How stable should TSH, free t4, free t3 be in a euthyroid person not on thyroid medication? I have my thyroid labs performed after fasting at 8 am in the same part of my cycle each month and my thyroid numbers can fluctuate a lot. For example in February my free t3 was 2.2 (2.3-4.4) and this month it is 3.9 (2.3-4.4), is that level of fluctuation unusual when tested under the exact same conditions? I m wondering because a couple months after a low free t3 reading my hair starts shedding like crazy, it has happened after every low free t3 reading I’ve had in the couple of years and was just wondering if it is more than a coincidence. Thanks
For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also EXTREMELY important to test vitamin D, folate, ferritin and B12
Low vitamin levels are extremely common, especially if you have autoimmune thyroid disease (Hashimoto's) diagnosed by raised Thyroid antibodies
Ask GP to test thyroid antibodies and vitamins
Private tests are available as NHS currently rarely tests Ft3 or thyroid antibodies or all relevant vitamins
If TPO or TG thyroid antibodies are high this is usually due to Hashimoto’s (commonly known in UK as autoimmune thyroid disease).
About 90% of all primary hypothyroidism in Uk is due to Hashimoto’s. Low vitamin levels are particularly common with Hashimoto’s. Gluten intolerance is often a hidden issue to.
TSH can fluctuate from day to day and hour to hour. You are right to test at the same stage as cycle, see Figure 1 ncbi.nlm.nih.gov/pmc/articl... .
However, your February 2021 test shows central hypothyroidism with low fT3, fT4 and non-elevated TSH. This needs to be checked by an endocrinologist. Also, TSH often has reduced bioactivity in central hypothyroidism so the TSH figure is not that reliable.
(Central hypothyrodism is when the pituitary is not secreting as much TSH as it should).
On the Thyroid Patients Canada site and blog Tania Sona Smith has discussed seasonality of thyroid hormones - I wonder if this is some of what you experience. thyroidpatients.ca/home/It can be difficult in our environments of artificial lighting and heating and year round availability of seasonal foods to remember that our hormone rhythms and other body functions are influenced by nature - the lengthening and shortening of days, the amount of sunlight we’re exposed to. There’s a lot more to the summer and winter solstices than an opportunity to dance naked in the woods - they mark the timing of significant change in the biological function of many animals (including humans).
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
TSH dropping but T4 / T3 not changing.
No energy after increasing medicine 
Can I discontinue Levothyroxine 50mg ? I started getting thyroid problems after taking antidepressants and mood stabilizers. Not taking now.
Thyroid help
Thoughts on my labs?
