II. Definitions

  1. Pruritus
    1. Unpleasant cutaneous Sensation (itch) provoking scratching

III. Epidemiology

  1. Among the most common dermatologic symptoms
  2. Very common in elderly patients

IV. Pathophysiology

  1. Nerve fiber involvement
    1. Origin of itch is within skin Free Nerve Endings
      1. Fibers most concentrated in wrists and ankles
      2. Unmyelinated C fibers to dorsal horn in spinal cord
    2. Scratching is a spinal reflex response
    3. Ascends to cerebral cortex via Spinothalamic Tract
  2. Chemical mediators
    1. Substance P
    2. Opioid and nonopioid peptides
    3. Somatostatin
    4. Neurokinin A
    5. Histamine
    6. Serotonin
    7. Prostaglandins
  3. External mediators
    1. Skin inflammation
    2. Environmental heat or dryness
    3. Vasodilation
    4. Psychological concerns

V. Causes

VI. Types: Chronic Pruritus Classification Groups

  1. Group 1: Pruritis on Diseased Skin
    1. Dermatologic causes
  2. Group 2: Pruritus on Non-Diseased Skin
    1. Systemic, neurogenic or psychogenic causes
  3. Group 3: Chronic reactive lesions from skin manipulation (rubbing, picking, scratching)
    1. Mixed presentations and complications from primary condition

VII. Evaluation

  1. Identify primary Dermatologic Causes of Pruritus
    1. Atopic Dermatitis: Atopy, Asthma, or Urticaria
    2. Contagious contacts (Pediculosis or Scabies)
    3. Pathognomonic skin lesions (e.g. Psoriasis, Eczematous Dermatitis, Dermatophytosis)
    4. Consider Localized Causes of Pruritus
    5. Consider Timing (Xerotic Eczema worse in winter)
  2. Identify potential exposures
    1. See Medication Causes of Pruritus
    2. Travel history and new animal exposures (fleas, Scabies, Dermatophytosis)
    3. Contagious Contacts (e.g. Parvovirus B19, Varicella)
    4. Consider Environmental Causes of Pruritus (e.g. solvents, cleaners, adhesives)
      1. See Allergic Contact Dermatitis
      2. See Occupational Contact Dermatitis
      3. See Irritant Contact Dermatitis
      4. Ask about new skin or hair products (e.g. soaps, lotions, detergents, cosmetics)
      5. Consider Photodermatitis
  3. Review mental health concerns (e.g. Major Depression)
  4. Consider Systemic Causes of Pruritus
    1. Observe for cholestasis (e.g. Jaundice, Hepatomegaly)
    2. Consider Renal Failure Associated Pruritus (e.g. Nausea, decreased Urine Output, Fatigue)
    3. Consider Thyroid disease (esp. Hyperthyroidism)
    4. Consider malignancy (e.g. Night Sweats, weight loss, Fatigue, Lymphadenopathy)

VIII. Labs: Evaluation

  1. Approach
    1. Base lab testing on history and physical
    2. Avoid broad shotgun approach to lab testing
    3. Consider lab testing in >2 weeks of persistent Pruritus without other obvious causes
  2. Dermatologic Cause Evaluation
    1. Skin Scrapings for Scabies and Dermatophytosis
    2. Skin biopsy
      1. Mastocytosis
      2. Mycosis Fungoides
      3. Autoimmune Bullous Disease
  3. Systemic Cause Evaluation (esp. age >65 years, generalized Pruritus, chronic Pruritus >6 weeks)
    1. Thyroid Function Test (evaluate for Hyperthyroidism)
    2. Complete Blood Count (CBC)
    3. Comprehensive Metabolic Panel
      1. Serum Creatinine
      2. Blood Urea Nitrogen (BUN)
      3. Liver Function Tests (evaluate for cholestasis)
        1. Serum Bilirubin
        2. Alkaline Phosphatase
    4. Iron Studies
      1. Serum Ferritin
      2. Serum Iron
      3. Iron binding capacity
    5. Other labs to consider
      1. HIV Test
      2. C-Reactive Protein
      3. Erythrocyte Sedimentation Rate (ESR)

IX. Imaging: Systemic Cause Evaluation

  1. Chest XRay (if Lymphoma suspected)
  2. Right upper quadrant Ultrasound (for cholestasis)

X. Complications: Persistent Scratching

  1. Bacterial superinfection
  2. Prurigo Nodularis
  3. Lichen Simplex Chronicus
    1. Thickened skin in response to repeated scratching

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Related Studies

Ontology: Pruritus (C0033774)

Definition (MSHCZE) Někdy se jako pruritus označuje svědění bez průvodních kožních změn – primární pruritus. Bývá poměrně častý u starších lidí v důsledku stárnutí kůže, ale i jejího přesušení. Provází rovněž některé vnitřní choroby např. městnání žluči při cholestáze, cukrovku, Hodgkinovu nemoc aj. Jako sekundární pruritus se pak označuje svědění provázející kožní nemoci ekzém, mykózy aj. (cit. Velký lékařský slovník online, 2012 http://lekarske.slovniky.cz/ )
Definition (MEDLINEPLUS)

Itching is skin tingling or irritation that makes you want to scratch the itchy area. It's a symptom of many health conditions. Common causes are

To soothe itchy skin, you can try cold compresses, lotions and lukewarm baths. Avoid scratching, wearing irritating fabrics and high heat and humidity. Most itching is not serious. However, if you itch all over, have hives that keep coming back or have itching without an apparent cause, you might require medical attention.

