Performing only one cardiovascular reflex test has a high positive predictive value for diagnosing autonomic neuropathy in patients with chronic renal failure on hemodialysis

BACKGROUND: Autonomic neuropathy is an important cause of morbidity and mortality in patients with chronic renal failure (CRF) on hemodialysis. Generally, cardiovascular reflex tests are used to determine autonomic neuropathy. Our purpose in this study was to determine the frequency of autonomic neuropathy in patients with CRF on hemodialysis by using cardiovascular reflex tests and compare the sensitivity of each test. METHODS: The authors performed five tests: heart rate response to the Valsalva maneuver, heart rate variation during deep breathing, heart rate response to standing up, blood pressure response to standing up, and blood pressure response to hand grip exercise in order to determine autonomic neuropathy. Each test subject was evaluated as normal, borderline, and abnormal and scored as 0, 1, and 2, respectively. Subjects with a total score > or = 5 were considered to have autonomic neuropathy. Forty subjects with CRF on hemodialysis were included in this study. None of the subjects had diabetes mellitus or any other etiology that could cause autonomic neuropathy. RESULTS: Thirty-five of 40 subjects (87.5%) had abnormal autonomic tests. In 35 subjects, the relationship between autonomic neuropathy and biochemical parameters, effects of treatment with vitamin D and erythropoietin, and urea reduction rate were studied. No relationship was found between autonomic neuropathy and age, time on hemodialysis, urea reduction rate, albumin, ferritin, calcium, inorganic phosphorus, intact parathyroid hormone, hemoglobin levels, and treatment with vitamin D and erythropoietin. The abnormal test results were as follows: 20 subjects (50%) in the heart rate response to the Valsalva Maneuver, 31 (77.5%) in the heart rate variation during deep breathing, 28 (70%) in the heart rate response to standing up, 6 (15%) in the blood pressure response to standing up, and 31 subjects (77.5%) in the blood pressure response to hand grip exercise tests. Among these five tests, the two most abnormal tests were the heart rate variation during deep breathing and the blood pressure response to hand grip exercise. CONCLUSION: Patients with CRF on hemodialysis frequently have autonomic neuropathy. For the diagnosis and follow-up of patients, five cardiovascular autonomic reflex tests are generally used. In this study, it was determined that performing only one test instead of all five tests has a high sensitivity and is more practicable in terms of determining autonomic neuropathy.