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Lower values for immunoglobulin M in cerebrospinal fluid when sampled with an atraumatic Sprotte needle compared with
S Ohman1, J Ernerudh, P Forsberg
1Department of Clinical Chemistry, University Hospital of Linköping, Sweden.
Abstract:
Immunoglobulin M (IgM) has a very low concentration in cerebrospinal fluid (CSF) compared with serum, and therefore determinations of IgM in CSF are highly sensitive to pre-analytical errors caused by contamination with serum or interstitial fluid. Capillary attraction causes a thin layer of liquid containing serum proteins to be formed inside a conventional (Quincke) needle during penetration of tissue. To investigate this source of pre-analytical error, 35 patients had lumbar punctures using a 22 G atraumatic (Sprotte) or 25 G conventional (Quincke) needle according to a randomized scheme, and the IgM concentrations in CSF and serum were determined. The CSF IgM concentrations for samples taken with a Sprotte needle were significantly lower than those taken with a Quincke needle (P < 0.05), whereas the corresponding serum IgM concentrations and CSF erythrocyte counts did not differ significantly. The difference indicates that CSF IgM concentrations determined after conventional sampling may be falsely increased by contamination. We conclude that IgM concentrations in CSF samples taken with the atraumatic technique are more accurate, and recommend the use of this technique when CSF IgM is to be determined.
Insights
Cerebrospinal fluid (CSF) immunoglobulin M (IgM) levels are falsely elevated with conventional needles due to serum contamination. Using atraumatic needles provides more accurate IgM measurements in CSF.
Area of Science:
- Neurology
- Clinical Chemistry
- Laboratory Medicine
Background:
- Immunoglobulin M (IgM) concentrations are significantly lower in cerebrospinal fluid (CSF) than in serum.
- Accurate determination of CSF IgM is crucial for diagnosing neurological conditions.
- Pre-analytical errors, particularly serum contamination, can compromise CSF IgM measurements.
Purpose of the Study:
- To investigate the impact of needle type on pre-analytical errors in CSF IgM determination.
- To compare CSF IgM concentrations obtained using atraumatic (Sprotte) versus conventional (Quincke) needles.
- To identify the optimal needle technique for accurate CSF IgM analysis.
Main Methods:
- A randomized study involving 35 patients undergoing lumbar puncture.
- Comparison of CSF and serum IgM concentrations using 22 G atraumatic (Sprotte) and 25 G conventional (Quincke) needles.
- Analysis of CSF erythrocyte counts to assess for blood contamination.
Main Results:
- CSF IgM concentrations were significantly lower when using the atraumatic Sprotte needle compared to the conventional Quincke needle (P < 0.05).
- No significant differences were observed in serum IgM concentrations or CSF erythrocyte counts between the two needle types.
- The findings suggest serum contamination is a significant factor in elevated CSF IgM levels with conventional needles.
Conclusions:
- Conventional lumbar puncture needles can introduce serum contamination, leading to falsely elevated CSF IgM levels.
- Atraumatic needles (Sprotte) yield more accurate CSF IgM measurements by minimizing pre-analytical errors.
- The use of atraumatic needles is recommended for reliable CSF IgM determination.