A. History: Acute Onset (hours to days)
Differential Diagnosis
Infections (e.g., influenza, COVID-19, mononucleosis), Acute illness or inflammation (e.g., viral hepatitis), Medications or drug withdrawal, Acute anemia (e.g., from blood loss), Psychological stress or trauma, Acute heart failure or cardiac ischemia
| Pivotal Assessment | Finding |
|---|---|
Further History |
Determining the cause of fatigue involves a careful assessment of multiple potential factors. Fatigue can be broadly classified into physiological, psychological, and medical causes. Here's a systematic approach:
Ask about:
Onset and duration (sudden vs gradual, chronic vs acute)
Sleep quality (e.g., insomnia, sleep apnea)
Activity level (overexertion, sedentary lifestyle)
Diet and hydration
Stress, anxiety, or depression
Medications (e.g., antihistamines, beta-blockers, statins)
Substance use (alcohol, caffeine, recreational drugs)
Recent infections or illnesses
Common causes include:
Hypothyroidism
Diabetes (especially if poorly controlled)
Adrenal insufficiency
Electrolyte imbalances
Anemia
Mononucleosis
Hepatitis
HIV
Post-viral fatigue
Heart failure
Coronary artery disease
COPD or sleep apnea
Depression
Anxiety
Chronic stress
Burnout
Chronic kidney disease
Liver disease
Malignancy
Chronic fatigue syndrome / Myalgic encephalomyelitis
Fibromyalgia
Look for:
Pallor (anemia)
Thyroid enlargement or signs of hypothyroidism
Lymphadenopathy (infection or malignancy)
Signs of heart or lung disease
Neurological abnormalities
CBC (anemia, infection)
TSH and free T4 (thyroid function)
CMP (electrolytes, liver/kidney function, glucose)
HbA1c (diabetes control)
Vitamin B12, folate, and iron studies
ESR/CRP (inflammation)
Consider HIV, hepatitis serologies, sleep study if indicated
Evaluate:
Work/life balance
Relationship or caregiving stress
Recent life changes
Substance use
Would you like to go over a specific case or set of symptoms to narrow it down further?