Fatigue

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 * Associate Editor-In-Chief:

Overview
The word fatigue is used in everyday living to describe a range of afflictions, varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles. It can be both physical and mental. Physical fatigue is the inability to continue functioning at the level of one's normal abilities. It is ubiquitous in everyday life, but usually becomes particularly noticeable during heavy exercise. Mental fatigue, on the other hand, rather manifests in somnolence.

Physical fatigue
Physical fatigue or muscle weakness (or "lack of strength") is a direct term for the inability to exert force with ones muscles to the degree that would be expected given the individual's general physical fitness. A test of strength is often used during a diagnosis of a muscular disorder before the etiology can be identified. Such etiology depends on the type of muscle weakness, which can be true or perceived as well as central or peripheral. True weakness is substantial, while perceived rather is a sensation of having to put more effort to do the same task. On the other hand, central muscle weakness is an overall exhaustion of the whole body, while peripheral weakness is an exhaustion of individual muscles.

Mental fatigue
In addition to physical, fatigue also includes mental fatigue, not necessarily including any muscle fatigue. Such a mental fatigue, in turn, can manifest itself both as somnolence (decreased wakefulness) or just as a general decrease of attention, not necessarily including sleepiness. In any case, this can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. For instance, when a person is sufficiently somnolent, he or she may experience microsleeps. However, objective cognitive testing should be done to differentiate the neurocognitive deficits of brain disease from those attributable to tiredness.

Causes
Fatigue is typically the result of working, mental stress, jet lag or active recreation, depression, and also boredom, disease and lack of sleep. It may also have chemical causes, such as poisoning or mineral or vitamin deficiencies.

The sense of fatigue is believed to originate in the reticular activating system of the lower brain. Musculoskeletal structures may have co-evolved with appropriate brain structures so that the complete unit functions together in a constructive and adaptive fashion. The entire systems of muscles, joints, and proprioceptive and kinesthetic functions plus parts of the brain evolve and function together in a unitary way.

Diseases
Temporary fatigue is likely to be e.g. common cold. Chronic fatigue, on the other hand, meaning of six months or more duration, is a symptom of a large number of different diseases on conditions.

Medications

 * Beta blocker medication causes fatigue, especially after exertion, inducing exercise intolerance.

Laboratory Findings

 * Complete blood count (CBC)
 * Chemistries
 * Calcium
 * Urinalysis
 * Glucose
 * Thyroid stimulating hormone
 * Liver function tests
 * Stool guaiac
 * Screening for chronic infection, malignancy, cardiopulmonary disease and psychiatric disease
 * Age-appropriate cancer screening
 * Pregnancy test
 * Appropriate cultures and/or serolgy
 * Lyme titers
 * Hepatitis workup
 * Anemia workup
 * Thyroid function tests

Differential Diagnosis of Causes of Fatigue
(In alphabetical order)


 * 1,3-Dichloropropene
 * 5-MeO-AMT
 * Accessory pancreas
 * Aciclovir
 * Acute bronchitis
 * Acute Hepatitis
 * Acute lymphoblastic leukemia
 * Acute myeloid leukemia
 * Acute prostatitis
 * Acute viral nasopharyngitis (common cold)
 * Adderall
 * Addison's disease
 * Adiposis dolorosa
 * Adrenal metastases
 * African Trypanosomiasis
 * AIDS
 * Airsickness
 * Aldesleukin
 * Altitude sickness
 * Altretamine
 * Amikacin Sulfate Injection
 * Amiloride and Hydrochlorothiazide
 * Andropause
 * Anemia
 * Angina pectoris
 * Ankylosing spondylitis
 * Anorexia Nervosa
 * Anxiety disorder
 * Arnold-Chiari malformation
 * Ascites
 * Atrial fibrillation
 * Auranofin
 * Autoimmune disease
 * Azelastine
 * Azotemia
 * B12 Deficiency
 * Bacterial pneumonia
 * Barbiturate
 * Barth syndrome
 * Becker's muscular dystrophy
 * Benign fasciculation syndrome
 * Beta-blockers
 * Bezafibrate
 * Bipolar disorder
 * Blastocystosis
 * Blood transfusion
 * Botulism
 * Brain abscess
 * Bromopride
 * Bulimia nervosa
 * Busulfan
 * Cadmium
 * Cancer Syndrome
 * Carbon monoxide poisoning
 * Carboplatin
 * Cardiac amyloidosis
 * Cardiogenic shock
 * Carmustine
 * Celiac disease
 * Cerebrovascular arteriosclerosis
 * Cerivastatin
 * Cervical cancer
 * Chlorambucil
 * Chloropyramine
 * Cholesterol pericarditis
 * Chronic bronchitis
 * Chronic Fatigue Syndrome
 * Chronic inflammatory demyelinating polyneuropathy
 * Chronic kidney disease
 * Chronic Liver Disease
 * Chronic mountain sickness
 * Chronic myelogenous leukemia
 * Chronic obstructive pulmonary disease
 * Chronic pancreatitis
 * Chronic pyelonephritis
 * Chronic renal failure
 * Ciguatera
 * Cirrhosis
 * Citalopram
 * Citrulline
 * Citrus
 * Cladosporium
 * Cladribine
 * Clinical depression
 * Clobenzorex
 * Clomipramine
 * Clonidine
 * Coccidioidomycosis
 * Cogan syndrome
 * Congenital Heart Disease
 * Congestive Heart Failure
 * Connective Tissue Disease
 * Conn's Syndrome
 * Constrictive pericarditis
 * Conversion disorder
 * Coronary Artery Disease
 * Coronary Artery Fistula
 * Crohn's disease
 * Cushing's Disease
 * Cytarabine
 * Da Costa's syndrome
 * Dacarbazine
 * Dantrolene Oral


