Hello,
First of all, to evaluate the function of the thyroid gland and to adjust the medication accordingly, we rely mainly on the thyroid stimulating hormone (TSH) level. In adults the target values are between 0.3 and 5.0 mU/L, but these values may differ somewhat from one laboratory to another
A TSH of 3.6-3.8 is therefore relatively normal (perhaps a little high, which is why your doctor calls it a "lazy thyroid"). This value does not justify initiating thyroid hormone therapy such as Synthroid. However, it will be important to monitor this value (blood test) at least once a year or if you report significant symptoms of hypothyroidism, to ensure that it does not increase and become abnormal
Since thyroid hormones are responsible for regulating your metabolism, a deficiency can cause typical "slow metabolism" symptoms such as fatigue, constipation, weight gain, muscle weakness, dry skin, dry/broken hair, cold intolerance and others..
I encourage you to continue to exercise and take your medication regularly to aim for a healthy weight. Remember that the goal is 30 minutes of moderate intensity exercise (shortness of breath making normal conversation difficult) 5 times a week. Adopting a healthy diet inspired by the Mediterranean diet (see the website:
https://www.icm-mhi.org/fr/prevention/adopter-saines-habitudes-vie/alimentation-mediteraneenne) is also part of the necessary steps to reach a healthy weight. The thyroid gland is not the only "culprit" for excess weight!
I invite you to contact me again if you have any other questions about this.
Have a nice day!
Anne-Émilie Dionne, pharmacist