Blood tests for hair loss: which may be needed

A clinician may consider a blood count, iron stores, thyroid testing, or selected vitamin and hormone tests when your history suggests them. These checks can identify contributors to diffuse shedding, tiredness, menstrual changes, weight change, or other symptoms. Hair loss can also follow stress, illness, rapid weight change, medicines, or scalp inflammation, which blood tests may not detect. Examination of the scalp and the timing of shedding are often just as informative.

Book an assessment if shedding is persistent, sudden, or worrying. Bring a list of medicines and supplements, describe when it began, and mention recent fever, surgery, dietary restriction, pregnancy, or major stress. Do not begin iron or high-dose supplements solely because hair is thinning; treatment should match a confirmed deficiency or another finding. Follow any fasting or appointment instructions for the specific tests ordered.

Arrange prompt medical review for rapidly expanding bald patches, scalp pain, redness, scaling, pus, or hair loss with severe fatigue, fainting, unexplained weight change, or new facial hair and irregular periods. A sudden loss of eyebrows or eyelashes also deserves assessment. Seek urgent help for symptoms of a serious allergic reaction or severe illness rather than waiting for a hair clinic appointment.

Ask whether your pattern suggests shedding, breakage, or a scalp disorder; which tests are relevant; and how results would change treatment. Ask when to expect regrowth if a trigger is found and whether a dermatology referral is appropriate.