A low bicarbonate generally indicates a decrease in alkaline substances and an increase in acid in the blood. There are two general ways to measure this, one is with venous blood, where bicarbonate can be found in kidney work. There is also the method of blood gas analysis, where low bicarbonate is found in arterial blood. The indicators obtained by the two methods are close to each other and generally indicate metabolic acidosis or respiratory alkalosis. The causes of metabolic acidosis are generally renal insufficiency, diabetic ketoacidosis, and lactic acidosis. A common cause of respiratory alkalosis is hyperventilation, where the patient may experience deep, large breaths that cause excessive carbon dioxide excretion and lower bicarbonate.