Fatigue, Feeling Tired All the Time

CLINICAL DIAGNOSTIC MANUAL

Persistent fatigue, or feeling tired all the time, is a common complaint that can significantly affect a person’s quality of life and functional capacity. This non-specific symptom can be caused by a wide range of medical, psychological, and lifestyle factors.

A thorough assessment is essential to identify the underlying cause and provide appropriate treatment. Chronic fatigue may present as physical or mental exhaustion and could be a sign of an underlying condition requiring medical attention.

Condition	Clinical Symptoms and Signs	Suspected Diagnosis	Confirmatory Diagnosis
Depression	Persistent fatigue, anhedonia, sleep disturbances, appetite changes, feelings of worthlessness or guilt	History of depressive symptoms, psychological evaluation	Clinical evaluation, DSM-5 criteria
Microcytic anaemia	Fatigue, pallor, shortness of breath, dizziness, palpitations	Complete blood count showing low haemoglobin and microcytosis	Iron, ferritin, and total iron-binding capacity levels
Primary hypothyroidism	Fatigue, weight gain, cold intolerance, dry skin, constipation	History of hypothyroid symptoms	Elevated TSH and low free T4 levels
Sleep apnoea	Snoring, observed apnoea episodes, daytime sleepiness, morning headaches	History of sleep disturbances and associated symptoms	Polysomnography showing apnoea episodes
Medication side effect	Persistent fatigue temporally related to starting a new medication	Onset of fatigue after initiating a new medication	Medication review, evaluation of side effects
Fatigue secondary to viral infection	Fatigue, fever, muscle aches, sore throat, lymphadenopathy	Recent history of viral infection, systemic symptoms	Serological tests for viral infections, PCR for specific viruses
Diabetes mellitus	Fatigue, increased urination, increased thirst, weight loss, blurred vision	History of hyperglycaemia symptoms, family history of diabetes	Elevated fasting glucose levels, HbA1c
Chronic fatigue syndrome	Severe fatigue not improved by rest, muscle pain, concentration problems, joint pain	History of persistent fatigue for over 6 months with no clear medical cause	Clinical evaluation, exclusion of other fatigue causes
Sleep deprivation	Daytime fatigue, difficulty concentrating, irritability, drowsiness	History of inadequate or poor-quality sleep	Sleep diary, evaluation of sleep habits
Parasomnias	Abnormal behaviours during sleep, partial awakenings, nocturnal confusion	History of unusual sleep behaviours	Polysomnography and video recording during sleep