| Cause | Details | Tests | Management | 
 | Anaemia | 
Common cause of fatigue due to low haemoglobin levels.May be due to iron deficiency, vitamin B12 deficiency, or chronic disease.Associated symptoms: pallor, shortness of breath, dizziness. | 
Complete blood count (CBC)Serum iron, ferritin, B12, and folate levelsPeripheral blood smear | 
Iron supplements for iron deficiency anaemiaVitamin B12 injections or oral supplements for deficiencyTreat underlying chronic disease if present | 
 | Hypothyroidism | 
Fatigue caused by reduced thyroid hormone production.Associated symptoms: weight gain, cold intolerance, dry skin, constipation. | 
Thyroid function tests (TSH, free T4) | 
Thyroid hormone replacement (Levothyroxine) | 
 | Chronic Fatigue Syndrome (CFS) | 
Persistent, unexplained fatigue lasting more than 6 months.Associated symptoms: muscle aches, joint pain, headaches, cognitive difficulties. | 
Diagnosis of exclusion—rule out other causes of fatigueNo specific test, may involve blood tests and sleep studies | 
Cognitive behavioral therapy (CBT)Graded exercise therapySymptomatic treatment for pain or sleep disturbances | 
 | Depression | 
Fatigue associated with low mood, lack of motivation, and sleep disturbances.Associated symptoms: feelings of sadness, hopelessness, changes in appetite. | 
Patient history and mental health assessmentQuestionnaires (e.g., PHQ-9) | 
Antidepressant medications (SSRIs, SNRIs)Cognitive behavioral therapy (CBT)Lifestyle modifications and support | 
 | Sleep Apnea | 
Fatigue due to interrupted sleep from airway obstruction during sleep.Associated symptoms: loud snoring, daytime drowsiness, poor concentration. | 
Polysomnography (sleep study) | 
Continuous positive airway pressure (CPAP) therapyWeight loss and lifestyle changesConsider surgery for severe cases | 
 | Diabetes Mellitus | 
Fatigue due to high blood glucose levels or hypoglycemia.Associated symptoms: polyuria, polydipsia, weight loss, blurred vision. | 
Blood glucose levels (fasting, HbA1c) | 
Blood sugar control with insulin or oral hypoglycemic agentsLifestyle modifications (diet and exercise) | 
 | Infections (e.g., Mononucleosis, HIV) | 
Fatigue due to prolonged immune response to infection.Associated symptoms: fever, swollen lymph nodes, sore throat, body aches. | 
Viral serologies (e.g., Epstein-Barr virus, HIV test)CBC to check for lymphocytosis | 
Rest and hydrationAntiviral medications for HIV or other infectionsSymptomatic treatment (e.g., NSAIDs for pain) | 
 | Malignancy | 
Fatigue due to cancer-related inflammation or metabolic effects.Associated symptoms: unexplained weight loss, night sweats, persistent pain. | 
Blood tests (CBC, tumour markers)Imaging studies (CT, MRI)Biopsy for definitive diagnosis | 
Oncological treatment (chemotherapy, radiation, surgery)Supportive care for symptom management | 
 | Heart Failure | 
Fatigue due to reduced cardiac output and poor oxygen delivery to tissues.Associated symptoms: dyspnoea, edema, orthopnea, nocturnal dyspnoea. | 
EchocardiogramBNP (B-type natriuretic peptide) levelsChest X-ray | 
Diuretics, ACE inhibitors, beta-blockersFluid restriction and lifestyle changesManagement of underlying heart conditions |