Symptoms that your thyroid is not working 100% are more common than you think. Hypothyroidism affects up to 15% of Americans. It is much more common in women than in men.
And when your thyroid isn't working very well you start to experience symptoms such as weight gain, fatigue, constipation, bloating, hair loss, cold intolerance and even depression.
Three methods to know if your thyroid is slow:
1) Are you experiencing these symptoms I mentioned? FATIGUE, COLD INTOLERANCE, HAIR LOSS OR EVEN EYEBROW HAIR LOSS, WEIGHT GAIN DESPITE APPROPRIATE DIET AND EXERCISE
2) Take your temperature at dawn
You wake up in the morning and keep a thermometer by your side. Take your temperature before getting out of bed and if your temperature is low for 5 consecutive days there is a chance that your thyroid is not working well.
A normal temperature is between 97.8-98.2℉ or 35.5-37℃
If your temperature is lower than 97.6℉ or 36.4℃, it is likely that your thyroid is having some difficulties.
If you are still menstruating - be careful to only start measuring your temperature in the morning starting on the second menstrual day as ovulation in the menstrual cycle can actually change your body temperature in the morning.
3) Order lab tests including a blood thyroid panel.
The test can measure thyroxine (T4) and triiodothyronine (T3) levels and perhaps even detect high levels of antibodies such as anti-thyroperoxidase (anti-TPO).
https://www.thyroid.org/thyroid-matter-especially/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566469/