This question was asked during a consultation and it is my Question of the Month:

“I am on thyroxine for an underactive thyroid. I have been told my dose is enough because my thyroid test is normal. But I still feel tired, cannot lose weight, my skin is dry and I have dark and rough skin around my eyes. I feel like I need more thyroid replacement. Why is this happening?”

For most conventional doctors, an underactive thyroid is “a doddle” to diagnose and treat: if the TSH (Thyroid stimulating hormone) level is high with symptoms for several months, they diagnose an underactive thyroid, start Thyroxine (T4) replacement, (Levothyroxine, Eltroxin) and send the patient on their way. Unfortunately it is not so simple for the patient.

Thyroxine or T4, which is about 90% of the thyroid hormone in the body, is actually the inactive thyroid hormone.
To make you feel better from your symptoms of underactive thyroid, T4 must be processed into the active thyroid hormone T3 – triiodothyronine – which is what treats your symptoms. T3 is short lived and short acting, and forms about 10% of the thyroid hormone in your body.
When we depend on T4 alone for treatment, we are assuming that T4 will effectively convert in the body to T3.

Over time, many patients on T4 (Levothyroxine, Eltroxin) treatment, notice a return of hypothyroid symptoms – weight gain, depression, brain fog, aches and pains, fatigue, infertility, hair loss, low sex drive – and for some patients, the symptoms never fully disappear in the first place. You may be one of them.
Because your T4 levels are increased, this feeds back to the brain and the pituitary gland, which reduces the level of Thyroid Stimulating hormone (TSH).

This is because your brain now thinks the thyroid does not need any more stimulation, what with all the T4 floating around.
But if for some reason, you are not converting T4 to T3, you will still FEEL hypothyroid — as you don’t have enough T3 available to actually resolve the hypothyroid symptoms.

Not having enough selenium or zinc, which are vital to the conversion process, could be a reason for not converting T4 to T3.
Even more interesting is that taking T4 in itself, could deplete your reserves of selenium and zinc.
If you are perimenopausal, the changing levels of estrogen, progesterone, DHEA and testosterone all have an impact on how much thyroid hormone is bound to proteins in the blood and thus, how much is available to carry out vital functions.

When carrying out hormonal assessments at Reverse Time, we look at the levels of all these, TSH, T4, T3, and sometimes a special test called Reverse T3.
Balanced Thyroid hormone replacement – Based on these you may find that you feel better when you take a combination of T4 and T3, alongside supplements of zinc and selenium. These can be prescribed as synthetic or bio-identical hormone preparations.

A note about supplements – I prefer liquids, as I don’t have to worry about the capsule shells not dissolving. (This is a personal opinion!)
Some useful supplements for thyroid and general wellness are listed below.

  • Liquid Zinc – Nutrisorb® Liquid Zinc Plus Ascorbate (Biocare) 30ml: take 10 drops mixed in 150ml of water or diluted squash at night.
  • Liquid Vitamin D – Nutrisorb® Liquid BioMulsion® D (1000iu) 10ml – 1 drop daily.
  • Vitasorb® E (Liquid Vitamin E) 15ml – 1-3 drops daily
  • Vitasorb® A (Liquid Vitamin A) 15ml – 1 drop daily
  • Thyroid support (NOT to be taken if you are on thyroid medications). TH Intensive – 1 sachet mixed with water daily first thing morning, as per advise from your doctor

​The above products are Vegan and they will not affect any underlying intolerance.

If you purchase any Biocare supplements after registering as a user and logging on to Biocare (, please use the following code at checkout for a discount: P6939

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