The influence of 25-hydroxyvitamin D and High-Density Lipoprotein Cholesterol on BIA Resistance results and aging on BIA Reactance results in elderly people.

BACKGROUND & AIMS: The use of Bioimpedance (BIA) as a bedside method of evaluation of body composition increased in the last years. However there are still some questions about correct interpretation of the raw data, reactance and resistance, as measures of body composition. This study investigated the relationship of age, physical activity practice, Body Mass Index (BMI), 25-hydroxyvitamin D and serum lipoproteins in BIA data of resistance and reactance.

METHODS: A transversal study was performed with elderly women who practiced regular physical activity (Group 1) and community dwelling elderly women (Group 2). Blood test, antrophometric measures and BIA exam were performed. As some studies had suggested, the ones with a BMI superior to 34 Kg/m2 were excluded. Students T-test was applied to assess differences between both groups, and due to its results, it was performed a stepwise multiple regression analysis.

RESULTS: The results of 320 elderly women with a BMI ≤34 Kg/m2 (Group 1 = 225; Group 2 = 95) were analyzed. At the blood test, there was a statistically significant difference for total-cholesterol, LDL-cholesterol, High-Density Lipoprotein Cholesterol and 25-hydroxyvitamin D. We observed an increase of 0.42 OHMS in BIA Resistance for each increment of 1 nmol/dL of 25-hydroxyvitamin D (p < 0.005), and an increase of 1 mg/dL of High-Density Lipoprotein Cholesterol led to an increase of 0.655 OHMS in BIA Resistance (p < 0.005). Also, it was observed that an increment of 1 year old have showed a reduction of 0.038 OHMS in BIA Reactance (p < 0.1).

CONCLUSIONS: BIA Reactance was influenced by aging and BIA Resistance was influenced by High-Density Lipoprotein Cholesterol and 25-hydroxyvitamin D.