Investigations

On the whole, diagnosis is usually made through clinical observation. Particularly for ordinary urticaria there is usually no need to perform any specific investigatory tests. However in acute and episodic cases allergic responses may be verified using skin prick tests and CAP fluoroimmunoassay tests on blood. If patients with chronic ordinary urticaria are not responding to antihistamines, it may be helpful to determine whether there are other autoimmune conditions present, e.g. check thyroid function. Long- standing urticaria that is not responding to treatment may be biopsied to identify whether there is a vasculitis present (Gittins, 2008).