Why am I still tired?

Your thyroid is the central gear

Think of your thyroid as the central gear in a complex engine. Every cell in your body needs thyroid hormone, and it sets the pace at which those cells produce energy. When that gear slows, everything connected to it slows too: energy, body temperature, digestion, weight, mood, memory and motivation.

That’s why low thyroid function causes such a wide range of symptoms, and why they are so often put down to stress, age or simply being busy.

TSH tells only part of the story

The standard thyroid blood test measures TSH, a signal from the pituitary gland asking the thyroid to work, and sometimes free T4. It’s an important test, but on its own it can’t show how well thyroid hormone is actually working in your body.

Your thyroid mainly releases T4, a storage hormone. To work, T4 has to be converted into T3, the active form, largely in the liver, the gut and the body’s tissues. Some is turned into reverse T3 instead, an inactive form. None of this shows up in a TSH result.

Common reasons symptoms continue

• Poor conversion. T4 isn’t being converted into enough active T3, so your cells don’t get what they need even when T4 looks fine.
• Autoimmunity. In the UK, Hashimoto’s is the most common cause of hypothyroidism. It’s identified with a thyroid antibody test, which isn’t part of a routine check.
• Contributing factors. Nutrient deficiencies, blood sugar imbalances, adrenal stress, and gut or liver problems can all hold thyroid hormone back.
• Normal isn’t always optimal. Standard reference ranges are wide. A result can be within range and still not be right for you.

What a fuller assessment looks at

We start by building your baseline with the Thyroid Profile and a functional medicine blood chemistry profile. Then we test the thyroid fully — free T3, reverse T3 and antibodies — alongside the five contributing factors.