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Fig. 3 | Journal of Neuroinflammation

Fig. 3

From: Spatial and temporal variation of routine parameters: pitfalls in the cerebrospinal fluid analysis in central nervous system infections

Fig. 3

Influence of blood contamination of the CSF on Reiber–Felgenhauer nomograms—hypothetical cases. Contamination of CSF by blood can falsify a finding of intrathecal immunoglobulin synthesis, as estimated by Reiber–Felgenhauer nomograms. To illustrate this fact, we performed the following model calculation. In samples without blood contamination (filled squares) we calculated with the following concentrations: albumin CSF 200 mg/l, serum 40,000 mg/l; IgG CSF 20 mg/l, serum 10,000 mg/l; IgA CSF 2 mg/l, serum 2000 mg/l; IgM CSF 1 mg/l, serum 2000 mg/l. A blood contamination of 0.1% (filled triangles) would raise the CSF concentrations to the following values, whereas the concentrations in blood would remain unchanged: albumin CSF 240 mg/l; IgG CSF 30 mg/l; IgA CSF 4 mg/l; IgM CSF 3 mg/l. A blood contamination of 1% (filled circles) would rise the CSF concentrations to the following values, whereas again the concentrations in blood would remain unchanged: albumin CSF 600 mg/l; IgG CSF 120 mg/l; IgA CSF 22 mg/l; IgM CSF 21 mg/l. Please note that blood contamination causes an increase in all quotients. The relative rise in the quotients increases with the size of the molecules studied. Even a low blood contamination can falsify an intrathecal synthesis of IgM. A blood contamination of 1% would seemingly lead to an intrathecal IgA and IgM synthesis. For these reasons, an intrathecal IgM synthesis in the presence of erythrocytes or hemoglobin in CSF must be interpreted with caution, and beyond a blood contamination 0.1% these nomograms should not be used

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