What is a normal CSF result?

In adults, normal CSF has fewer than 5 white cells per microlitre, all mononuclear, a protein of 0.15 to 0.45 g/L, and a CSF to serum glucose ratio above 0.6. Values outside these ranges suggest an inflammatory or infectious process.

How does the tool tell bacterial from viral meningitis?

Bacterial meningitis typically shows a high neutrophil-predominant cell count, high protein, and a low glucose ratio below 0.4. Viral meningitis shows a lower lymphocyte-predominant count with normal glucose and only mildly raised protein. The tool matches your values to these signatures.

Why is the CSF:serum glucose ratio more useful than CSF glucose alone?

CSF glucose tracks blood glucose, so a low CSF glucose in a hyperglycaemic patient may still be normal. The ratio corrects for serum glucose and is a more reliable marker of consumption by bacteria, TB, or fungi, where it falls below 0.5.

What pattern suggests tuberculous or fungal meningitis?

A lymphocyte-predominant pleocytosis combined with a low glucose ratio and a high — sometimes very high — protein points to TB or fungal meningitis. These warrant AFB stain and culture, TB-PCR, cryptococcal antigen, and India ink testing.

Can I rely on the CSF pattern alone to decide treatment?

No. Patterns overlap, and early or partially treated bacterial meningitis can mimic a viral picture. Never withhold empirical antibiotics on CSF figures alone; always combine them with the clinical picture, Gram stain, culture, and PCR.

CSF Analysis Interpreter

Cerebrospinal fluid analysis is the central test in suspected meningitis. The combination of cell count, cell type, protein, and the glucose ratio produces recognisable patterns that point toward a bacterial, viral, tuberculous, or fungal cause. This tool maps your values onto those patterns.

How it works

The interpreter computes the CSF:serum glucose ratio and then matches the overall picture against classic signatures:

Bacterial  WBC >500, neutrophil-predominant, protein >1 g/L, ratio <0.4
Viral      WBC 10–500, lymphocyte-predominant, normal glucose, mild protein
TB/Fungal  lymphocyte-predominant, ratio <0.5, protein high to very high
Normal     WBC <5, protein <0.45 g/L, ratio >0.6

The glucose ratio is calculated as CSF glucose ÷ serum glucose, which corrects for the patient’s blood sugar and is far more reliable than CSF glucose read in isolation.

Notes and cautions

These patterns are typical, not absolute. Early bacterial meningitis can present with a near-normal or lymphocytic picture, and prior antibiotics blunt the classic findings of a partially treated infection. The tool is a structured aid to the differential — it does not replace Gram stain, culture, PCR, and clinical judgement, and empirical therapy should never be delayed while awaiting these results.