The diagnosis of hives (urticaria) is one of exclusion. It is essential to first rule out the presence of a serious illness of which hives can be a symptom (such as thyroid disease, hepatitis, lupus [systemic lupus erythematosus], or some types of cancer). After ruling out an underlying serious illness, identifying the trigger factor or source of hives is essential.
Your Medical History
Every diagnosis begins with a detailed medical history. The doctor will ask lots of questions about the nature of the reaction, where and when it occurs, and whether the hives seem to be associated with a particular substance or event. The patient may be asked to keep a detailed diary recording outbreaks, foods eaten, drugs taken, environmental factors and activities. Questions about work are also important because many occupations can be associated with hives. Since allergy may be genetic, expect some questions about other family members who may be allergic.
Depending on your history, different blood tests or skin tests may be performed. The number of tests performed is determined after your doctor obtains your history. Occasionally for physical urticaria, tests such as exercise study or ice cube challenge may be recommended.