The decrease in sugar and chloride in septic and tuberculous meningitis is due to increased glucose anaerobic fermentation and consumption, increased cerebrospinal fluid protein content, and chloride loss. 1. Increased anaerobic fermentation and consumption of glucose: in purulent and tuberculous meningitis, the pathogen increases the body’s consumption of glucose, so the sugar content of body fluids decreases, the glucose that enters the cerebrospinal fluid decreases, and the amount of sugar in the cerebrospinal fluid decreases. In addition, the cells are destroyed to release glucose-degrading enzymes, resulting in the breakdown of glucose in the cerebrospinal fluid, which may also cause a decrease in the content. 2. Increase in protein content of cerebrospinal fluid: Chloride in cerebrospinal fluid mainly maintains osmotic pressure, when inflammation occurs in the meninges, such as purulent or tuberculous meningitis, the inflammatory exudate contains a large amount of albumin into the cerebrospinal fluid, and colloid osmolality is obviously increased, so chloride decreases in order to maintain the balance of osmolality of the cerebrospinal fluid. 3. Loss of chloride: frequent vomiting may occur when the meninges of patients with meningitis are irritated, leading to loss of chlorine in the body and a decrease in the chloride content of the cerebrospinal fluid. In severe cases, it is recommended to actively seek medical advice and follow the doctor’s instructions.