Glucose (CSF)

Test Details
TAT (TURNAROUND TIME) 10 - 14 days
CPT CODE 82947
PRICE $105
  • CSF Collection Tubes (set of 5 tubes per kit)

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Clinical Information
Clinical Significance

CSF glucose (NC10) can be used for the diagnosis of glucose transporter type 1 deficiency syndrome (Glut1-DS). To be useful for diagnosis of Glut1-DS, CSF glucose is measured at the same time in order to calculate the CSF/Plasma glucose ratio. For assessment of Glut1-DS, plasma glucose testing MET24 must be ordered. The single most important laboratory observation in Glut1-DS is hypoglycorrhachia (reduced cerebrospinal fluid (CSF) glucose concentration). Following a four-hour fast, a blood sample is obtained just before performing the lumbar puncture.

The blood glucose concentration should be normal, ruling out hypoglycemia as the cause of the hypoglycorrhachia. The CSF/blood glucose ratio usually is less than 0.4 (range 0.19 to 0.59) in persons with Glut1-DS; however, this value is less reliable than the absolute CSF glucose value. All affected individuals reported to date have had CSF glucose values below 60 mg/dL (range: 16.2 to 52 mg/dL); in more than 90% it is below 40 mg/dL and in approximately 10% it is 41-52 mg/dL. Additional Findings: CSF lactate (TEST: MET07) ( concentration is low-normal or low, often below 1.3 mmol/L or 11.7 mg/dl (range from 5.4 to 13.5 mg/dL)

Glucose transporter type 1 deficiency syndrome (Glut1-DS) usually presents in one of two ways: Classic Glut1 DS (~90% of affected individuals). Seizures (onset between ages 1 and 6 months in ~70%, before age 2 years in ~90%, and after age 2 years in ~10%); delayed neurologic development, dysarthria, acquired microcephaly and complex movement disorders including ataxia, dystonia and chorea. Non-epileptic Glut1 DS (~10% of affected individuals). No clinical seizures and a milder phenotype, often demonstrating paroxysmal dyskinesias including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1-DS) is now known to be a continuum that includes the classic phenotype as well as dystonia 9, dystonia 18, atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings such as intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures begin before age two years in approximately 90% and later in approximately 10%. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continuous with fluctuations in severity influenced by environmental factors such as fasting, fever, and intercurrent infection. Symptoms often improve substantially when a ketogenic diet is started.

Specimen Information
Acceptable Sample Types
  • Cerebrospinal Fluid (CSF)
Sample Preparation: Fill the tubes sequentially to the marked line Tube 1: 0.5 milliliter, Tube 2: 1.0 milliliter, Tube 3: 1.0 milliliter, Tube 4: 1.0 milliliter, Tube 5: 1.0 milliliter Without MNG CSF Collection Kit: Collect samples into 5 numbered 2.0 mL microcentrifuge tubes (or similar): Tube 1: 0.5 milliliter, Tube 2: 1.0 milliliter, Tube 3: 1.0 milliliter, Tube 4: 1.0 milliliter, Tube 5: 1.0 milliliter OR Collect entire sample into a single sterile tube, which is considered a pooled CSF sample. Neurotransmitter analysis may only be informative for certain disorders (NC04 analysis). Please contact the laboratory for more information.
Shipping Condition: Ship samples priority overnight on 3-4 lbs of dry ice. Sample must arrive in our lab Monday - Saturday. We do NOT accept Sunday or holiday deliveries.

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