Common Sense Pathology

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Chronic fatigue is defined as unexplained fatigue of greater than or equal to 1 - 3 months duration.

A thorough medical history, physical examination, mental status examination, and laboratory tests must be conducted to identify underlying or contributing conditions that require treatment.



Hepatobiliary disease
Renal disease
Thyroid disease
Bone/parathyroid disorders
Diabetes mellitus
Addison's disease

The above battery of screening tests will exclude most of the relevant disorders

Specific causes not screened for:

Only if clinically indicated, or the initial screening shows a possible infective/ inflammatory process

Epstein Barr virus

EBV serology


Coxsackie B serology


HIV serology

Autoimmune disease

ANF, anti-DNA

Initial laboratory investigations

A minimum battery of laboratory screening tests should be performed and include:

FBC, ESR LFTs U&E Serum calcium Serum phosphate Blood glucose TSH Urinalysis Further tests may be indicated on an individual basis to confirm or exclude another diagnosis e.g. EBV, enteroviruses, HIV etc.

Chronic fatigue syndrome

This is a subset of chronic fatigue, whereby the fatigue is unexplained and last for more than 6 months for which no cause can be found both clinically and by "exclusion" laboratory tests.

The patient also needs to meet the following criteria:

  1. Clinically evaluated, unexplained persistent or relapsing chronic fatigue that is new or of definite onset, is not the result of ongoing exertion, is not alleviated by rest, and results in substantial reduction in previous levels of occupational, educational, social, or personal activities.
  2. The concurrent occurrence of four or more of the following symptoms:
    1. Substantial impairment of short-term memory and concentration.
    2. Sore throat
    3. Tender lymph nodes
    4. Muscle pain
    5. Multi-joint pain without swelling or redness
    6. Headaches of a new type, pattern, or severity
    7. Unrefreshing sleep
    8. Post-exertional malaise lasting more than 24 hours.



1. Mandell, Douglas and Bennett. Principles and Practice of Infectious Diseases 2000; 1529 - 1532

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