Metabolic acidosis is a chronic condition that many people in the Western world have but do not realise it.1–3 It occurs when there is retention of acid in the body, which leads to a depletion in the bicarbonate stores of the body. The term metabolic acidosis is typically used when referring to low blood pH or acidemia due to a metabolic abnormality. However, this is inappropriate as most cases of metabolic acidosis do not have acidemia. In fact, a low blood pH is typically one of the last surrogate markers to become abnormal in those with low-grade metabolic acidosis.2 This is because the body maintains a normal blood pH at the expense of bicarbonate reserves. Metabolic acidosis primarily occurs inside the cell and in the fluid that surrounds our tissues (interstitial fluid).4 When checking for metabolic acidosis the clinician should look at fasting serum bicarbonate, urinary pH (with a measurement at least 4 hours separated from the last ingested meal) and 24-hour urinary citrate levels. While there is not a universally accepted way to diagnose low-grade metabolic acidosis, this paper will help to give the clinician insights into checking for this condition in their patients. Acidemia, or too much acid in the blood, only occurs when the body’s buffering capacity can no longer maintain a normal pH level. A normal blood pH is considered to be 7.35–7.45. However, even at a normal blood pH metabolic acidosis can occur. In fact, once the blood pH falls below 7.4, there is usually acid retention in the body and low-grade metabolic acidosis.2 However, the blood pH does not drop below the normal range until metabolic acidosis has become severe. Once this occurs it is usually referred to as ‘metabolic acidosis’ by the clinician. However, this is actually acidemia (or too …

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低度代谢性酸中毒是慢性病的驱动因素：21 世纪的公共卫生危机

代谢性酸中毒是西方世界许多人患有但没有意识到的慢性病。1-3 它发生在体内酸滞留时，导致体内碳酸氢盐储备耗尽。当指代由于代谢异常引起的低血液 pH 值或酸血症时，通常使用术语代谢性酸中毒。然而，这是不合适的，因为大多数代谢性酸中毒病例没有酸血症。事实上，低血液 pH 值通常是低度代谢性酸中毒患者最后出现异常的替代指标之一。2 这是因为身体以牺牲碳酸氢盐储备为代价维持正常的血液 pH 值。代谢性酸中毒主要发生在细胞内部和组织周围的液体（间质液）中。4 在检查代谢性酸中毒时，临床医生应查看空腹血清碳酸氢盐、尿液 pH 值（与最后一次摄入的膳食相隔至少 4 小时测量）和 24 小时尿柠檬酸盐水平。虽然没有普遍接受的方法来诊断低度代谢性酸中毒，但本文将有助于临床医生深入了解检查患者的这种情况。只有当身体的缓冲能力不再能维持正常的 pH 值时，才会发生酸血症或血液中酸过多。正常的血液 pH 值被认为是 7.35–7.45。然而，即使血液 pH 值正常，也可能发生代谢性酸中毒。事实上，一旦血液 pH 值降至 7.4 以下，体内通常会出现酸滞留和低度代谢性酸中毒。2 然而，在代谢性酸中毒变得严重之前，血液的 pH 值不会低于正常范围。一旦发生这种情况，临床医生通常将其称为“代谢性酸中毒”。然而，这实际上是酸血症（或太……