Background: Lipedema and Dercum's disease (DD) are incompletely characterized adipose tissue diseases, and objective measures of disease profiles are needed to aid in differential diagnosis. We hypothesized that fluid properties, quantified as tissue water bioimpedance in the upper and lower extremities, differ regionally between these conditions. Methods and Results: Women (cumulative n = 156) with lipedema (n = 110), DD (n = 25), or without an adipose disease matched for age and body mass index to early stage lipedema patients (i.e., controls n = 21) were enrolled. Bioimpedance spectroscopy (BIS) was applied to measure impedance values in the arms and legs, indicative of extracellular water levels. Impedance values were recorded for each limb, as well as the leg-to-arm impedance ratio. Regression models were applied to evaluate hypothesized relationships between impedance and clinical indicators of disease (significance criteria: two-sided p < 0.05). Higher extracellular water was indicated (i) in the legs of patients with higher compared with lower stages of lipedema (p = 0.03), (ii) in the leg-to-arm impedance ratio in patients with lipedema compared with patients with DD (p ≤ 0.001), and (iii) in the leg-to-arm impedance ratio in patients with stage 1 lipedema compared with controls (p ≤ 0.01). Conclusion: BIS is a noninvasive portable modality to assess tissue water, and this device is available in both specialized and nonspecialized centers. These findings support that regional bioimpedance measures may help to distinguish lipedema from DD, as well as to identify early stages of lipedema.
Keywords: Dercum's disease; adiposis dolorosa; bioimpedance spectroscopy; lipedema; lipoedema.