When a patient presents with fatigue, certain red flag symptoms should prompt further investigation:
- Unexplained fatigue in patients aged 40 and over with a history of smoking or asbestos exposure should lead to an urgent chest X-ray, to be completed within 2 weeks, to investigate for lung or mesothelioma NICE NG12.
- Unexplained fatigue combined with other symptoms such as cough, shortness of breath, chest pain, unexplained weight loss, or unexplained appetite loss in patients aged 40 and over also warrants an urgent chest X-ray within 2 weeks for potential lung or mesothelioma NICE NG12.
- Persistent fatigue in adults should prompt consideration of a very urgent full blood count, to be done within 48 hours, to investigate for leukaemia NICE NG12.
- Unexplained fatigue in women should lead to primary care tests, including measuring serum CA125, to investigate for ovarian cancer NICE NG12.
Additionally, for persistent fatigue, it is important to exclude alternative or contributing causes such as pain, anaemia, reduced nutritional intake, activity levels, sleep disturbance, stress, anxiety, or depression, and to manage these appropriately NICE CKS. Consideration should be given to checking serum full blood count, ferritin, vitamin B12, and folate levels, as patients can develop various types of anaemia NICE CKS. Referral to an appropriate secondary care specialist should be arranged if there is a suspected or confirmed underlying cause that cannot be managed in primary care NICE CKS. Specialist referral may also be considered for persistent, unexplained fatigue that does not meet the diagnostic criteria for chronic fatigue syndrome (CFS) if there is significant uncertainty regarding the presence of an underlying physical cause, or if a second opinion or thorough specialist evaluation would be beneficial NICE CKS.