Hair loss is a common health and cosmetic concern that can cause distress in both men and women. Although shedding around 50–100 hairs per day can be part of the normal hair growth cycle, persistent, excessive, or sudden hair loss may require medical evaluation.
Many people try supplements or expensive shampoos without first identifying the underlying cause. However, hair loss can be associated with several factors, including genetics, hormonal changes, nutritional deficiencies, certain medications, stress, and medical conditions.
A hair loss test is not a single test that can diagnose every cause of hair shedding. Instead, a doctor may recommend selected blood tests based on the person's symptoms, medical history, diet, medications, and scalp examination. These may include tests for iron deficiency, thyroid dysfunction, or vitamin deficiencies.
In this guide, we explain which blood tests may help investigate hair loss, when nutritional or hormonal factors may be involved, and how Nawat Medical Laboratory can support your laboratory testing needs.
What Are the Most Important Blood Tests for Hair Loss?
There is no universal panel that every person with hair loss must undergo. The most appropriate hair loss test depends on the suspected cause. A healthcare professional may recommend one or more of the following investigations.
1. Ferritin Test and Iron Stores
Ferritin is a protein that stores iron in the body. A ferritin blood test helps assess iron reserves, and low ferritin levels may indicate depleted iron stores, even when the haemoglobin level is still within the laboratory reference range.
Iron deficiency can contribute to hair shedding in some people. Iron is essential for several biological processes, including oxygen transport and normal cell function. When iron stores are low, a doctor may investigate whether iron deficiency is contributing to the patient's symptoms.
A complete blood count (CBC) may be ordered alongside a ferritin test to assess for anaemia. Depending on the clinical situation, additional iron studies may also be appropriate.
It is important to understand that there is no single ferritin threshold, such as 70 ng/mL, that has been universally established as necessary for healthy hair growth in everyone. Ferritin results must be interpreted in context because inflammation and other conditions can affect ferritin levels.
If your doctor suspects iron deficiency, an iron test and ferritin measurement may help clarify your iron status. Do not start iron supplements without appropriate medical advice, as unnecessary iron intake can be harmful.
2. Thyroid Test: Checking TSH Levels
The thyroid gland produces hormones that help regulate metabolism and affect several body functions, including the normal hair growth cycle. Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) may be associated with hair thinning or shedding.
A thyroid test may be recommended when hair loss occurs alongside symptoms or medical history suggesting a thyroid disorder.
- Hypothyroidism: An underactive thyroid may be associated with dry, coarse hair, hair thinning, fatigue, sensitivity to cold, or unexplained weight gain.
- Hyperthyroidism: An overactive thyroid may cause symptoms such as a rapid heartbeat, heat intolerance, tremors, or unexplained weight loss. Hair thinning may also occur.
- TSH testing: Thyroid-stimulating hormone (TSH) is commonly used as an initial test to assess thyroid function. Depending on the result and clinical context, a doctor may request free T4 or other investigations.
A thyroid test cannot identify every cause of hair loss, and an abnormal result does not automatically prove that the thyroid is the only reason for shedding. The findings should be interpreted alongside symptoms and other clinical information.
For people with suspected thyroid-related hair loss, appropriate testing can help a clinician determine whether further assessment or treatment is needed.
3. Vitamin D and Vitamin B12 Tests
Vitamins and minerals support many functions in the body, but their relationship with hair loss varies depending on the nutrient and the individual.
Vitamin D
Vitamin D is involved in several biological processes, and research has explored its association with different types of hair loss. Some studies have found lower vitamin D levels in certain groups of people with diffuse hair shedding. However, low vitamin D does not necessarily mean it is the cause of an individual's hair loss.
A vitamin D blood test measures the level of 25-hydroxyvitamin D, commonly written as 25(OH)D. A doctor may recommend this test when a deficiency is suspected based on symptoms, risk factors, or the clinical assessment.
If a deficiency is confirmed, the appropriate treatment and dosage should be determined by a healthcare professional rather than by taking high-dose supplements without testing or advice.
Vitamin B12
Vitamin B12 is essential for red blood cell formation and DNA synthesis. A deficiency can cause megaloblastic anaemia and neurological symptoms, among other health problems.
Vitamin B12 deficiency is not a universal cause of hair loss, but testing may be appropriate when the patient's history, diet, symptoms, or blood count suggests a possible deficiency.
Depending on the clinical findings, a doctor may recommend vitamin B12 testing as part of a broader hair loss test evaluation.
