Development of a standardized pulse-controlled ergometry test for diagnosing and investigating cholinergic urticaria

Abstract

Background: Cholinergic urticaria (CholU) is a common condition in which active or passive warming leads to development of pinpoint wheals, flares and itch.

Objective: To develop a standardized protocol for diagnosing CholU and measuring trigger thresholds, independent of patients' fitness levels.

Method: Ten CholU patients and matched healthy controls underwent pulse-controlled incremental ergometry for 30 min (stationary bicycle) increasing their pulse rate by 15 beats every 5 min. Non-invasive, heat-flux double-sensor and conventional electronic thermometers measured core and skin surface temperatures from which mean body temperature (MBT) was calculated. The time of onset of sweating (starch-iodine test) and symptoms (whealing) were recorded.

Results: All individuals completed the ergometry protocol without difficulty. All CholU patients but no controls developed wheals. The time to whealing correlated inversely with disease severity. In four patients MBT increased <0.5°C and in two whealing occurred at a temperature lower than at the start of exercise. Onset of symptoms correlated with the time of sweating.

Conclusion: Pulse-controlled ergometry is sensitive and specific for diagnosing CholU and investigating trigger thresholds and disease mechanisms. Our results refute the hypothesis that a rise in MBT is the critical trigger for CholU while sweating appears to have the central role.

Keywords: Cholinergic urticaria; Diagnosis; Ergometry; Temperature.