question: A 47-year-old woman  with generalized  tiredness and weight gain especially around waist. Patient is also intolerant to the room temperature. The next investigation to be done?
opa: Radioiodine scan
opb: Thyroid stimulating hormone (TSH)
opc: Total tetraiodothyronine level (T4)
opd: Tri-iodothyronine level (T3)