What happens is very often you go to your family doctor with complaints like being extremely tired, you get breathless easily, suffer from heavy periods, or maybe you get palpitations, exhibit anxiety neuroses, fell abnormally cold, suddenly start losing hair et al.
Sometimes these are signs of a deeper malaise, a thyroid going haywire. A pictorial description of thyroid situations and associated symptoms can be viewed here
Treating the symptoms is not enough. Sometimes treating the symptoms (only), causes more problems, that further mask the actual cause. And something that could have been , "nipped in the bud" , so to speak, is actually allowed to inadvertantly develop into a full blown serious problem.
This is an effort at depicting some cases. Actual people . If you see a case where you are prompted to say "Oh ! That really could have been me...". then its time for you to go see a endocrinologist, (which is a fancy name for a hormone doctor, who dedicates his career to balancing your hormone orchestra, and hopefully get it to make sweet music :-))