掌握病患體液和營養狀態的變化對於許多疾病的治療及預後評估是很重要的。在各種人體組成分析方法中，生物阻抗分析具有簡便、快速、非侵入性及準確的優點。生物阻抗分析依功能可分為單頻及多頻率分析法，依檢查部位可分為全身性及區段性，並依校正公式而間接估算出身體組成比例。另外也可以生物阻抗向量分析法來追蹤身體組成的變化。隨著生物阻抗分析方法的精進，生物阻抗分析已廣泛地應用在營養學、運動醫學與內科學。本文回顧近年文獻關於生物阻抗分析之原理及應用於內科學的現況。

Understanding the dynamic change of fluid and nutrition status is very important for patient’s therapeutic plan and outcome assessment. Bioimpedance analysis has advantages of inexpensive, easy, noninvasive and
accuracy compared with other methods for body composition analysis. Bioimpedance analysis can be classified into single frequency and multi-frequency according to its function. It also can be classified into whole-body and segmental bioimpedance analysis according to its exam area. Bioimpedance analysis indirect estimates body composition from correlation equation. In addition, we also can utilize bioimpedance vector analysis to monitor the change of body composition. As progressive improves in bioimpedance analysis, it is widespread used in clinical nutrition, sports medicine and internal medicine. We introduce the basic principle of bioimpedance analysis and review studies about current applications in internal medicine.