A new cold test for the diagnosis of Raynaud's phenomenon

An objective test for the diagnosis of Raynaud's phenomenon is useful for three reasons: 1. the phenomenon may not be evident at the time of the clinical examination, 2. proof of diagnosis is required by insurance companies when an occupational origin is suspected, and 3. to assess drug induced improvement. Most cold tests in the medical literature are either complex and expensive or unreliable for routine clinical use. We studied cold induced post-ischemic reactive hyperemia in 14 patients with Raynaud's disease and in 15 healthy controls. The hand was immersed in a stirred water bath at 13 degrees C, and ischemia was induced by placing an inflatable tourniquet around a finger for five minutes. Afterwards the tourniquet was deflated while the hand remained in the cold water bath. The temperature of the finger with the deflated tourniquet was compared with that of an adjacent finger serving as control. Hyperemia was the increase in differential temperature between these two fingers after tourniquet release minus the difference in temperature existing before deflating the tourniquet. With a normal lower limit of 0.7 degrees C for hyperemia, 13 of the 14 patients with Raynaud's phenomenon were abnormal (93% sensitivity), and 14 of the 15 controls were normal (93% specificity). All these 14 controls were also normal at a second examination done to assess test reproducibility. A false-positive healthy control was still positive at the second examination. This new, simple and inexpensive cold test can reliably diagnose Raynaud's phenomenon. Further studies are necessary to establish its reliability in monitoring the effectiveness of treatment in prospective trials.