Causes of Generalized Itching Without Skin Rash
Itchy Skin Sans Rashes or Pruritus Sine Materia
Aug 23, 2009
Finding the causes of generalized itching in the presence of skin rashes is comparatively easy as the underlying condition is clinically evident. But finding the cause for generalized itching without any visible skin rash (except maybe scratch marks) requires extensive history taking and clinical and laboratory examination of various body systems.
Most of the time, the diagnosis is made through a process of exclusion - by reviewing and excluding the most important causes of generalized pruritus. Itching is caused by the action of histamine and other chemical mediators released by mast cells following a variety of triggering events in the body.
Common Causes of Generalized Itchy Skin With No Visible Rash
The generalized itching may be manifestation of an underlying systemic disease, a skin disease in its early stage, a drug or food sensitivity, infections or even psychogenic. Persistent, intense and intractable itching can be maddening for the patient as most of the time anti-itch medications will have no effect on the itching. Finding and eliminating the specific cause of the generalized pruritus is the only way to alleviate the suffering of the patient.
Generalized Pruritus Caused by Kidney Failure
In more than 50% of chronic kidney disease, itching is a prominent symptom. Intense scratching can produce skin rashes and lead to secondary skin changes as seen in prurigo nodularis, nummular eczema or lichen simplex chronicus. The itching is caused by toxins accumulating within the body due to inadequate clearance by the kidneys.
Liver Diseases with Obstruction to the Bile Flow (Cholestasis) Cause Distressing Generalized Itching
The itching in obstructive liver diseases may start as itchy palms and soles, later spreading to other parts of the body. The itchingof hepatic diseaseis due to the bile salts and elevated levels of opioid peptides in the blood and skin.
Hormonal Problems as a Cause for Generalized Itching
Intense itching can be a feature of both over and under activity of the thyroid hormones. In hyperthyroidism, the itching is due to the increased blood flow and metabolic activities, while dryness is the main cause for itching in hypothyroidism. The systemic and metabolic changes causes generalized itching in pregnancy, especially in the later half. Itching is an early manifestation of diabetic neuropathy. Certain hormone secreting tumors within the gastrointestinal system can also be a cause of generalized pruritus.
Blood Disorders and Malignancies Causing Generalized Pruritus
More than half of polycythemia vera patients experience intense generalized itching, especially after contact with water. This is known as bath itch or aquagenic pruritus. In Hodgkin’s lymphoma, generalized itching is usually the presenting symptom.
In leukemias and other lymphomas also severe itching of the skin with or without identifiable skin rashes is a major complaint. In mastocytosis without skin lesions, severe itching follows rubbing of the skin. This is due to excess release of histamine. Itching is also a major symptom in multiple myeloma. Iron deficiency anemia can cause intractable itching on the skin.
Generalized Itching in HIV Infection
Intense generalized itching with or without skin rash is a common primary symptom of HIV infection and AIDS.
Infestations Causing Generalized Itching
Scabies in its early stages can cause intense itching, especially during night without any evident skin lesions. Head and body lice infestations, intestinal worm infestations like hookworm, round worm and onchocerciasis etc. can also cause intense generalized itching.
Drugs and Food Can Cause Generalized Pruritus Sine Rash
The first suspect of any itching followed by a drug or food ingestion is indeed the ingested or injected agent.
Psychogenic Causes of Generalized Itching
Emotional stress, delusions of parasitosis, depressive illness all can cause generalized itching without any skin rashes.
Latent Skin Diseases or Early Stages of Dermatoses Causing Itchy Skin
Dry skin, aged skin, bullous pemphigoid, dermatitis herpetiformis, atopic dermatitis, contact allergies, fiberglas exposure etc. can cause generalized pruritus.
Thus a careful history and physical examination taking into account the different types of itching, their duration, character, timing and distribution are essential to find out the exact causes of generalized itching without skin rashes. Systemic causes of generalized itching are to be considered only after ruling out the common skin diseases in their latent or early stages. Correct diagnosis will help in proper treatment of the itchy skin problem.
Reference
- Pruritus, in Rook’s Textbook of Dermatology, 7th Edition, 2004
- Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, Fifth Ed, 2005
Disclaimer
The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.
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