Hair Loss Causes and Diagnostic Approach

Primary Types of Hair Loss

Alopecia areata is an autoimmune condition mediated by T lymphocytes targeting hair follicles, characterized by patchy, non-scarring hair loss, and associated with other autoimmune diseases, according to the British Journal of Dermatology 1, 2
About 20% of people with alopecia areata have a family history, and it is associated with other autoimmune diseases, as reported by the British Journal of Dermatology 1, 3

Other Important Causes

Vitamin D deficiency is associated with hair loss in women, with multiple studies finding lower serum vitamin D levels in women with hair loss, as reported by the American Journal of Clinical Dermatology 4, 5
Zinc deficiency is also associated with hair loss, with serum zinc levels tend to be lower in patients with alopecia areata, according to the American Journal of Clinical Dermatology 5
Folate deficiency may contribute to hair loss, as reported by the American Journal of Clinical Dermatology 5

Diagnostic Approach

Dermoscopy can aid diagnosis of alopecia areata, looking for yellow dots, exclamation mark hairs, and cadaverized hairs, as reported by the British Journal of Dermatology 1, 2
Laboratory testing, including serum ferritin, vitamin D, zinc, and folate levels, can help diagnose nutritional deficiencies, according to the American Journal of Clinical Dermatology 5
Fungal culture and skin biopsy may be necessary in some cases, as reported by the British Journal of Dermatology 3

Hair Loss Causes and Mechanisms

Introduction to Hair Loss

Alopecia areata is an autoimmune condition mediated by T lymphocytes targeting hair follicles, according to the British Journal of Dermatology 6, 7, 8
Androgenetic alopecia (pattern hair loss) is typically related to sensitivity to dihydrotestosterone (DHT), as reported in Periodontology 2000 9

Types of Hair Loss

Trichotillomania (compulsive hair pulling) is a cause of hair loss, as noted in the British Journal of Dermatology 6
Tinea capitis (fungal infection) is another cause of hair loss, also reported in the British Journal of Dermatology 6
Telogen effluvium (stress-induced shedding) is a common cause of hair loss, as stated in the British Journal of Dermatology 6
Anagen effluvium (drug-induced) is a type of hair loss, according to the British Journal of Dermatology 6
Systemic conditions like lupus erythematosus can cause hair loss, as reported in the British Journal of Dermatology 6

Diagnosis and Advice

If a patient experiences hair loss while taking Tongkat Ali, consider other common causes of alopecia, as advised by the British Journal of Dermatology 6, 7, 8
For patients concerned about hair loss, proper diagnosis is essential to determine the specific type and cause, as recommended by the British Journal of Dermatology 6, 10

Laboratory Tests for Alopecia

Diagnostic Considerations

The British Journal of Dermatology recommends that investigations are unnecessary in most cases of alopecia areata, as the diagnosis is usually made clinically 11, 12
Laboratory tests should be considered when the diagnosis is uncertain or atypical presentation, according to the British Journal of Dermatology 11, 12
The British Journal of Dermatology suggests that laboratory tests should be considered when other conditions in the differential diagnosis need to be ruled out 12

Recommended Laboratory Tests

Fungal culture is recommended when tinea capitis is suspected, as suggested by the British Journal of Dermatology 11, 12
Skin biopsy is recommended for difficult cases, early scarring alopecia, or diffuse alopecia areata that is challenging to diagnose, according to the British Journal of Dermatology 11, 12
Serology for lupus erythematosus is recommended when systemic lupus is in the differential diagnosis, as suggested by the British Journal of Dermatology 11, 12
Serology for syphilis is recommended when secondary syphilis is suspected, according to the British Journal of Dermatology 11, 12

Differential Diagnosis to Consider

Trichotillomania, tinea capitis, early scarring alopecia, telogen effluvium, anagen effluvium, systemic lupus erythematosus, and secondary syphilis should be considered in the differential diagnosis, as suggested by the British Journal of Dermatology 11, 12

Common Pitfalls to Avoid

Ordering excessive laboratory tests when the diagnosis is clinically evident should be avoided, according to the British Journal of Dermatology 11, 12
Failing to consider the psychological impact of alopecia areata, which may warrant assessment for anxiety and depression, is a common pitfall, as suggested by the British Journal of Dermatology 11
Overlooking dermoscopy as a non-invasive diagnostic tool that can provide valuable information is a common pitfall, according to the British Journal of Dermatology 11

