What Are Topical Thyroid Hormones?

• Thyroid hormones are produced by the thyroid, and the two most common hormones are triiodothyronine (T3) and thyroxine (T4). Synthetic thyroid analogues or thyroid sources include desiccated porcine thyroid, liothyronine, levothroxine and liotrix.
  
  Topical thyroid hormone applications refer to preparations in which thyroid hormones can be applied directly to the skin, massaged in for absorption or left to sit for a specified length of time. Preparations can include combining the hormones into a cream, shampoo, conditioner or oil as a spreadable base.
  
  

Uses for Topical Thyroid Treatment

• Topical thyroid hormones are usually used in treatment of hypothyroidism, where the thyroid does not produce a sufficient amount of such hormones. Female bodybuilding enthusiasts are keen on the effects of T4 hormone. When combined with oil for topical application, it aids in reducing adipose cell content and is supposed to tighten the skin on which it is applied while increasing elasticity. This last attribute might be due to its ability to promote collagen growth. Caution is advisable as continual, high doses of the hormone can interfere with thyroid hormone production.
  
  

Causes of Hair Loss

• The most common reason for hair loss in men is genetics. Men who inherit male-pattern baldness tend to lose hair early in life and bald extensively. It can also occur in women, where hair thins across the whole scalp.
  
  Hormonal problems like hypothyroidism can cause hair loss, as can hormonal changes in pregnancy. It can also be due to fungal infections or underlying diseases like diabetes. Medications such as anticoagulants, medication for gout, hypertension or heart disease, excess vitamin A, antidepressants and birth control pills can also cause hair loss.
  
  

Effect of Topical Thyroid on Hair Growth

• Researchers have determined that topical thyroid applications can promote the growth of follicular skin cells in wound healing. In particular, topical application of T3 in mice encourages outer route sheath cells to "transform" into epidermal and dermal sheath cells and act as key wound healing fibroblasts.
  
  Research on the role of triiodothyronine in reversing hair loss is encouraging. Topical application stimulated hair growth in mice engineered to express a gene for hairlessness. However, human tests are lacking, with only one study reporting that topical application succeeded in promoting hair growth.
  
  

Research on Topical Thyroids for Hair Loss Treatment

• In a 2008 study, van Beek and colleagues cultivated human hair follicles and treated them topically with thyroids. They observed that T4 hormones increased propagation of hair matrix keratinocytes and extended the duration of hair growth (anagen). Both hormones inhibited keratinocyte cell death and stimulated synthesis of melanin, leading to a darker skin appearance that gave the impression of more abundant hair growth.
  
  Even with such encouraging results, thyroid receptor agonists can cause cardiotoxicity. As such, studies are ongoing to identify or synthesize analogs with a short half-life and rapid clearance.