Pruritus is one of the most common problems seen in the office and is one of the most frustrating for patients because much of the time physicians simply treat the symptoms and expect that the pruritus will resolve.  Pruritus is the medical term for itching.  Few symptoms are more annoying than pruritus and when patients present with this symptom they want help.  When we see a patient with pruritus in the office the first issue is to decide if the pruritus is caused by a primary skin condition or not.  When there appears to be a primary skin condition although sometimes these can be very difficult to manage at least as their doctor I can be more comfortable that they don’t have a more serious underlying medical condition causing their pruritus.  This sounds like it should be easy, but this can actually be difficult because the itching itself often leads to scratching and excoriations that lead to skin inflammation, weeping and sometimes secondary skin infections.  Despite this most of the time a good history and examination will allow us to tell if there is a primary skin condition causing the pruritus.  Common skin conditions causing pruritus include irritant or allergic contact dermatitis like poison ivy or industrial irritant dermatitis, atopic dermatitis, skin fungal infections, psoriasis, scabies, dry skin (xerosis), lichen simplex and urticaria (hives).  When we diagnose one of these problems treatment often helps, and usually we can be pretty confident that although the condition may be difficult to clear up we don’t need to worry about serious underlying medical conditions.

Pruritus without a primary dermatologic etiology is definitely more concerning.  When I see pruritus of this type the duration of symptoms and the history and physical exam are the keys to deciding whether to simply treat the itching with medications or to do further diagnostic evaluation.  Pruritus is common enough that if symptoms are only a few days in duration and there are no obvious clues on history suggesting an underlying problem and nothing on a directed physical exam raises red flags treatment with a non-sedating antihistamine like cetirazine (Zyrtec, check Zyrtec side effects) or loratadine (Claritin) is often tried.  If a patient has had symptoms for more that 2-3 weeks usually a lab evaluation looking for diabetes, liver or kidney problems, thyroid disease and hematologic malignancies is done.  About 14-24% of patients that are referred to dermatologists with pruritus without a skin disorder have a systemic condition causing the pruritus.  The list of potential systemic causes is very long but includes:

• Hematologic causes like hemochromatosis, iron deficiency anemia, polycythemia vera and various blood dyscrasias.
• Liver and bile duct problems like cirrhosis, sclerosing cholangitis, drug-induced cholestasis, and viral hepatitis like Hepatitis C.
• Cancers like lymphomas, especially Hodgkin’s Disease, leukemia, multiple myeloma and many solid tumors.
• Endocrine disorders like hypothyroidism, hyperparathyroidism, and diabetes.
• Metabolic disorders like chronic renal disease.
• Neurologic problems like multiple sclerosis, stroke and brain abscesses and tumors.
• Autoimmune disorders like dermatomyositis, Sjogren syndrome, and others.
• Infections like AIDS and parasitic diseases.

If a patient has a normal complete blood count, metabolic profile with a fasting  blood sugar, TSH to exclude thyroid disease, and no primary dermatologic cause often I will get a chest x-ray to check or enlarged lymph nodes in the chest as a clue to lymphoma.  If this is negative I will usually treat their itching for a few weeks.  If they persist with pruritus I may refer them to a dermatologist or an allergist for further evaluation.  Most of the time fortunately no serious causes is found. Still enough of the time they have a  more serious underlying cause that pruritus lasting for more than a few weeks without an apparent cause is a symptom physicians respect and look diligently to solve.