 * Daunorubicin
 * Decompression sickness
 * Dehydration
 * Delavirdine
 * Depo-Provera
 * Diabetes mellitus
 * Diabulimia
 * Diborane
 * Dientamoebiasis
 * Diflunisal
 * Diphtheria
 * Dobutamine Hydrochloride Injection
 * Docetaxel
 * Double Outlet Right Ventricle
 * Doxepin
 * Doxorubicin
 * Duchenne muscular dystrophy
 * Duloxetine
 * Ebola hemorrhagic fever
 * Emergency contraception
 * Emotional exhaustion
 * Emphysema
 * Empty sella syndrome
 * Encephalomyelitis
 * Endometriosis
 * Engelmann syndrome
 * Entamoeba histolytica
 * Enterovirus
 * Epidermolysis bullosa dystrophica
 * Epstein-Barr virus
 * Erysipelas
 * Ethylene
 * Etoposide Oral and Injection
 * Evans syndrome
 * Exertion
 * Ezetimibe/simvastatin
 * Fabry's disease
 * Fairbanks disease
 * Fenofibrate
 * fever
 * Fibromyalgia
 * Floxuridine
 * Fluconazole Injection
 * Fludarabine Phosphate
 * Fluorouracil
 * Fungemia
 * Gastric dumping syndrome
 * Gastric lymphoma
 * Gastroenteritis
 * Gastrointestinal bleeding (GI)
 * Gaucher's disease
 * Gemcitabine Hydrochloride
 * Generalized anxiety disorder
 * Gentamicin Sulfate Injection
 * Gestational diabetes
 * Giant Cell Arteritis
 * Gitelman syndrome
 * Graves' Disease
 * Grifulvin V
 * Griseofulvin
 * Guanfacine
 * Gulf War syndrome
 * H1 antihistamine
 * Hairy cell leukemia
 * Hangover
 * Hantavirus pulmonary syndrome
 * Hashimoto's thyroiditis
 * Hay fever
 * Helicobacter pylori infection
 * Hemochromatosis
 * Hemolytic anemia
 * Hemorrhagic fever with renal syndrome
 * Hepatitis A
 * Hepatitis C
 * Hereditary elliptocytosis
 * Hereditary spherocytosis
 * Herpes simplex virus
 * HIV
 * Hodgkin's lymphoma
 * Hookworm
 * Hydrogen sulfide
 * Hyperaldosteronism
 * Hypercalcemia
 * Hyperglycemia
 * Hypermobility
 * Hyperparathyroidism
 * Hypertensive heart disease
 * Hyperthyroidism
 * Hypertrophic cardiomyopathy
 * Hypervitaminosis D
 * Hypocalcemia
 * Hypoglycemia
 * Hypogonadism
 * Hypokalemia
 * Hypopituitarism
 * Hypotension
 * Hypothyroidism
 * Idarubicin
 * Ifosfamide
 * Inappropriate sinus tachycardia
 * Indapamide
 * Infectious mononucleosis
 * Infective endocarditis
 * Inflammatory Bowel Disease


