Carbon dioxide binding capacity of 20.2 mmol/L is abnormal and slightly low. Normally, carbon dioxide binding capacity is 23 to 31 mmol/L, with an average value of 27 mmol/L. A carbon dioxide binding capacity of 20.2 mmol/L is mildly low and is commonly associated with metabolic acidosis and respiratory alkalosis. Metabolic acidosis, generally associated with excessive acid production, occurs, for example, when diabetics cause ketoacidosis or cause starvation ketosis. Respiratory alkalosis, on the other hand, suggests alveolar hyperventilation. Carbon dioxide binding capacity of 20.2mmol/L is not particularly low, it is recommended to observe for a period of time, if it continues to fall, or if discomfort occurs, it needs to be taken seriously, please seek the guidance of a doctor in a timely manner, to clarify the cause of the problem, and then carry out targeted treatment.