Before considering any hair loss treatment — medical or surgical — it is essential to rule out reversible causes. Iron deficiency and thyroid dysfunction are two of the most common and most treatable causes of hair loss. Treating them can restore significant hair density without any surgical intervention.
Iron Deficiency and Hair Loss
Iron is essential for DNA synthesis and cell division — including in the rapidly dividing cells of hair follicles. When iron stores are depleted, the body prioritises essential functions over hair growth, and follicles are pushed into the resting (telogen) phase prematurely.
Ferritin (stored iron) is the key marker. Standard serum iron or haemoglobin can appear normal while ferritin is depleted. A ferritin level below 30–40 ng/mL is associated with hair loss in many studies; some specialists recommend levels above 70 ng/mL for optimal hair growth support.
Who is at risk: Women with heavy menstrual periods, vegans and vegetarians, anyone with gastrointestinal conditions that impair iron absorption (coeliac, IBD), frequent blood donors.
What to test: Serum ferritin, full blood count, serum iron, TIBC.
Treatment: Iron supplementation (oral iron or, in severe cases, IV infusion). Hair regrowth typically begins 3–6 months after ferritin levels normalise. Patience is required.
Thyroid Disorders and Hair Loss
Both hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) can cause hair loss.
Hypothyroidism: The most common thyroid-related cause of hair loss. Reduced thyroid hormone slows cell turnover, affecting the hair growth cycle. Hair becomes dry, coarse, and thin — and diffuse loss occurs. The outer third of the eyebrows may also thin (a classic sign).
Hyperthyroidism: Can also cause diffuse hair loss, though less commonly than hypothyroidism.
What to test: TSH (thyroid-stimulating hormone) — the standard screening test. If abnormal, free T4 and T3 levels provide further information. Thyroid antibodies (anti-TPO) screen for autoimmune thyroid disease (Hashimoto's, Graves').
Treatment: Thyroid hormone replacement (levothyroxine for hypothyroidism) typically results in hair regrowth over 6–12 months once levels are stable.
The Importance of Testing Before Hair Transplant
Hair transplantation should not be performed until reversible causes of hair loss have been identified and treated. Operating on a patient with active iron deficiency or thyroid dysfunction risks poor graft survival and continued post-operative hair loss from native follicles.
Our pre-operative assessment always includes review of relevant blood tests.
If you suspect a medical cause for your hair loss, discuss this at consultation. Our team will review blood work as part of your assessment.