CSF glucose or glycorrhachia is a measurement used to determine the concentration of

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

(CSF).

Normal values in humans

The glucose level in CSF is proportional to the

blood glucose level Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the blo ...

and corresponds to 60-70% of the concentration in blood. Therefore, normal CSF glucose levels lie between 2.5 and 4.4 mmol/L (45–80 mg/dL).

Abnormalities in CSF glucose concentration

Low CSF glucose levels

Hypoglycorrhachia (low CSF glucose levels) can be caused by CNS infections, inflammatory conditions,

subarachnoid hemorrhage Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consci ...

hypoglycemia Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose belo ...

(low blood sugar), impaired glucose transport (e.g. GLUT1 deficiency syndrome), increased CNS glycolytic activity and

metastatic carcinoma Metastatic carcinoma is cancer that is able to grow at sites distant from the primary site of origin; thus, dissemination to the skin may occur with any malignant neoplasm, and these infiltrates may result from direct invasion of the skin from under ...

. CSF glucose levels can be useful in distinguishing among causes of

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

as more than 50% of patients with

bacterial meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

have decreased CSF glucose levels while patients with

viral meningitis Viral meningitis, also known as aseptic meningitis, is a type of meningitis due to a viral infection. It results in inflammation of the meninges (the membranes covering the brain and spinal cord). Symptoms commonly include headache, fever, photop ...

usually have normal CSF glucose levels. Decrease in glucose levels during a CNS infection is caused due to glycolysis by both white cells and the pathogen, and impaired CSF glucose transport through the blood-brain barrier.

High CSF glucose levels

There is no pathologic process that directly leads to hyperglycorrhachia (high CSF glucose levels) and therefore, high CSF glucose levels have no specific diagnostic importance. However, elevated

blood sugar Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the blo ...

levels (

hyperglycemia Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/L (200 mg/dL), but symptoms may not start to become noticeable until even ...

) result in elevated CSF glucose levels as the CSF glucose level is proportional to the blood glucose level with glucose being actively transported as well as simply diffusing down the concentration gradient from blood to CSF. In addition, damage to small blood vessels during lumbar puncture (traumatic tap) can lead to an increased CSF glucose since the blood that enters the collected CSF sample contains higher levels of glucose. CSF glucose levels do not generally exceed 16.7 mmol/L (300 mg/dL).

References

{{CSF tests Body fluids CSF tests

Normal values in humans

Abnormalities in CSF glucose concentration

Low CSF glucose levels

High CSF glucose levels

See also

References