Why Thyroid Blood Tests Are Not Completely Accurate
A proper functioning thyroid can make a substantial difference to your well-being and overall health.
Traditionally, when a person suspects that they may have an underactive thyroid and are exhibiting multiple hypothyroid symptoms, a GP will order a thyroid stimulating hormone blood test (TSH levels). This test generally has a TSH level of 0.5-5 (depending which clinic runs your test). If your results come back within this range, your thyroid function is considered normal despite numerous other symptoms such as fatigue, weight gain, brain fog, sore throat, anxiety, etc..
The evidence for a narrower TSH range is compelling and previous accepted reference ranges are no longer valid. Clients with ranges of TSH as low as 2.5 are now considered possibly hypothyroid even though it sits within the ‘normal’ range.
A Naturopath considers a TSH of 2.5 or higher combined with other symptoms as warranting further tests to see if you do in fact have an underactive thyroid.
Other tests we consider are T3 and T4 levels, thyroid antibodies, reverse T3, urinary spot iodine test, basal body temperature and Thyroflex testing.
Endocrinologist, Dr R.I.S Bayliss states that traditionally a person’s thyroid was tested via the patients pulse rate, sense of well-being, their skin texture, cold tolerance, bowel function, and the speed of which the patient’s deep tendon reflexes relax.
Keep in mind there are many factors that affect thyroid function. These include: inflammation, toxicity, hormone imbalance, nutritional factors, immune dysfunction, adrenal dysfunction, and gastrointestinal dysfunction, but our comprehensive testing allows us to cross check these functions as per your symptomology.
- TSH- Thyroid stimulating hormone- This test lets you know how much thyroid stimulating hormone you have. TSH signals the thyroid to produce the hormones T3 (triiodothyronine) and T4 (thyroxine) which act by stimulating the metabolism of tissues in the body. TSH alone it is not accurate as there are other factors which effect it.
- Basal body temperature- temperature is measured via the armpit upon waking for 3 consecutive days and an average is taken (not to be taken on first day of menstruation). A normal thyroid function will give a reading of 36.4-37.1 C . A 36.4C or lower can indicate underactive thyroid.
- Thyroid antibody test: this test will indicate if there is an autoimmune reaction occurring against the thyroid gland.
T3 and T4: T3 and T4 are regulated by TSH levels. T4 (Thyroxine) is converted into T3, which is your active thyroid hormone that acts on the body’s tissues to control metabolism.
Low T4 and/or elevated TSH may indicate hypothyroidism.
Free T3: 4.0-8.0 pmol/L
Free T4: 10-25 pmol/L Subclinical hypothyroidism 2.5-4.0 mlIU/L
Reverse T3: High reverse T3 levels down regulates conversion of T4 to T3 with more RT3 being produced then T3 hence a reduction in metabolism.
- Urinary Iodine test: Checks the amount of Iodine in your body. Iodine is essential for Thyroid hormone production.
- Thyroflex test: A reflex test done via a Thyroflex machine. Reflexes are controlled by the thyroid and are the original testing method for thyroid function.
As you can see, there is a lot more to consider when looking into thyroid function and testing, but further options are available if you suffer from thyroid symptoms and your TSH levels are within normal range.
NatMed is available for all your health needs on 08 9339 1999
Bayliss (1971) Medical society’s transactions speech
Derry, D (2006) Breast Cancer and Iodine, Trafford publishing
Wartofsky , L and R Dickey (2005) The evidence for a narrower thyrotropin reference range is compelling, Journal of clinical Endocrinology Metabolism, Sep: 90 (9) 5483-8