How much cerebrospinal fluid does the choroid plexus produce each day?

• A. 100 mils
• B. 250 mils
• C. 500 mils
• D. 1000 mils

Answer: (C)

The key idea is the rate at which cerebrospinal fluid is produced by the choroid plexus. In a healthy adult, CSF is produced at about 0.35 mL per minute, which comes to roughly 500 mL per day. This production rate, combined with normal absorption through the arachnoid granulations, keeps the CSF volume relatively constant and ensures stable intracranial pressure. Because of that, the figure around half a liter per day is the standard reference.

Options that propose much less or much more than this rate don’t align with how CSF turnover works in the brain. Producing only about 100 mL or 250 mL daily would be insufficient to sustain normal CSF volume and turnover, while producing around 1000 mL daily would overwhelm absorption and could raise intracranial pressure. Therefore, the best answer reflects the typical adult production of about 500 mils per day.