Thyroid Lab Tests - this is what to ask for

In my experience, GP’s really don’t know a great deal about the thyroid so I have put together the following guide to assist you when asking for the right tests. You may need to push to get some of these labs done, especially if you rely on the cash-strapped UK NHS.

I’ve not only written a list of tests to ask for, but also why you need to get them done. This list is recommended by the UK Thyroid Charity and many experts in this field, including the New York Times best-selling author Dr Izabella Wentz who is arguably the most knowledgeable thyroid expert on the planet, and someone I’ve corresponded with about this.

If you take thyroxin medication you must ensure you don’t take them on the day of the blood test as this will affect the results.

The absolute basics to check you have adequate thyroid levels:
TSH and Free T4

To check conversion of Free T4 is adequate (and conversion can be an issue, even if your doctor thinks otherwise):
Free T3 

once you have optimal levels of TSH and Free T4 listed above you should get another Free T3 done in at least 6 weeks to ensure levels are good. I will list what good levels are later. You should also ask for:
Reverse T3
(It’s unlikely this will get done, but if you’re over-converting Free T4 you’ll end up with too little usable Free T3 and too much unusable reverse T3. This test is usually done when nothing else works. If the doctor refuses you can always go back and ask for it if all other labs fail to reveal anything.)

It is the presence of thyroid antibodies that confirm Hashimoto’s or Graves’ disease (hyperthyroidism). This test is vital. Don’t leave without getting this one:
TPO, TgAb and TSI

As we highly suspect Hashimoto’s, which is an autoimmune disease, you should be screened for all other common antibodies. This might seem excessive but autoimmune diseases don’t usually occur alone. It was this test that caught my pernicious anaemia and atrophic gastritis:
Anti-DNA, SS-A (Ro), SS-B (La), Smith (Sm), Ribonuclear Protein (RNP), SCL-70, Anti-Jo 1 Abs, Anti-Smooth Muscle Ab,s Anti-mitochondrial Abs, Liver/Kidney Microsomal Abs, Anti Gastric Parietal Cell Abs, Intrinsic Factor Abs, Anti-Ovary Abs, Anti-Adrenal Abs, Anti-Skeletal Muscle Abs, Pancreatic islet cell Abs.

If you suspect Hashimoto’s you should look for markers for autoimmune inflammation:
ANA, CRP, ESR, Homocysteine

Routine vitamins:
Vitamin B12
Vitamin D (1,25-Dihydroxy)
Vitamin D is a vital secosteroid (a hormone), used by every cell in the body. Vitamin D3 deficiency is linked with a variety of different health problems, from depression to cancer, and osteoporosis to Parkinson’s Disease. Risk of heart disease and diabetes is also increased in people with deficiency and disease progression can be more severe in people with Fibromyalgia and Multiple Sclerosis. It’s estimated that ninety per cent of people in the UK have insufficient levels.

For weight issues:
Ferritin and Iron Saturation

Sex and Adrenal Panel:
Estrogen, Progesterone, Testosterone, DHEA and Cortisol

Possible root causes of Hashimoto’s and other autoimmune symptoms:
Epstein Barr Virus

You should also request all other basic blood tests offered in a routine panel as well as:
Blood Cholesterol 
Blood Glucose
Full Blood Count
Liver Function Tests
Bone Profile (calcium)

Make sure you request a copy of the full test results from your doctor, don’t just rely on them to tell you it’s all ‘ok’.

Interpreteing your results

What is ‘in range’ according to a doctor isn’t necessarily optimal (which is where you’ll start to feel normal). When it comes to your thyroid you need to look at the following and make sure you hit the optimal level in all the following three areas:

Test Result Meaning
TSH Below 0.5 mIU/L Hyperthyroidism
0.5 – 1 mIU/L Optimal Level
1 – 2.5 mIU/L In range but subclinical hypothyroidism
Over 2.5 mIU/L Hypothyroidism
Free T4 Below 12 pmol/L Hypothyroidism
12 – 22 pmol/L Optimal Level
Over 22 pmol/L Hyperthyroidism
Free T3 Below 2.63 pmol/L Hypothyroidism
2.63 – 4 pmol/L In range
4 - 5.7 pmol/L Optimal Level
Over 5.7pmol/L Hyperthyroidism