Most unlikely due to taking Vitamins. Hypothyroidism is basically deficiency of
Thyroid hormone in body. Causes may be Iodine deficiency, Viral disease, Thyroid Surgery or idiopathic. More seen in Hill areas n females. Genetic theory not proved. You can repeat the test (
TSH) from a different lab n if still its high like present test, should start Eltroxin-25 microgram daily just after rising in morn. Repeat the test after 3 months n consult.