Hormone deficiency in middle age women is not unusual, and so women might dismiss signs like weight gain or mood swings or personality changes as part of the natural occurrence of menopause. However, deficiency of the T4 hormone is a major issue because of the parts of the body that it does regulate. Your heart rate, digestion and your body temperature can all be dismissed as just part of aging, just like mood swings, aggression and memory loss can be played off as signs of aging.
It is a serious condition. If you suspect that you might be suffering from hypothyroidism, you should contact your doctor and go in for an examination. A normal blood test will not always show a low level of the hormone T4, so you may have to specifically ask your doctor to run a blood panel to include all thyroid hormone levels. T3, T4 & T6 can all be tested for and low levels of the hormones can cause weight gain or other problems.
If the test comes back and proves or shows that you have hypothyroidism, there is no reason to be over alarmed. This condition is treatable and can be managed with hormone therapy and maybe even diet. Your doctor is there to help you with any medical condition and you should never be afraid to ask questions. Take advantage of the situation and get as much information as possible once it is detected. Of course there is a lot of information that you can obtain from the internet.