Question: How to diagnose Cold urticaria ?
Answer: How is cold urticaria diagnosed? A diagnosis of cold urticaria is typically suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to confirm the diagnosis and determine if there are other associated conditions. This generally involves a cold simulation test in which a cold object (such as an ice cube) is applied against the skin of the forearm for 1-5 minutes. In people affected by cold urticaria, a distinct red and swollen rash will generally develop within minutes of exposure. A complete blood count and/or metabolic tests may also be performed to determine associated diseases.
Source: GARD