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Tests and diagnosis
By Mayo Clinic staff
Physical exam and other tests
Your doctor is likely to first conduct a physical exam to see if a cause for your itching can be determined.
If your doctor suspects that your itchy skin is the result of an underlying medical condition, he or she may perform other tests, such as a:
- Blood test. A complete blood count can provide evidence of an internal condition causing your itch, such as iron deficiency.
- Chemistry profile. This test is used to determine if you have a liver or kidney disorder, which could cause itchy skin.
- Thyroid function test. Thyroid abnormalities, such as hyperthyroidism, may cause itching.
- Chest x-rays. Signs of underlying disease that are associated with itchy skin, such as enlarged lymph nodes, can be seen by using radiography.
Related conditions
Through examination and tests, your doctor may determine that your itching is, in fact, a symptom of another skin condition. Related itchy skin conditions include:
- Dermatitis. Also called eczema, dermatitis is an inflammation of the skin. There are different types of dermatitis, and the disorder can have many causes and occur in many forms. The most common type of eczema is atopic dermatitis. Generally, dermatitis describes swollen, reddened and itchy skin.
- Psoriasis. With psoriasis, the life cycle of skin cells speeds up, resulting in a rapid buildup of rough, dead skin cells. These skin cells accumulate, forming thick silvery scales and itchy, dry, red patches that are sometimes painful.
- Tinea infections. Athlete's foot, ringworm of the body, ringworm of the scalp and jock itch are caused by a fungal infection that develops on the top layer of your skin. These infections often cause round, flat patches of itchy skin.
- Hives. Hives are raised, itchy red bumps of various sizes that appear and disappear on your skin. Allergic reactions to medications or foods can cause hives. Skin writing (dermatographism) is a condition where stroking the skin causes hive-like lesions to develop in the touched areas.
- Lice. Body lice, pubic lice and head lice are common causes of intense itching. Lice are tiny, wingless, parasitic insects that feed on your blood. The infestation, which is easily spread through close physical contact, can cause small, red bumps.
- Scabies. Scabies is caused by a tiny, eight-legged burrowing mite called Sarcoptes scabiei. The presence of the mite leads to intense itching in the area of its burrows. Scabies is contagious and can spread quickly through close physical contact.
References
- Cassano N, et al. Chronic pruritus in the absence of specific skin disease. American Journal of Clinical Dermatology. 2010;11:399.
- Yosipovitch G, et al. Pathophysiology and clinical aspects of pruritus: Introduction. In: Wolf K, et al. Fitzpatrick's Dermatology in General Medicine. 7th ed. New York, N.Y.: The McGraw-Hill Companies. 2008. http://www.accessmedicine.com/content.aspx?aID=2960463&searchStr=pruritus#2960463. Accessed Oct. 26, 2010.
- Pruritus. American Academy of Dermatology. http://www.aad.org/public/publications/pamphlets/common_pruritus.html. Accessed Oct. 26, 2010.
- Fazio SB. Pruritus. http://www.uptodate.com/home/index.html. Accessed Oct. 26, 2010.
- Metz M, et al. Chronic pruritus - Pathogenesis, clinical aspects and treatment. Journal of the European Academy of Dermatology and Venereology. 2010;24:1249.
- Berger TG. Dermatologic disorders. In: McPhee SJ, et al. Current Medical Diagnosis and Treatment. 50th ed. New York, N.Y.: The McGraw-Hill Companies. 2011. http://www.accessmedicine.com/content.aspx?aID=747&searchStr=pruritus#1682. Accessed Oct. 26, 2010.
- Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 8, 2010.
- Benzocaine topical products: Sprays, gels and liquids — risk of methemoglobinemia. U.S. Food and Drug Administration. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm250264.htm. Accessed Apr. 8, 2011.
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