The Doc told my family (5 sisters) that 99% of the people in the world with underactive thytoid are female. My dad had a severely underactive thyroid in later life. As a result my sisters and I were encouraged to get our checked regularly. Of the 5 sisters, 4 are already on medication, me included, and the remaining sister won't get her checked. Thyroid problems cause numerous health issues and chould be checked regularly.