How do thyroid hormones affect the hair follicle?

Thyroid hormones (thyroxine (T4) and triiodothyronine (T3) stimulate the production of specific enzymes to be made; this includes a key enzyme in energy production called cytochrome oxidase that is needed for cellular energy production in the electron transport chain of the mitochondria. The mitochondria are directly related to the availability of energy (ATP) in every cell to produce energy for cell growth and normal metabolic rates. This is why when thyroid hormone production is reduced, the clinical features are fatigue, cold intolerance, weight gain and constipation to name a few as the bodies metabolic processes slow down. 

T4 is produced in much larger quantities by the thyroid gland and is converted into T3 in tissues in the body, which is up to 4 times more potent than T4. 

Image from www.thyrogen.com

In the hair follicle, a reduction of thyroid hormones results in excess shedding of hair and a dry, brittle texture, but conversely an excess of thyroid hormones can also produce excess hair shedding, a reduction in hair shaft diameter, brittleness but also with greasiness from the sebaceous gland over-stimulation. 

Hair follicles express thyrotropin-releasing hormone (TRH) and thyrotropin (TSH), and have receptors to thyroid hormones T3 and T4. Here are some of the cellular mechanisms that these hormones impact on the hair follicle: 

  • T4 stimulates keratinocyte proliferation in the hair matrix
  • T3 and T4 inhibit apoptosis of the keratinocytes in the hair matrix
  • T3 and T4 prolong the duration of anagen
  • TGF-B2 is inhibited by thyroid hormones (TGF-B2 inhibits anagen, interestingly this is upregulated in androgenic alopecia and in retinoid-induced hair loss)
  • T3 and T4 stimulate hair follicle pigmentation
  • T3 and T4 reduces reactive oxygen species formation and increased amount of ROS scavengers. 
  • T3 and TSH increase follicular heat production

References: 

  1. Beek N et al, (2008), Thyroid Hormones Directly Alter Human Hair Follicle Functions: Anagen Prolongation and Stimulation of Both Hair Matrix Keratinocyte Proliferation and Hair Pigmentation, The Journal of Clinical Endocrinology & Metabolism, Volume 93, Issue 11, 1 Pages 4381–4388,available from  https://academic.oup.com/jcem/article/93/11/4381/2627273
  2. Marshall. W et al. (2017) ‘Clinical Chemistry; Chapter 11 The Thyroid Gland’, Elsevier UK
  3. Vidali. S et al (2013) ‘Hypothalamic–Pituitary–Thyroid Axis Hormones Stimulate Mitochondrial Function and Biogenesis in Human Hair Follicles’ Journal of Investigative Dermatology, Volume 134, Issue 1, 33 – 42. Available from: https://www.jidonline.org/article/S0022-202X(15)36455-1/fulltext

Covid-19 update

I have made the difficult decision to cease face to face working in the clinic. Well… it wasn’t so difficult – lets face it… public health must come first and I want to do my bit. At the moment, we are preparing for the worst. hoping that it won’t really come to what they are saying it will, or the death toll won’t rise as high as it has done in other countries, and that our amazing NHS will be able to cope…

Nobody knows at the moment. Its easy to forget what’s going on outside, sitting at home at the moment with the blue skies and sunshine all around… just my sons hacking cough to remind me why we’re all here!!

Hair loss is scary and your concerns are real and deserve to be discussed, often talking them through with someone who can give you the facts can help to alleviate some of those worries. An itchy scalp is irritating and seemingly endless. there are simple things you can do to help relieve some of this until we can get to the bottom of the cause once all this goes away (fingers crossed!)

I will be posting blog updates with hints and tips of the coming months, as well as some interesting nuggets of info that I come across from my biomedical degree as I find them.

Remember, social distancing doesn’t have to mean a black hole of isolation. I am here for an email or a chat between homeschooling my two kiddies!

Stay safe out there and see you on the other side!!

Trichology Professional Development Programme

I am proud to be part of the Trichology Professional Development Programme. We are group of well qualified and enthusiastic individuals who are instigating improvements within the Trichology Sector. We want there to be robust regulation, accredited qualification and adherence to occupational standards by all Trichologists to not only improve the professional standing of Trichology, but also public safety. We will have more to say at our official launch in May 2020! If you are a professional or wanting to get into Trichology, please see www.tpdp.co.uk to register your interest for updates.

BAHRS conference Feb 2020

Looking forward to speaking for the third time at the BAHRS conference at Aesthetic Medicine at the weekend. This year I’ve been asked to talk about the future of Trichology to the audience of hair transplant surgeons and aestheticians. I’ll let you into a secret… there are some exciting times ahead!

So welcome to my updated website!! Memories from the last few years…

What great times… more to come!!