4. Complete Blood Count (CBC)
A complete blood count is a common blood test that measures several components of the blood, including red blood cells, haemoglobin, white blood cells, and platelets.
A CBC may help identify:
- Anaemia: Low haemoglobin or abnormalities in red blood cell measurements may suggest anaemia, which can sometimes be related to iron deficiency or other nutritional problems.
- Abnormal white blood cell counts: These findings may indicate an infection, inflammation, or another condition, but they do not independently diagnose a scalp disorder or an autoimmune cause of hair loss.
- Other blood abnormalities: The results may help a doctor decide whether further investigations are necessary.
When clinically indicated, a CBC and ferritin test can provide complementary information about blood health and iron status. However, neither test alone can establish the cause of every type of hair loss.
Is Hair Loss Always Hereditary?
No. Genetic hair loss is common, but it is only one of several possible explanations for thinning or excessive shedding.
Androgenetic alopecia, also known as pattern hair loss, is influenced by genetics and the effects of androgens on susceptible hair follicles. In some people, the hormone dihydrotestosterone (DHT) contributes to gradual follicle miniaturisation.
Other possible causes include the following.
Telogen Effluvium
Telogen effluvium is a type of temporary, diffuse hair shedding that can occur after a significant physical or emotional stressor. Possible triggers include a high fever, major surgery, childbirth, rapid weight loss, or severe stress.
Shedding often becomes noticeable around two to three months after the triggering event. Recovery depends on the cause and the individual's health.
A hair loss test may be considered if the history or symptoms suggest an underlying nutritional deficiency, thyroid disorder, or another medical condition. Blood tests are not necessary for every person with telogen effluvium, however.
Hormonal Changes
Hormonal changes may contribute to hair loss in some circumstances. In women, possible factors include the postpartum period, menopause, or conditions associated with excess androgen levels, such as polycystic ovary syndrome (PCOS).
Hormone testing is not routinely required for every woman experiencing hair loss. A clinician may consider targeted tests when there are additional signs, such as irregular menstrual cycles, new or worsening acne, or excessive facial hair.
In men, typical pattern hair loss is often diagnosed through clinical examination and may not require blood tests unless other symptoms suggest an additional condition.
Nutritional Deficiencies
Low iron stores and certain nutritional deficiencies may contribute to hair shedding in some people. A doctor may recommend an iron test, ferritin measurement, vitamin B12 test, or vitamin D test according to the patient's history and examination.
If initial tests do not reveal an explanation, the clinician may consider other causes rather than assuming that a deficiency is present.
When Should Hair Loss Be Medically Evaluated?
Some daily hair shedding is normal. However, it is advisable to seek medical assessment if you experience any of the following:
- Sudden or excessive shedding: A noticeable increase in hair loss over a short period, especially when the cause is unclear.
- Hair loss with other symptoms: Persistent fatigue, pale skin, unexplained weight changes, unusual sensitivity to cold or heat, or menstrual irregularities may warrant further evaluation.
- Scalp changes: Severe itching, redness, scaling, pain, or signs of scarring should be assessed by a healthcare professional.
- Distinct bald patches: Round or clearly defined areas of hair loss may be associated with alopecia areata or other scalp conditions.
- Progressive thinning: Hair that continues to become thinner or less dense over time may benefit from a dermatological assessment.
A clinician may examine the scalp and hair pattern before deciding whether alopecia blood tests are appropriate. Blood tests can help investigate selected medical causes, but they cannot diagnose every type of alopecia. Some conditions require a detailed scalp examination, dermoscopy, or occasionally a scalp biopsy.
Seek prompt medical assessment if hair loss is accompanied by significant scalp inflammation, pain, or rapidly developing patches.
How to Prepare for a Hair Loss Test
Preparation depends on the specific tests ordered. Before your appointment, consider the following points.
- Ask whether fasting is required: Many tests used to investigate hair loss do not require fasting. However, additional tests included in the same blood draw may have different preparation requirements. Follow the instructions provided by your doctor or laboratory.
- Tell your healthcare professional about supplements: Biotin, which is found in some hair, skin, and nail supplements, can interfere with certain laboratory assays, including some thyroid tests and vitamin D measurements.
- Do not stop prescribed medication on your own: If you take biotin or other supplements, ask your healthcare professional or laboratory whether you need to pause them before testing and for how long. The appropriate interval depends on the dose and the specific laboratory method.
