Hello,
Welcome to Health Care Magic. I read carefully your query and I understand your concern.
You have genetic predisposition for having
hypercholesterolemia and metabolic disorders (like
diabetes), the under function of the thyroid gland that you are diagnosed at 16th is also a permanent risk for elevate cholesterol, but there is a solution for preventing the high value.
First of all you should take
hormonal replacement therapy for your hypothyroid problem and monitor that cure with hormonal
blood test (TSH) by your endocrinologist; these have a benefit effect for your cholesterol blood level.
The other important component is your lifestyle, you should chose an appropriate diet with a lot of vegetable(from vegetable avoid cabbages because they induce the under function of thyroid),fruits chose white meat, fish and you should have physical activity, minimally 30 minutes of walking every day or more.
You should not gain weight especially
abdominal obesity that is a risk factor for metabolic disorder; you should monitor the weight and maintain the adequate weight for your height.
Hope I give answer to your problem. Feel free to ask me again
Take care,
Dr .Marsida JANKO