Chronic Fatigue Syndrome (CFS)

Exam Cram

• Chronic Fatigue Syndrome is defined as a persistent & profound fatigue for over 6 months, not relieved by rest or explained by another medical condition

• Previous called: myalgia encephalomyelitis

• Diagnosis: clinical

• Management: holistic approach

Outline

Background

• Chronic Fatigue Syndrome (CFS) prevalence: 1% population

• It is a poorly understood syndrome (collection of symptoms)

Assessment

History

• Global fatigue and reduced exercise tolerance

• Persistent: lasting > 6 months

Examination

• Normal

Investigations

• Normal FBC, urea & electrolytes, calcium/ magnesium / phosphate

Diagnosis

Diagnostic criteria: Institute of Medicine (IOM)- 3/3

• Substantial reduction in ability to engage in pre-illness activities for > 6 months

• Profound fatigue not relieved by rest

• Not explained by another alternative medical conditions 

Differentials: secondary causes (below)- particularly Anaemia, HypoThyroidism, Generalised Anxiety Disorder, Depression

Management

Holistic approach

• Exclude Secondary Causes (see below)

• Education, expectation management, identify triggers

• Mental Health Hygiene- consider CBT

• Sleep Hygiene

• Consider referrals

  • Physiotherapy for graded exercise

  • Chronic Pain

  • Dietitican for dietary advice

Med Reg Notes

Functional disorders

The difficulty with functional disorders is that the diagnosis is purely clinical and currently there are no objective markers. This leads room for stigma and difficulty distinguishing subjective from objective conclusions. 

Secondary Causes

Gradual

• Psychiatric

  • Generalised Anxiety Disorder

  • Depression

  • Insomnia

• Medical

  • Endocrine/ metabolic: Anaemia, HypoThyroidism, HypoCalcaemia & other electrolyte abnormalities, Diabetes Mellitus, Obstructive Sleep Apnea (OSA), Obesity 

  • Organ failure: heart, liver, kidney

  • Weakness: Myasthenia Gravis, Motor Neuron Disease 

  • Chronic infection- parasite, HIV

Acute

• Infective

• Post Traumatic Stress Disorder

• Toxin- carbon monoxide poisoning

Associated Conditions

• Migraine

• IBS

• Chronic Pain

Resources and References

1. https://cks.nice.org.uk/topics/tiredness-fatigue-in-adults/diagnosis/diagnosis-of-cfs/

2. https://www.nhs.uk/conditions/chronic-fatigue-syndrome-cfs/treatment/

Links

• Body systems: musculoskeletal, haematopoetic-immune

• Specialty: GP, rheumatology, psychiatry

Written in 2025