Normative Values for Sudomotor Axon Reflex Testing using QSWEAT™ (P1.282)

OBJECTIVE: To establish normative values for QSWEAT™ in a large volunteer cohort. BACKGROUND: The indirect sudomotor response to iontophoresis of acetylcholine provides valuable information about the integrity of postganglionic sudomotor fibers. This methodology has been used for many years as Quantitative Sudomotor Axon Reflex Test (QSART) using proprietary equipment. A commercially available device (QSWEAT™) is now widely used in autonomic laboratories. Studies have shown that QSART- and QSWEAT™-derived sweat volumes - although strongly correlated - differ in magnitude. Previously reported normative values for QSART are therefore not suitable for QSWEAT™. DESIGN/METHODS: Over 400 healthy volunteers were recruited at the University of Hawaii and Mayo Clinic Rochester. All subjects underwent routine autonomic function testing using standardized environmental and skin temperature control. Acetylcholine (10[percnt] solution/gel) was iontophoresed into skin at four standardized sites. The evoked sweat response was measured using QSWEAT™ equipment. RESULTS: The sweat response distribution revealed increasing sweat volumes with age until a stable plateau was reached by age 20 with again decreasing sweat volumes beyond age 70. We therefore combined the data of subjects between ages 20 and 69 years for percentile calculations of adult normative values. Data of the young (≤19) and elderly (蠅70) were analyzed separately. 376 volunteers fell in the age range 20-69 years (men=148, women=228). Sweat volumes were significantly lower in women, but there was no significant difference by study site. The 5th percentiles of normal in the adult age range were (female/male): Forearm: 0.08/0.25; Proximal Leg: 0.19/0.48; Distal Leg: 0.14/0.62; Foot: 0.07/0.15mcl. CONCLUSIONS: We present normative values and suggested cut-offs of normal for sudomotor testing using QSWEAT™. Sweat volumes plateaued between ages 20-69, and were as expected markedly lower in women. Inspite of climate and racial differences, sweat volumes were not different between study sites. Supported by NIH (P01NS44233, U54NS065736, K23NS075141, UL1RR24150), Mayo Funds. Disclosure: Dr. Sletten has nothing to disclose. Dr. Grandinetti has nothing to disclose. Dr. Weigand has nothing to disclose. Dr. Gehrking has nothing to disclose. Dr. Gehrking has nothing to disclose. Dr. Low has received personal compensation for activities with Chelsea Therapeutics, Pfizer Inc., and WR Medical Electronics Company as a consultant. Dr. Singer has received license fee payments from Jacobus Pharmaceutical.