Definition (NCI_NCI-GLOSS) Itching. Severe itching may be a side effect of some cancer treatments and a symptom of some types of cancers.
Definition (NCI) A skin disorder characterized by an intense itching sensation.
Definition (NCI_CTCAE) A disorder characterized by an intense itching sensation.
Definition (NCI) An intense itching sensation.
Definition (MSH) An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief.
Definition (CSP) intense itching sensation that produces the urge to rub or scratch the skin to obtain relief.
Concepts Sign or Symptom (T184)
MSH D011537
ICD9 698.9
ICD10 L29 , L29.9
SnomedCT 424492005, 271588004, 32738000, 78934009, 201371004, 156380008, 201027005, 183758005, 267804004, 367516003, 418363000, 279333002, 418290006
LNC LA20641-9
English Itching, Pruritis, Pruritus, Unspecified pruritic disorder, PRURITIS, PRURITUS, pruritis, Irritation - sensation, Pruritic disorders, Pruritus NOS, Pruritus, unspecified, Skin Pruritus, [X]Pruritus, unspecified, Itch of skin (observable entity), Itch of skin, Irritating sensation, itching (pruritus), pruritus (symptom), pruritus, itching, Pruritus cutaneous, Itchy skin, Pruritic disorder NOS, Itch NOS, Pruritus [Disease/Finding], itching skin, skin itch, itchy, itch skin, skin itching, Itching;skin, Pruritus;skin, itchy skin, pruritic dermatitis, pruritus (diagnosis), Pruritus (finding), Pruritus (disorder), Pruritus of skin (finding), Pruritus NOS (disorder), [X]Pruritus, unspecified (disorder), Scratching skin, ITCHING, Pruritus - disorder, Pruritic dermatitis, Pruritic disorders (disorder), Pruritus of skin, Pruritic disorder, itch, Pruritus, NOS, Itch of skin, NOS, Pruritic dermatitis, NOS, Pruritus of skin, NOS, Pruritus [Ambiguous], Pruritus [dup] (finding), Pruritus of skin (finding) [Ambiguous], Pruritic Disorder, pruritis of skin, Itch, Itchy, Itching (finding), Itching of skin (finding), Itching of skin
French PRURIT, Affection prurigineuse non précisée, Prurit cutané, Prurit SAI, Démangeaisons, Démangeaison de la peau, Avec démangeaisons, DEMANGEAISONS, Prurit, Démangeaison
Portuguese PRURIDO, Afecção pruriginosa NE, Pele pruriginosa, Pruriginoso, Prurido cutâneo, Prurido NE, PRURIDO (COCEIRA), Prurido, Coceira
Spanish PRURITO, prurito (hallazgo), prurito cutáneo (hallazgo), prurito cutáneo, prurito, picazón, Comezón, Picor, Prurito NEOM, Prurito cutáneo, Trastorno prurítico no especificado, Picor en piel, prurito cutáneo (entidad observable), picazón de la piel, PICOR, prurito de la piel, [X]prurito, no especificado, prurito, SAI (trastorno), escozor, prurito, SAI, dermatitis pruriginosa, prurito cutáneo, SAI, [X]prurito, no especificado (trastorno), prurito de la piel (hallazgo), prurito de la piel (concepto no activo), dermatitis pruriginosas, enfermedades pruriginosas, picar, prurito cutáneo (trastorno), enfermedad pruriginosa, trastorno pruriginoso (trastorno), trastorno pruriginoso, trastornos pruriginosos de la piel, Prurito, Picazón
Dutch pruritus NAO, jeuk, jeuken, jeukende huid, niet-gespecificeerde pruritus, pruritus cutaneus, jeukend, Pruritus, niet gespecificeerd, pruritus, Jeuk, Pruritus
German Pruritis kutan, unspezifische von Jucken begleitete Stoerungen, Pruritis, Jucken, juckende haut, Pruritus NNB, juckend, HAUTJUCKEN, JUCKREIZ, Pruritus, nicht naeher bezeichnet, Hautjucken, Pruritus
Italian Prurito cutaneo, Cute pruriginosa, Prurigine, Prurito NAS, Pizzicore, Sensazione di prurito, Affezioni pruriginose non specificate, Pruriginoso, Pruritus, Prurito
Japanese そう痒症NOS, 皮膚そう痒, 詳細不明のそう痒性疾患, ソウヨウ, ヒフソウヨウショウ, ソウヨウショウNOS, ヒフソウヨウ, ソウヨウショウ, ショウサイフメイノソウヨウセイシッカン, そう痒症, かゆみ, そうよう, そう痒, 掻痒, 痒み, 皮膚そう痒症, かゆみ症
Swedish Klåda
Czech pruritus, svědění, Svědící, Svědění, Svědění kůže, Pruritus NOS, Pruritus, Blíže neurčené svědivé poruchy
Finnish Kutina
Russian ZUD, ЗУД
Korean 상세불명의 가려움, 가려움
Croatian PRURITUS
Polish Świąd
Hungarian Nem meghatározott viszkető betegség, Viszkető bőr, Viszketés, Viszketegség, Viszket, pruritus, Viszkető, bőrviszketés, Viszketés k.m.n.
Norwegian Pruritus, Kløe