Symptoms are non specific.Symptoms may include chest pain, palpitations, headache, altered mental status such as severe anxiety due to hypoxia, decreased visual acuity, nausea, vomiting, abdominal pain, altered appetite and weight loss,muscle weakness and bone pains. Those in metabolic acidosis may exhibit deep, rapid breathing called Kussmaul respirations which is classically associated with diabetic ketoacidosis. Rapid deep breaths increase the amount of carbon dioxide exhaled, thus lowering the serum carbon dioxide levels, resulting in some degree of compensation. Over compensation via respiratory alkalosis to form an alkalemia does not occur.
Metabolic acidosis occurs when the body produces too much acid, or when the kidneys are not removing enough acid from the body. There are several types of metabolic acidosis. The main causes are best grouped by their influence on the anion gap.
Anion gap = ( [Na+] ) - ( [Cl-]+[HCO3-] )
As sodium is the main extracellular cation, and chloride and bicarbonate are the main anions, the result should reflect the remaining anions. Normally, this concentration is about 8-16 mmol/l (12±4). An elevated anion gap (i.e. more than 16 mmol/l) can indicate particular types of metabolic acidosis, particularly certain poisons, lactate acidosis and ketoacidosis.
Arterial blood gas sampling is essential for the diagnosis. The pH is low (under 7.35) and the bicarbonate levels are decreased.Due to respiratory compensation (hyperventilation), carbon dioxide is decreased and conversely oxygen is increased. An ECG can be useful to anticipate cardiac complications.