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In physiology, base excess and base deficit refer to an excess or deficit, respectively, in the amount of base present in the blood. The value is usually reported as a concentration in units of mEq/L, with positive numbers indicating an excess of base and negative a deficit. A typical reference range for base excess is −2 to +2 mEq/L. Comparison of the base excess with the reference range assists in determining whether an acid/base disturbance is caused by a respiratory, metabolic, or mixed metabolic/respiratory problem. While carbon dioxide defines the respiratory component of acid-base balance, base excess defines the metabolic component. Accordingly, measurement of base excess is defined under a standardized pressure of carbon dioxide, by titrating back to a standardized blood pH of 7.40. The predominant base contributing to base excess is bicarbonate. Thus, a deviation of serum bicarbonate from the reference range is ordinarily mirrored by a deviation in base excess. However, base excess is a more comprehensive measurement, encompassing all metabolic contributions. ==Definition== Base excess is defined as the amount of strong acid that must be added to each liter of fully oxygenated blood to return the pH to 7.40 at a temperature of 37°C and a pCO2 of . A base deficit (i.e., a negative base excess) can be correspondingly defined in terms of the amount of strong base that must be added. A further distinction can be made between actual and standard base excess: actual base excess is that present in the blood, while standard base excess is the value when the hemoglobin is at 5 g/dl. The latter gives a better view of the base excess of the entire extracellular fluid.〔(Acid-Base Tutorial — Terminology )〕 The term and concept of base excess were first introduced by Poul Astrup and Ole Siggaard-Andersen in 1958. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「base excess」の詳細全文を読む スポンサード リンク
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