Hair loss can be associated with genetics, illness, stress, hormonal change, nutritional deficiency, thyroid problems, medications and scalp conditions. A GP assessment helps decide whether blood tests are useful and whether specialist review is needed.
Hair shedding after illness, childbirth, significant stress or weight change may be temporary, while gradual pattern hair loss often has a different cause. The history, pattern and scalp examination are as important as any blood test.
Testing should be targeted. It cannot diagnose every hair condition, but it may identify treatable contributors in the right clinical context.
Written & reviewed by
Dr George XynopoulosConsultant Physician & Cardiologist · GMC 3502763 · Reviewed by Dr George Xynopoulos, GMC 3502763
Clinical review date: 21 August 2026
View full profilePatterns that help guide assessment
Your clinician will ask when the loss started, whether shedding is diffuse or patchy, whether there are scalp symptoms and whether you have changes in energy, periods, weight, skin or nails.
| Pattern | Possible direction | Potential assessment |
|---|---|---|
| Diffuse shedding after stress or illness | Telogen effluvium or systemic trigger | History, examination and selective tests |
| Gradual widening parting or patterned thinning | Androgen-related pattern hair loss | Clinical diagnosis; consider hormonal context |
| Patchy loss or inflamed scalp | Alopecia areata, fungal or inflammatory condition | Prompt GP / dermatology pathway |
| Hair loss with tiredness or heavy periods | Iron deficiency or other systemic contributor | Targeted blood tests and GP review |
Blood tests your GP may consider
Depending on your symptoms and history, tests may include full blood count, ferritin or iron studies, thyroid function, vitamin B12, folate, vitamin D and, in selected cases, hormonal testing. Results need clinical interpretation: a result outside a laboratory range does not automatically explain hair loss on its own.
When to seek prompt assessment
Arrange a timely medical review for sudden patchy hair loss, painful or scaly scalp changes, hair loss with significant weight change, new menstrual changes or other systemic symptoms. Call 999 or attend A&E for a life-threatening emergency, including severe breathing difficulty, collapse or new stroke-like symptoms; these need urgent assessment rather than a routine hair-loss appointment.
Do not begin high-dose supplements solely for hair loss without understanding whether there is a deficiency or another cause.
Frequently Asked Questions
References
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