Fatigue

1.  Define “Fatigue” — Distinguish from other symptoms, esp. true “weakness”:

• “Weakness” = Neurologic diseases, rare but possibly very serious.  Patient may fall, or drop things. Identified by finding actual muscle weakness when testing patient’s strength
• “Fatigue” = feeling worn out, but muscle strength is normal when tested
• Shortness of Breath = Heart or Lung disease.  Suspected if patient feels they “huff & puff” with simple exertion
• Sleepiness = nodding off in daytime, suggests Sleep Apnea or Narcolepsy
• “Aches” suggest muscle disease like fibromyalgia, or more serious conditions. See Body Aches

2.  Define Time Frame:

• Acute Fatigue  =  ≤1 month (more concerning)
• Chronic Fatigue  =  >6 months (unlikely to be dangerous)
• If 2-6 months  =  “Acute” if getting worse; “Chronic” if staying the same

3.  Consider Possible Diagnoses

• Acute Fatigue, <1-2 weeks, we’d think Viral Infection (could include Covid-19), also Anxiety, Depression
  • Every setting has its own way to address Covid before letting a patient in the door. The rest of this topic assumes we’re not dealing with it.
• Acute Fatigue, going on 2-4 wks: statistically, most likely Anxiety or Depression, but we begin to consider other causes in the table below
  • If other prominent symptoms, we work off of them to seek diagnosis (e.g. Cough, Fever, Diarrhea, Body Aches)

Causes of “Fatigue” as the Main Symptom

xxxxxxINFECTIONS • Heart (a low-grade one) ** • Simple Virus ** • Bacterial (one that’s not xxxobvious)** • Mononucleosis ** • HIV • Hepatitis (acute or chronic) • Tuberculosis • Other IDIOPATHIC (Unknown Cause) • Chronic Fatigue Syndrome (whether meets the CFS case-definition or not) x

xxxMETABOLIC DISORDERS   • Blood Abnormalities xxxsodium, potassium, xxxcalcium, etc. ** • Kidney Failure • Liver Failure: acute / chronic xxxENDOCRINE DISEASES   • Diabetes • Hypothyroidism • Hyperthyroidism • Adrenal Insufficiency • Pituitary Insufficiency    **  Not likely once symptom has become Chronic

xxxxxxxOTHER   • Cancer (various) ** • Depression • Anxiety • Drugs / Alcohol / Medicines • Drug Withdrawal • Anemia (mod.-severe) • Celiac Disease • Malnutrition • Rheumatologic disorders xxx(see Joint Pain) • Any Chronic Condition that’s xxbothersome (stomach acid, xxallergies, etc.) x x x

4.  Think about possible Red Flags 

May be serious (e.g. cancer), get CT Scans if no diagnosis from basic lab tests (below):

• Fevers (ongoing)
• Night Sweats (drenching)
• Weight Loss

5.  Some Possible Lab Tests if no clear diagnosis from History & Physical Exam:

• Complete Blood Count (CBC) (for Infections, Anemia)
• Comprehensive Metabolic Panel (CMP) (for Metabolic Disorders (low / high sodium, potassium, calcium); Hepatitis; Kidney Failure; Liver Failure (Acute / Chronic); Diabetes (new)
• Thyroid Stimulating Hormone (TSH) (for Thyroid Diseases)
• Urinalysis for Infections
• Erythrocyte Sedimentation Rate (“sed rate”) &/or C-Reactive Protein (ESR or CRP)
• HIV Test for HIV
• Monospot (blood test for Mononucleosis) [only for younger patient with <1 month of symptoms]
• Only if muscle aches are present, a Creatinine Kinase for Muscle Diseases
• Maybe also a Chest X-Ray for Lung infections
• If chronic diarrhea or bloating, maybe a tissue-Transglutaminase (blood test for Celiac Disease)
• If dizziness & fall in blood pressure upon standing (see postural vital signs), maybe obtain a blood cortisol level for rare Adrenal Insufficiency

6.  Patient returns in 3 weeks  → review labs and Check Weight

• Pursue any significant lab abnormalities
• If significant weight loss, needs CT Scans chest, abdomen, pelvis, & more work-up

7. No Weight Loss & All Tests Normal (No Red Flags)

• Depression or Anxiety are most likely diagnoses, often due to personal stressors.  Treat these if any possibility
  • If Depression, essential to exclude thoughts of suicide
• Essential to exclude possible Domestic Violence (esp. for vulnerable persons)
• Chronic Fatigue Syndrome is default diagnosis of exclusion (nothing else), symptoms often lasting many months
• Ongoing follow-up to be sure no Red Flags develop, no new symptoms needing work-up

See Fatigue — Full Text for more in-depth explanations and discussions.