What is the normal CSF specific gravity range?

• A. 1.040-1.050
• B. 0.990-0.995
• C. 1.020-1.025
• D. 1.006-1.008

Answer: (D)

Understanding what CSF specific gravity tells you helps here: it’s a measure of how dense the cerebrospinal fluid is compared with water. CSF is mostly water with small amounts of protein, glucose, and minerals, so its density sits only a little above water. The normal range is about 1.006 to 1.008, meaning CSF is just a touch denser than water but still very close to it.

If the value were much higher, like around 1.04 to 1.05, that would suggest unusually concentrated CSF, which isn’t typical under normal conditions. Values closer to 0.990–0.995 would be lighter than water and aren’t characteristic of normal CSF either. A value around 1.020–1.025 is also outside the normal range. So the 1.006–1.008 range best fits normal CSF.