Diagnostic Approach to Hair Loss

Laboratory Tests for Hair Loss

The American Academy of Family Physicians recommends testing for total testosterone or bioavailable/free testosterone levels, as well as sex hormone binding globulin (SHBG) levels, in women with signs of androgen excess, such as acne, hirsutism, and irregular periods 13
The American Academy of Family Physicians suggests considering testing for polycystic ovary syndrome (PCOS) which can cause hair loss, in women with signs of androgen excess 13
The American Academy of Family Physicians recommends checking prolactin level if hyperprolactinemia is suspected, as it may contribute to hair loss 13
The American Academy of Family Physicians advises performing a two-hour oral glucose tolerance test if diabetes or insulin resistance is suspected, as these conditions may be associated with hair loss 13
The American Academy of Family Physicians recommends assessing fasting lipid and lipoprotein levels to evaluate for dyslipidemia, which may be related to hair loss 13
Thyroid stimulating hormone (TSH) levels should be checked to rule out thyroid disease, which can cause hair loss, according to the American Academy of Family Physicians 13

Laboratory Testing for Hair Loss

Recommended Laboratory Tests

Serum ferritin levels are lower in women with alopecia areata and androgenetic alopecia, with iron deficiency being the most common nutritional deficiency worldwide and a sign of chronic diffuse telogen hair loss 14
Vitamin D deficiency, defined as <20 ng/mL or <50 nmol/L, shows an inverse correlation with disease severity, with a prevalence of 70% in alopecia areata patients versus 25% in controls 15, 16
Zinc serves as a cofactor for multiple enzymes and plays a role in hair follicle function, with serum zinc levels tending to be lower in patients with alopecia areata 14
Thyroid stimulating hormone (TSH) should be checked to rule out thyroid disease, which can cause hair loss, with high TSH and low free T4 indicating biochemical hypothyroidism 17
Thyroid peroxidase (TPO) antibody testing is warranted if biochemical hypothyroidism is confirmed 17

Hair Loss Causes and Mechanisms

Autoimmune Causes

Alopecia areata is mediated by T lymphocytes attacking hair follicles, resulting in patchy, non-scarring hair loss that can affect any hair-bearing area, with approximately 20% of affected individuals having a family history, indicating genetic susceptibility, and the condition associates with other autoimmune diseases including thyroid disease, lupus, and vitiligo, and is characterized by exclamation mark hairs (short broken hairs) around expanding patches, with a prognosis that varies, where 34-50% recover within one year, but 14-25% progress to total scalp or body hair loss, and childhood onset and ophiasis pattern (scalp margin involvement) carry poorer prognoses 18
The British Journal of Dermatology recommends considering the association of alopecia areata with other autoimmune diseases, including thyroid disease, lupus, and vitiligo, in the diagnosis and management of the condition 18

Nutritional Deficiencies

Vitamin D deficiency shows strong association with hair loss, with 70% of alopecia areata patients having levels <20 ng/mL versus 25% of controls, and lower vitamin D levels correlate inversely with disease severity, and the vitamin D receptor (VDR) plays a critical role in hair follicle cycling 19
Zinc deficiency impairs hair follicle function, with serum zinc levels tending to be lower in alopecia areata patients 20

Telogen effluvium is stress-induced shedding where physiologic or emotional stressors push hair follicles prematurely into the resting (telogen) phase, and can be triggered by various factors, including illness, surgery, childbirth, severe emotional stress, rapid weight loss, and nutritional deficiencies, although the exact triggers are not always clear 18

Medication-Induced Hair Loss

Anagen effluvium occurs when medications (particularly chemotherapy) interrupt actively growing hair follicles, causing hair loss that is typically more rapid and severe than telogen effluvium, with chemotherapy being the most common cause 18

Infectious Causes

Tinea capitis (scalp ringworm) causes patchy hair loss with scalp inflammation and scaling, requires fungal culture for diagnosis, and treatment requires oral antifungal therapy, with signs that may be subtle, making diagnosis challenging 18

Physical/Mechanical Causes

Trichotillomania is compulsive hair pulling that mimics alopecia areata, distinguished by incomplete hair loss and firmly anchored broken hairs that remain in anagen phase, and may coexist with alopecia areata in some cases 18