 * Influenza
 * Interferon Alfa-2a and Alfa-2b Injection
 * Interferon Gamma-1b Injection
 * Interstitial nephritis
 * Irritable bowel syndrome
 * Itraconazole
 * Kikuchi disease
 * Labetalol
 * Lamivudine
 * Lamotrigine
 * Lassa fever
 * Lead poisoning
 * Leukemia
 * Levocetirizine
 * Lomustine
 * Loperamide
 * Low-carbohydrate diet
 * Lower respiratory tract infection
 * Lung cancer
 * Lyme disease
 * Lymphoma
 * Major Depression
 * Malignancy
 * Maprotiline
 * Marburg hemorrhagic fever
 * Marfan syndrome
 * Mechlorethamine
 * Megaloblastic Anemias
 * Meloxicam
 * Melphalan
 * Mercaptopurine
 * Meropenem Injection
 * Mesna
 * Mesothelioma
 * Metal fume fever
 * Methemoglobinemia
 * Methotrexate Injection
 * Metoclopramide Hydrochloride Injection
 * Mifepristone
 * Migraine
 * Milk-alkali syndrome
 * Mitomycin
 * Mitral Stenosis
 * Mitral valve prolapse
 * Molybdenum
 * Monocrotophos
 * Motion sickness
 * Moxonidine
 * Multiple endocrine neoplasia type 1
 * Multiple endocrine neoplasia type 2
 * Multiple myeloma
 * Multiple sclerosis
 * Mushroom poisoning
 * Myasthenia gravis
 * Mycobacterium avium complex infection
 * Mycophenolic acid
 * Myelodysplastic Syndrome
 * Myleofibrosis
 * Myoadenylate deaminase deficiency
 * Myocardial infarction
 * Myofascial pain syndrome
 * Nadolol
 * Naphthalene
 * Nebivolol
 * Neisseria meningitidis
 * Neuroblastoma
 * Neuroglycopenia
 * Neuromuscular weakness
 * Nitrazepam
 * Non-24-hour sleep-wake syndrome
 * Noncompaction cardiomyopathy
 * Non-Hodgkin lymphoma
 * Osteitis fibrosa cystica
 * Osteomalacia
 * Osteomyelitis
 * Ovarian cancer
 * Ovarian cyst
 * Oxaliplatin
 * Oxcarbazepine
 * Paclitaxel
 * Panniculitis
 * Pantothenic acid
 * Parkinson's disease
 * Pegaspargase
 * Pentamidine Inhalation
 * Pentostatin
 * Pericardial constriction
 * Perimenopause
 * Perindopril
 * Pernicious anemia
 * Phenelzine
 * Phlegmon
 * Pityriasis rosea
 * Plicamycin
 * Pneumonia
 * Polyarteritis nodosa
 * Polycystic kidney disease
 * Polycythemia Vera
 * Polymyalgia Rheumatica
 * Polymyositis
 * Post-concussion syndrome
 * Postnatal depression
 * Post-polio syndrome
 * Postural orthostatic tachycardia syndrome


 * Post-viral fatigue syndrome
 * Praziquantel
 * Pregnancy
 * Premenstrual syndrome
 * Primary biliary cirrhosis
 * Procarbazine
 * Promethazine
 * Pseudomembranous colitis
 * Psychosomatic illness
 * Pulmonary hypertension
 * Pure autonomic failure
 * Pyruvate carboxylase deficiency
 * Quinapril
 * Quinidine Oral
 * Radafaxine
 * Radiation poisoning
 * Reactive hypoglycemia
 * Reserpine
 * Respiratory acidosis
 * Respiratory failure
 * Rhinovirus
 * Rifabutin
 * Right Ventricular Outflow Tract Obstruction
 * Rilmenidine
 * Rizatriptan
 * Ross River Fever
 * Sarcoidosis
 * Sargramostim injection
 * Satratoxin-H
 * Scarlet fever
 * Schistosomiasis
 * Sheehan's Syndrome
 * Shock (medical)
 * Short bowel syndrome
 * Sick building syndrome
 * Sick sinus syndrome
 * Sickle-cell disease
 * Silicosis
 * Sinusitis
 * Sjogren's Syndrome
 * Sleep deprivation
 * Sleep disorder
 * Sleeping sickness
 * SSRI discontinuation syndrome
 * ST Elevation Myocardial Infarction Symptoms
 * Starvation
 * Still's disease
 * Stomach cancer
 * Streptozocin
 * Stress (medicine)
 * Subacute bacterial endocarditis
 * Syphillis
 * Systemic lupus erythematosus
 * Takayasu's arteritis
 * Temozolomide
 * Teniposide
 * Terazosin
 * Thalidomide
 * Thiabendazole
 * thiazide
 * Thioguanine
 * Thiotepa
 * Thrombotic Thrombocytopenic Purpura
 * Tinidazole
 * Tobramycin Sulfate Injection
 * Tolosa-Hunt syndrome
 * Topiramate
 * Topotecan Hydrochloride
 * Torsemide Injection
 * Torsemide Oral
 * Tralomethrin
 * Trandolapril
 * Trastuzumab
 * Trazodone
 * Trepanation
 * Trestolone
 * Tricuspid Regurgitation
 * Trifascicular block
 * Trimetrexate Glucuronate
 * Trovafloxacin
 * Tuberculosis
 * Tularemia
 * Ulcerative colitis
 * Upper Airway Resistance Syndrome (UARS)
 * Urinary tract infection
 * Valaciclovir
 * Valproic acid
 * Valvular Heart Disease
 * Venlafaxine
 * Ventricular Septal Defect
 * Vicodin
 * Vigabatrin
 * Vinblastine
 * Vinorelbine Tartrate
 * Viral Hemorrhagic Fever
 * Vitamin C megadosage
 * Wegener's granulomatosis
 * Wolff-Parkinson-White Syndrome
 * Zalcitabine
 * Zidovudine Injection
 * Zileuton
 * Zoledronate
 * Zopiclone

Complete Differential Diagnosis of the Causes of fatigue
(By organ system)

Treatment

 * Treatment of underlying medical etiologies
 * Discontinue (or switch) harmful/aggravating medications
 * Schedule regular physical activity
 * Improvement of sleep hygiene
 * Cognitive behavioral psychiatric therapy
 * Referral to possible support groups
 * Weight loss (for obesity)
 * Supportive care, healthy diet, moderate exercise (chronic fatigue syndrome and fibromyalgia)

Acute Pharmacotherapies

 * Antidepressants