Immunoglobulin G Synthesis Rate, Cerebrospinal Fluid

CPT: 82040; 82042; 82784(x2)
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Test Details


  • Central Nervous System IgG Synthesis
  • Cerebrospinal Fluid IgG Synthesis
  • CNS IgG Synthesis
  • CSF IgG Synthesis
  • IgG Synthesis Rate
  • IgG, Spinal Fluid:Serum Ratio
  • Spinal Fluid IgG Synthesis

Test Includes

IgG and albumin quantitation in both serum and spinal fluid samples and the calculation of IgG synthesis rate in the central nervous system


Evaluate the de novo rate of synthesis of IgG in CNS; diagnose inflammatory and autoimmune diseases involving CNS, in particular, multiple sclerosis; determine if IgG synthesis rate is based on the quotient of average normal serum IgG/average normal CSF IgG


CSF IgG, CSF albumin, and serum IgG: immunologic; serum albumin: spectrophotometry; synthesis rate by calculation

Reference Interval

Synthesis rate: -9.9 to +3.3 mg/24 hours

Additional Information

Tourtellotte IgG synthesis rate is theoretically the most definitive approach to determining IgG production by the central nervous system. It is based upon an empirically-derived formula, the validity of which, however, has been verified by radiolabeled IgG experiments.1 The synthesis rate formula involves a constant described as “a ratio constant that quantitatively determines the proportion of CSF IgG that normally passes by filtration from the serum into the CSF across an intact BBB” (blood brain barrier). The formula is given as:

de novo CNS IgGsyn = ((IgGcsf - IgGs/369) - (Albcsf - Albs/230) (IgGs / Albs) (0.43)) x 5

A study by Tourtellotte and associates has shown that about 90% of multiple sclerosis patients show evidence of enhanced IgG synthesis.2 A study from the Cleveland Clinic indicates a sensitivity and specificity comparable to that for the IgG index in predictive value for MS.3 Sensitivity (96%) and specificity (98%) applied to a group considered as definite multiple sclerosis. A group of “possible multiple sclerosis” patients included a number of cases in which CNS IgG synthesis was normal − just 55% had an elevated rate. In the group with “neurologic diseases other than MS,” 96% of patients had normal CNS IgG synthesis. The study suggests that determination of CSF IgG synthesis rate contributes importantly to the diagnosis of MS. The study also emphasizes that correlations between test results and diagnoses are dependent upon the validity of what must remain a clinical neurologic diagnosis.

Specimen Requirements


Serum and cerebrospinal fluid (CSF)


1.5 mL serum and 1 mL CSF

Minimum Volume

0.7 mL serum and 0.5 mL CSF


Red-top tube or gel-barrier tube and sterile (CSF) container

Storage Instructions

Room temperature

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x2

Causes for Rejection

Blood in CSF; failure to obtain blood and CSF specimens

Clinical Information


1. Tourtellotte WW, Potvin AR, Fleming JO, et al. Multiple sclerosis: Measurement and validation of central nervous system IgG synthesis rate. Neurology. 1980; 30(3):240-244. 7189023
2. Tourtellotte WW, Staugaitis SM, Walsh MJ, et al. The basis of intra-blood-brain-barrier IgG synthesis. Ann Neurol. 1985; 17(1):21-27. 3985581
3. Valenzuela R, Mandler R, Goren H. Immunonephelometric quantitation of central nervous system IgG daily synthesis in multiple sclerosis. Clinical evaluation using predictive value theory. Am J Clin Pathol. 1982; 78(1):22-28.7102604


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
085928 Immunoglobulin G,Syn Rate,CSF 001081 Albumin, Serum g/dL 1751-7
085928 Immunoglobulin G,Syn Rate,CSF 001776 Immunoglobulin G, Qn, Serum mg/dL 2465-3
085928 Immunoglobulin G,Syn Rate,CSF 012212 IgG, Quant, CSF mg/dL 2464-6
085928 Immunoglobulin G,Syn Rate,CSF 012230 Albumin, CSF mg/dL 1746-7
085928 Immunoglobulin G,Syn Rate,CSF 085937 IgG, Syn Rate,CSF mg/day 14116-8

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