Lab Tests for Hair Loss

While not every patient with hair loss needs a blood laboratory work up, this can be helpful in some cases. Likewise, if you are having other symptoms such as scalp itching, redness, flaking or unusual distributions of hair loss you may be suffering from seborrheic dermatitis, tinea capitis, psoriasis, or cicatricial (scarring alopecia). You should first see your dermatologist for a scalp examination.

Thyroid abnormalities are frequently linked with hair loss. It may be either hyperthyroidism (elevated thyroid hormone production, as detected by a low TSH) or hypothyroidism (decreased thyroid production, as detected by an elevated TSH.) However the incidence of thyroid abnormalities, and the incidence of hair thinning are both so common that it is difficult to know whether the connection is causative. If thyroid is the cause, the body must be in its corrected state of metabolism for a full 6-12 months before the hair will return to its normal growth pattern. Because of the risk of thyrotoxicosis, one should never take thyroid supplements without first checking with your doctor.

Ferritin (a measure of iron stores). The connection between hair loss and low iron stores is controversial. Low iron has traditionally been thought to contribute to hair loss. More recent studies have found no connection whatsoever1,2. It can be worth checking in women who have a diet low in iron or who have very heavy menses. However there is no guarantee that increasing the body’s iron stores will help stop the hair loss or regrow the hair. Because of the potential risk of iron toxicity, one should never supplement without checking with your doctor first. If it is very low, there are various over-the-counter formulations of iron that act gradually and will not cause constipation. If you are sulfa allergic be sure not to take any of the ‘ferrous sulfate’ formulations.

Vitamin D has become a hot topic in medicine for its potential role in a variety of health conditions. At present there is little evidence to demonstrate that supplementing vitamin D will help regrow hair. Nonetheless, it can be worth checking and supplementing if it is very low. Depending on blood levels, we may recommend an over-the-counter supplement or may prescribe a single 8-week course of prescription strength Vitamin D. We do NOT prescribe vitamin D unless the levels have already been checked and found to be low.

B-12. A number of doctors recommend B-12 injections to their patients with hair loss. This is based on reports of hair graying and hair loss in patients with B-12 deficiency. However, there is little data to suggest that extra B-12 injections, above and beyond normal levels, will help hair grow better.

Biotin. Many doctors also recommend biotin for their patients with hair loss. This also is related to the fact that severe biotin deficiency has been reported to cause alopecia. As with B-12, there is no evidence to support improved hair growth with biotin supplementation above and beyond the body’s normal levels.


1 Bregy A, Trueb R. No association between serum ferritin levels>10μg/l and hair loss activity in women. Dermatology. 2008;217:1-6.

2 Olsen EA, Reed KB, Cacchio PB et al. Iron deficiency in female pattern hair loss, chronic telogen effluvium, and control groups. J Amer Acad Dermatol. 2010;63:991-999.

3 Juangbhanit C, Nitidanhaprabhas P, Sirimachan S, Areekul S, Tanphaichitr VS. Vitamin B12 deficiency; report of a childhood case. J Med Assoc Thai. 1991;74:348-54.

4 Fujimoto W, Inaoki M, Fukui T, Inoue Y, Kuhara T. Biotin deficiency in an infant fed with amino acid formula. Journal of Dermatology. 2005;32:256-61.

5 Limat A, Suormala T, Hunziker T, et al. Proliferation and differentiation of cultured human follicular keratinocytes are not influenced by biotin. Arch Derm Res. 1996;288:31-8.

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