Hair Loss Investigation in London: Blood Tests, Diagnosis, and Treatment Options
Hair loss is distressing, and its cause is often not what people expect. While genetics play a role (androgenetic alopecia is the most common cause overall), many cases of hair loss are driven by treatable medical conditions: iron deficiency, thyroid dysfunction, vitamin D deficiency, hormonal imbalance, and stress-related shedding. A targeted blood test can identify these causes in a single appointment. The Online GP by The Wellness offers comprehensive hair loss investigation at our Marylebone clinic, combining doctor-led blood testing with scalp assessment, diagnosis, treatment, and access to PRP hair restoration therapy at The London PRP Clinic by The Wellness. Same-day blood test appointments available, results in 24 to 48 hours, interpreted by a GMC-registered doctor who creates a personalised treatment plan.
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Why Hair Falls Out: The Most Common Causes
Understanding the cause is the essential first step, because different causes require completely different treatments.
Iron deficiency. One of the most common and most reversible causes of hair loss, particularly in women. Ferritin (your iron store) can be low enough to cause hair shedding even when your haemoglobin is technically "normal." Studies suggest ferritin levels below 30 to 40 mcg/L are associated with increased hair loss, though many laboratories set their "normal" threshold at 15 mcg/L. This means many women are told their iron is fine when it is actually contributing to their hair loss. At The Online GP by The Wellness, your doctor checks ferritin specifically and interprets it in the context of your symptoms, not just against a reference range.
Thyroid disorders. Both hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) can cause diffuse hair thinning. Thyroid disease affects approximately 1 in 20 people in the UK and is frequently undiagnosed for years. A full thyroid panel (TSH, free T3, free T4, thyroid antibodies) is essential in any hair loss investigation. If thyroid ultrasound is also needed (for example, if blood tests are abnormal or there is a palpable thyroid abnormality), this is available at our clinic from £195.
Vitamin D deficiency. Emerging evidence links low vitamin D levels to increased hair shedding. Approximately 1 in 5 UK adults are deficient, with higher rates in winter and in people with darker skin. Testing and supplementation are straightforward.
Hormonal factors. In women, excess androgens (as seen in polycystic ovary syndrome) can cause hair thinning on the scalp alongside excess hair growth on the face and body. Postpartum hair loss (telogen effluvium following pregnancy) is extremely common, affecting up to 50% of women, and usually resolves within 6 to 12 months. Menopause-related hormonal changes can accelerate hair thinning. Stopping hormonal contraception can trigger temporary shedding. In men, testosterone and its derivative DHT drive androgenetic alopecia (male pattern baldness).
Telogen effluvium. A diffuse shedding of hair that occurs 2 to 4 months after a significant stressor: illness (including COVID-19), surgery, severe emotional stress, rapid weight loss, crash dieting, or nutritional deficiency. The hair follicles enter the resting (telogen) phase prematurely and shed en masse. It is alarming but usually self-limiting, with full recovery over 6 to 12 months once the trigger is resolved.
Alopecia areata. An autoimmune condition causing patchy hair loss, where the immune system attacks hair follicles. It can affect the scalp, beard, eyebrows, or any body hair. Treatment may include topical steroids, steroid injections, or immunotherapy. Referral to dermatology is appropriate for moderate to severe cases.
Androgenetic alopecia. The most common cause of progressive hair thinning, affecting approximately 50% of men over 50 and approximately 50% of women by age 65. It is genetically driven but can be slowed or improved with treatment.
The Hair Loss Blood Panel
At The Online GP by The Wellness, your doctor selects the most appropriate tests based on your hair loss pattern, medical history, and clinical assessment.
A comprehensive hair loss panel typically includes ferritin and iron studies (the most important test for diffuse hair loss in women), full blood count (detecting anaemia), thyroid function (TSH, free T3, free T4, thyroid antibodies), vitamin D, vitamin B12 and folate, hormone panel (testosterone, DHEA-S, SHBG, LH, FSH in women; testosterone, SHBG in men), HbA1c (diabetes can affect hair health), inflammatory markers (CRP, ESR, for suspected autoimmune causes), and zinc (deficiency contributes to hair loss).
Results are available within 24 to 48 hours. Your doctor reviews every result, explains the findings, and creates a targeted treatment plan.
