NHS Choices Condition
Content supplied by NHS Choices
There is no blood test for psoriasis. Usually your doctor will make the diagnosis from the appearance of your affected skin. Rarely, a sample of skin scrapings or a small sample of skin will be sent to the laboratory for examination under a microscope. This will determine the exact type of psoriasis and to rule out other skin disorders such as seborrheic dermatitis, lichen planus, neurodermatitis and pityriasis rosea.
If your doctor suspects you have psoriatic arthritis (see complications), you should be referred to a rheumatologist, who specializes in arthritis. Blood tests may be taken to rule out other conditions and X-rays of the affected joints may be taken.
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