Systemic lupus erythematosus can cause both scarring and non-scarring alopecia, and secondary syphilis presents with patchy "moth-eaten" hair loss, highlighting the importance of considering systemic diseases in the diagnosis of hair loss 18

Diagnostic Considerations

The British Journal of Dermatology recommends a clinical diagnosis of alopecia areata without laboratory workup in most cases, but laboratory testing is indicated when diagnosis is uncertain or presentation is atypical, or when diffuse alopecia areata is suspected, which may require biopsy 18

Diagnosis and Treatment of Hair Loss

Laboratory Testing Approach

The American Journal of Clinical Dermatology recommends checking vitamin D levels, as deficiency shows a strong association with hair loss, with 70% of alopecia areata patients deficient versus 25% of controls, and lower levels correlate inversely with disease severity 21, 22
The American Journal of Clinical Dermatology suggests that serum zinc levels tend to be lower in alopecia areata patients, particularly those with resistant disease >6 months duration 21, 22

Treatment Recommendations

The British Journal of Dermatology recommends intralesional corticosteroid injections as first-line treatment for limited patchy alopecia areata, with the strongest evidence (Strength of recommendation B, Quality of evidence III) 23
The British Journal of Dermatology suggests that contact immunotherapy is the best-documented treatment for extensive patchy alopecia areata, though response rates are even lower in severe cases 23

Micronutrient Supplementation

The American Journal of Clinical Dermatology recommends 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 21, 22
The American Journal of Clinical Dermatology suggests that zinc supplementation may contribute to hair health when deficient, particularly in patients with alopecia areata and telogen effluvium 21, 22

Common Pitfalls to Avoid

The British Journal of Dermatology advises against ordering excessive laboratory tests when the diagnosis is clinically evident, as alopecia areata is typically diagnosed clinically 23
The British Journal of Dermatology recommends considering the psychological impact of alopecia areata, as it may cause considerable psychological and social disability warranting assessment for anxiety and depression 23
The British Journal of Dermatology notes that many cases of alopecia areata are self-limited, with 34-50% of patients recovering within one year without treatment, making the tendency to spontaneous remission an important consideration in management 23

Diagnostic Approach and Treatment for Hair Thinning and Nail Abnormalities

Initial Diagnostic Approach

The British Journal of Dermatology suggests that hair pattern, such as diffuse thinning at the crown with frontal hairline preservation, can indicate androgenetic alopecia, while patchy loss suggests alopecia areata 24
Exclamation mark hairs, which are short broken hairs around expanding patches, are pathognomonic for alopecia areata, as reported by the British Journal of Dermatology 24, 25
Nail changes, including pitting, ridging, or dystrophy, occur in approximately 10% of alopecia areata patients, according to the British Journal of Dermatology 24, 25

Treatment Algorithm

The British Journal of Dermatology recommends supplementing vitamin D deficiency (<20 ng/mL) according to general international recommendations for adults, with maintenance therapy due to chronicity 26
For limited patchy disease, intralesional corticosteroid injections are the first-line treatment with the strongest evidence (Strength B, Quality III), as reported by the British Journal of Dermatology 27
For extensive patchy disease, contact immunotherapy is the best-documented treatment, though response rates are lower in severe cases, according to the British Journal of Dermatology 27

Diagnostic Considerations for Nail Abnormalities

Fungal culture is mandatory before treatment, as the most common cause of treatment failure in onychomycosis is incorrect diagnosis made on clinical grounds alone, as reported by the British Journal of Dermatology 28, 29
Treatment is warranted in elderly patients, as onychomycosis can lead to serious complications, including cellulitis, particularly in those with diabetes or peripheral vascular disease, according to the British Journal of Dermatology 28, 29

Additional Considerations

The British Journal of Dermatology suggests considering aggravating factors, including medications that may cause hair loss, such as chemotherapy, anticoagulants, and beta-blockers, in elderly patients 26
Natural history matters, as 34-50% of alopecia areata patients recover within one year without treatment, making observation a reasonable option for limited disease, as reported by the British Journal of Dermatology 27

Diagnostic Approach to Diffuse Alopecia Areata

Key Diagnostic Features

The British Journal of Dermatology recommends dermoscopy as the single most useful non-invasive tool to differentiate diffuse alopecia areata, telogen effluvium, and androgenetic alopecia, with features such as yellow dots, exclamation mark hairs, and cadaverized hairs being indicative of active disease 30
Diffuse alopecia areata shows regular round yellow dots, exclamation mark hairs, cadaverized hairs, and black dots, with a positive pull test at margins of expanding areas signaling active disease 30, 31
The presence of yellow dots and exclamation mark hairs is pathognomonic for alopecia areata, and their absence is characteristic of telogen effluvium and androgenetic alopecia 30

