51 - 55 Physiology SBAs for the Primary FRCA
Question 51
You have generously and deftly performed a lumbar puncture for the medical team, and the registrar decides to quiz you as you fiddle with the manometer.
Which of the following is true?
- There is more sodium in plasma than CSF
- There is more magnesium in plasma than CSF
- There is less glucose in plasma than CSF
- There is more bicarbonate in CSF than plasma
- There is more chloride in CSF than plasma
Answer
- There is more chloride in CSF than Plasm
CSF is essentially the same as plasma when looking at the positive ions - the numbers vary depending on where you're reading - however there's more significant difference when you look at the negative ions.
- There is very little protein in normal CSF
- To compensate for this, there are more chloride ions to maintain electroneutrality
Read more about CSF and head stuff here.