Written by Dr Amalia Annaradnam
May 2013

London Hormone Clinic

Ask the doctor — What causes fatigue?

I’ve asked my colleague Dr Amalia Annaradnam about some of the illnesses that might cause fatigue.

“There are a number of factors which may contribute to people feeling fatigued and it is a very common presentation to GPs. A lot of the time there is no clear medical reason for fatigue and it is commonly a result of the stress caused by modern day life.

However, some common medical causes of continued fatigue can be thyroid dysfunction (underactive thyroid), iron deficiency anaemia, diabetes, chronic fatigue syndrome and sleep apnoea. Other more complex medical issues such as heart failure or malignancy can also cause fatigue. More commonly in teenagers, glandular fever (a self limiting viral infection) can lead to prolonged fatigue and it is often picked up after the acute symptoms of sore throat and swollen glands have resolved.

Another common cause of tiredness is depression, which is often overlooked if the right questions are not asked. Depression can cause low mood and poor sleep which both contribute to the feeling of fatigue.