- Provide a complete medication history: Tell the clinician about prescription medicines, over-the-counter products, and supplements you use.
- Mention recent health changes: Recent illness, surgery, childbirth, significant weight loss, dietary restrictions, and changes in your menstrual cycle may help the clinician interpret your results.
There is no universal rule that everyone must stop biotin for three to seven days. Because biotin interference varies by dose and test method, follow the advice of the healthcare professional or laboratory performing the test.
At Nawat Medical Laboratory, contact the team before your appointment if you need clarification about preparation requirements for your selected tests.
Book a Hair Loss Test at Nawat Medical Laboratory
Finding the right laboratory tests can be a useful step toward understanding possible medical contributors to hair loss. Nawat Medical Laboratory offers a range of laboratory services, including a dedicated hair loss testing package listed on its website.
If you are considering a hair loss test, the appropriate tests should be selected according to your symptoms and your healthcare professional's recommendations. Depending on the clinical assessment, the investigation may include ferritin, a CBC, a thyroid test, or a vitamin D measurement.
You can explore the available package and confirm its current test components, price, appointment options, and sample collection arrangements before booking.
Explore the hair loss testing package:
Hair Loss Testing Package – Nawat Medical Laboratory
You may also explore the laboratory's thyroid function testing package and comprehensive vitamin package to review the available options.
The laboratory tests that are right for you will depend on your individual circumstances. Discuss the results with a qualified healthcare professional so that any treatment addresses the underlying cause rather than hair loss alone.
Frequently Asked Questions About Hair Loss Tests
What blood tests are needed to investigate hair loss?
Depending on the patient's symptoms and medical history, a clinician may recommend a CBC, ferritin or other iron studies, a thyroid test, vitamin B12, or vitamin D testing. Not everyone needs all of these tests, and some causes of hair loss can be diagnosed through scalp examination without blood tests.
Which hormone is responsible for hair loss?
Dihydrotestosterone (DHT) contributes to androgenetic alopecia in genetically susceptible hair follicles. Thyroid hormone abnormalities may also be associated with hair shedding. The appropriate evaluation depends on the hair loss pattern and any accompanying symptoms.
What is the best hair loss test?
There is no single best hair loss test for everyone. A clinician may recommend targeted blood tests based on the suspected cause, such as ferritin testing for possible iron deficiency or a thyroid test when thyroid dysfunction is suspected.
Which vitamin deficiency can contribute to hair loss?
Low vitamin D and certain other nutritional deficiencies have been associated with hair loss in some groups. However, the association varies, and a low vitamin level does not automatically establish the cause of hair shedding. Testing and treatment should be guided by clinical assessment.
Can vitamin B12 deficiency cause hair loss?
Vitamin B12 deficiency can cause anaemia and other health problems. Its role in an individual's hair loss depends on the overall clinical picture. A clinician may recommend a B12 test when symptoms, diet, or other findings suggest a possible deficiency.
Can blood tests diagnose alopecia?
Alopecia blood tests can help identify selected underlying conditions, such as iron deficiency or thyroid dysfunction, when these are suspected. However, blood tests cannot diagnose every type of alopecia. A scalp examination and, in some cases, additional dermatological investigations may be necessary.
Do I need to fast before a hair loss blood test?
Not usually for many individual tests used in hair loss investigations, but preparation depends on the tests ordered together. Confirm the instructions with your healthcare professional or laboratory before your appointment.
Conclusion
Hair loss can have several causes, including genetics, hormonal changes, nutritional deficiencies, stress, and medical conditions. Choosing the right hair loss test starts with understanding the pattern of hair loss and assessing the individual's symptoms and medical history.
Tests such as ferritin, a CBC, a thyroid test, and vitamin D measurement may be useful when clinically indicated. An iron test or other targeted investigations may also be appropriate in selected cases. However, no single blood test can explain every case of hair loss, and not everyone needs a comprehensive panel.
Nawat Medical Laboratory provides laboratory testing options that may support this evaluation. Explore the available hair loss package and consult a qualified healthcare professional to determine which tests are suitable for you.
Medical disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Test selection and interpretation should be guided by a qualified healthcare professional.
Medical References
- MedlinePlus – Ferritin Blood Test
- PubMed – Serum Ferritin and Vitamin D Levels in Patients With Diffuse Hair Loss
- Merck Manual Professional Edition – Alopecia
- U.S. Food and Drug Administration – Biotin Interference With Laboratory Tests