Clinical History Patterns

Diffuse alopecia areata has an unpredictable course with potential for spontaneous remission, and may have personal or family history of autoimmune disease, with nail changes present in approximately 10% of patients 30, 31
The British Journal of Dermatology notes that diffuse alopecia areata can be diagnostically challenging and may require histopathologic confirmation, especially when presenting atypically without characteristic dermoscopic findings 30, 31

Laboratory Testing Algorithm

The British Journal of Dermatology suggests that laboratory tests, such as fungal culture, serum ferritin, TSH, and vitamin D level, help exclude mimicking conditions but do not definitively diagnose diffuse alopecia areata 30, 31
Additional tests, such as serology for lupus erythematosus and syphilis, may be indicated if systemic lupus or secondary syphilis is suspected 30, 31

Practical Clinical Algorithm

The British Journal of Dermatology recommends performing dermoscopy first, looking specifically for yellow dots and exclamation mark hairs, and if characteristic dermoscopic features are present, diagnosing diffuse alopecia areata clinically without biopsy 30
If dermoscopy is inconclusive, targeted laboratory tests should be obtained to exclude telogen effluvium triggers and tinea capitis, and if diagnosis remains uncertain, scalp biopsy should be performed for definitive histopathologic diagnosis 30, 31

Diagnostic and Management Guidelines for Diffuse Alopecia Areata (Cited Evidence)

Dermoscopic Diagnostic Features

Yellow dots observed on dermoscopy indicate active diffuse alopecia areata. 32
Exclamation‑mark hairs seen on dermoscopy are pathognomonic for alopecia areata. 32

Nail Findings Supporting Diagnosis

Nail pitting, ridging, or dystrophy is present in roughly 10 % of patients with alopecia areata and reinforces the diagnosis. 32

Ancillary Testing Recommendations

Perform a scalp fungal culture when inflammation or scaling is noted to exclude tinea capitis. 32
Order lupus serology if systemic features such as joint pain, photosensitivity, or facial rash are present. 32
Conduct syphilis serology in individuals with relevant risk factors. 32
Obtain a scalp biopsy when dermoscopic findings are inconclusive or the diagnosis remains uncertain. 32

Prognostic Indicators

Presence of nail involvement predicts a poorer prognosis in alopecia areata. 32

Natural History and Management Implications

Between 34 % and 50 % of alopecia areata patients achieve spontaneous hair regrowth within one year without any treatment. 32
Excessive laboratory testing should be avoided when characteristic dermoscopic findings already confirm the diagnosis. 32

Alopecia Areata in Children

Epidemiology and Natural History

Diagnostic Criteria

Recommended Laboratory Evaluation

Management Considerations

Psychosocial Considerations

Hair Pull Test for Diagnosis of Postpartum Telogen Effluvium

Diagnostic Technique

The hair pull test is a simple, non‑invasive bedside procedure that involves gently tugging on a cluster of approximately 40–60 hairs to evaluate hair fragility and shedding 34.
In cases of telogen effluvium, a positive hair pull test is defined by the extraction of more than six hairs, which confirms excessive telogen shedding 34.
Performing the hair pull test aids in distinguishing telogen effluvium from other causes of diffuse hair loss, such as inflammatory or scarring alopecias 34.

Evidence‑Based Facts on Telogen Effluvium

Medication‑Induced Causes

Chemotherapy agents can precipitate anagen effluvium, a distinct form of hair loss that affects actively growing hairs rather than the telogen phase 35.

Functional Subtypes of Telogen Effluvium

Short anagen syndrome is characterized by a constitutionally shortened growth (anagen) phase, leading to earlier entry into telogen and diffuse shedding 35.

Diagnostic Features

On examination, the scalp in telogen effluvium typically appears normal without inflammation or scaling, which helps differentiate it from inflammatory conditions such as tinea capitis or scarring alopecia 35.

Differential Diagnosis – Pitfalls to Avoid

Telogen effluvium should not be mistaken for alopecia areata; it presents with diffuse shedding and lacks the patchy loss and exclamation‑mark hairs that are hallmark features of alopecia areata 35.