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Treatment: From Deficiency Correction to PRP
Correcting deficiencies. If blood tests reveal iron deficiency, thyroid dysfunction, or vitamin D deficiency, treating the underlying cause often reverses the hair loss. Iron supplementation (prescribed at the correct dose and formulation, with rechecks at 8 to 12 weeks), thyroid medication (levothyroxine for hypothyroidism), and vitamin D supplementation are all straightforward interventions that frequently produce dramatic improvement.
Topical treatments. Minoxidil (available over the counter as a scalp solution or foam) is the most widely used topical treatment for androgenetic alopecia in both men and women. It works by increasing blood flow to the hair follicles and extending the growth phase of the hair cycle. Results take 4 to 6 months and require ongoing use.
Prescription medication. Finasteride (1mg daily, for men) blocks the conversion of testosterone to DHT, the hormone primarily responsible for male pattern hair loss. It is effective in approximately two-thirds of men but requires discussion of potential side effects (a small percentage report reduced libido or erectile changes, which usually resolve on stopping the medication). Your doctor will discuss the evidence and your individual risk-benefit profile. Spironolactone (for women) can be considered for androgen-driven hair loss, prescribed off-label after appropriate assessment.
PRP (platelet-rich plasma) therapy. Available at The London PRP Clinic by The Wellness, our sister clinic in the same Marylebone location. PRP uses concentrated growth factors from your own blood, injected into the scalp to stimulate follicular activity. The largest meta-analysis to date (Anitua et al., 2025, Dermatology and Therapy, 43 RCTs, 1,877 participants) confirmed that PRP significantly increases hair density and thickness. Courses start from £1,455 for 3 sessions. PRP works best when combined with medical treatment of any underlying deficiency.
Specialist referral. For alopecia areata, scarring alopecia, or hair loss that does not respond to first-line treatment, we refer to dermatologists with a special interest in hair disorders.
The Wellness Advantage: Investigation and Treatment Under One Roof
Most clinics offer either investigation (GP or blood test service) or treatment (PRP clinic, dermatologist) but not both. The Wellness group integrates the entire pathway.
Your GP at The Online GP by The Wellness investigates the cause with blood tests and clinical assessment. If a deficiency is found, your GP treats it. If PRP is appropriate, The London PRP Clinic by The Wellness delivers it from the same Marylebone location. If dermatology referral is needed, your GP arranges it. If thyroid ultrasound is needed, it is performed at the same clinic. Everything is coordinated, and nothing falls through the gaps.
Start Your Hair Loss Investigation - WhatsApp | Email: team@thewellnesslondon.com | Call: 020 3951 3429
Frequently Asked Questions
What blood tests should I have for hair loss? Ferritin, thyroid function, vitamin D, B12, full blood count, hormones, HbA1c, zinc. Your doctor selects based on your presentation.
What is the most common cause? Androgenetic alopecia overall. Among treatable causes: iron deficiency, thyroid disorders, and vitamin D deficiency.
Can you treat hair loss? Yes. Deficiency correction, topical treatments, prescription medication, and PRP therapy. Plus dermatology referral when needed.
What is PRP? Growth factor therapy using your own blood. Injected into the scalp to stimulate hair follicles. Courses from £1,455 at The London PRP Clinic by The Wellness.
Should I see a GP or dermatologist? Start with a GP for blood tests and initial assessment. Dermatology referral if the diagnosis is unclear or treatment is not working.
How long until I see improvement? Depends on the cause. Deficiency correction: 3 to 6 months. PRP: 3 to 4 months for initial results. Minoxidil/finasteride: 4 to 6 months.
Is hair loss a sign of something serious? Usually not, but it can indicate thyroid disease, anaemia, autoimmune conditions, or hormonal disorders. Investigation is important.
The Online GP by The Wellness provides private doctor-led healthcare from our Marylebone clinic. Hair loss investigation, blood testing, treatment, and PRP therapy all available from The Wellness group. Contact us on WhatsApp at +44 7961 280835, email team@thewellnesslondon.com, or call 020 3951 3429.
References
Anitua E et al. Platelet-rich plasma for androgenetic alopecia: a systematic review and meta-analysis of 43 RCTs. Dermatology and Therapy. 2025.
British Thyroid Foundation. Thyroid disease and hair loss. Updated 2025.
NICE. Iron deficiency anaemia. CKS. Updated 2025.
British Association of Dermatologists. Hair loss guidelines. Updated 2024.
Rushton DH. Nutritional factors and hair loss. Clinical and Experimental Dermatology. 2002;27(5):396-404.