)

Summary Flowchart

CTE suspected (>6 months diffuse shedding)
    ↓
Thorough investigation to exclude CDTHL causes
    ↓
Cause found? → Treat it (iron, thyroid, drugs, nutrition)
    ↓
No cause found (true idiopathic CTE)?
    ↓
1. Reassurance + counseling (mandatory)
2. Topical minoxidil 5% (first-line drug)
3. Address nutritional deficiencies
4. Low-dose oral minoxidil if inadequate response (off-label)
5. Consider PRP, LLLT as adjuncts
6. Monitor and follow up every 3-6 months

Shampoos for Telogen Effluvium

1. Ketoconazole 2% Shampoo - Best Evidence (Adjunctive)

• Most studied shampoo in the context of hair loss
• Primary action: antifungal targeting Malassezia (scalp yeast), reduces scalp inflammation
• Secondary effects: may weakly inhibit androgen activity at the scalp level (5-alpha reductase inhibition locally)
• Studies show 18% increase in hair density and 7% increase in shaft diameter over 6 months in alopecia patients
• Reduces scalp inflammation that can co-exist with and worsen TE
• How to use: 2-3 times per week, leave on scalp for 3-5 minutes before rinsing
• Can be drying with frequent use - follow with conditioner on lengths (not scalp)

2. Zinc Pyrithione Shampoo

• Anti-dandruff, antifungal, anti-inflammatory
• Reduces Malassezia overgrowth and scalp inflammation
• Some evidence of modest hair count improvement in AGA; useful adjunct in TE
• Gentler than ketoconazole, suitable for daily use
• Good choice if scalp is dry/sensitive

3. Caffeine Shampoo

• Caffeine penetrates the scalp and has been shown to stimulate hair follicle metabolism and prolong anagen duration in lab studies
• A study showed significant reduction in hair loss over 3 months compared to placebo
• Mechanism: inhibits phosphodiesterase, increases cAMP in follicular cells - similar pathway to minoxidil
• Important: must be left on scalp for at least 2 minutes before rinsing to allow absorption
• Particularly relevant to TE as it targets the anagen/telogen balance

4. Biotin + Keratin Fortifying Shampoos

• Strengthen the hair shaft and reduce breakage
• Do NOT treat the underlying shedding but improve appearance and reduce mechanical hair loss
• Examples: OGX Biotin & Collagen, Viviscal Gorgeous Growth
• Useful while waiting for pharmacologic treatments to take effect (3-6 months)

5. Gentle/Sulfate-Free Shampoo (General Recommendation)

• During active TE, the scalp is already shedding more; harsh sulfate-based shampoos can accelerate mechanical loss
• Use a gentle, sulfate-free shampoo for regular washing
• Wash every 2-3 days (not daily unless very oily - daily washing doesn't cause TE, but excessive manipulation does)
• Examples: Vanicream Free & Clear, CeraVe Hydrating Cleanser (scalp), Dove Dermacare

What to Avoid

Practical Shampoo Routine for TE

Bottom Line

Best 2% Ketoconazole Shampoos

Availability Note

Top 2% Ketoconazole Shampoo Brands

Which to Choose

• Nizoral 2% if available - most evidence, well-formulated
• Ketomac or Scalpe+ are excellent, cost-effective alternatives in South Asia with equivalent active ingredient concentration

How to Use (Correct Technique)

1. Wet scalp thoroughly
2. Apply shampoo directly to scalp (not hair lengths)
3. Leave on for 3-5 minutes - this contact time is essential for effect; rinsing immediately defeats the purpose
4. Rinse thoroughly
5. Use 2-3 times per week (not daily - can cause dryness)
6. Follow with a gentle conditioner on the lengths (avoid scalp)

Important Points

• Expect no dramatic hair regrowth from ketoconazole shampoo alone - it is an adjunct, not a standalone cure
• Works best when combined with topical minoxidil (the two have complementary mechanisms)
• Avoid using on chemically colored/bleached hair frequently - can slightly affect color
• If scalp becomes dry or irritated, reduce to once a week and increase moisturizing conditioner