Borrelia cerebrospinal fluid
diagnosis
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Borrelia cerebrospinal fluid
diagnosis
A dangerous bacteria called Borrelia causes serious infections
in man. In late stages of this disease, the human brain is attacked by these
bacteria.
Therefore, diagnosis of Borrelia infections in the brain is very important, but
involves several complicated calculations of the measurement results of Borrelia
diagnostics.
Below, you can see these calculations.
Application version: May 2000
|
Cerebrospinal Fluid Diagnosis To be used with |
1. IntroductionThe diagnosis of neuroborreliosis relies on the detection of inthratecally
produced Borrelia-specific IgG and IgM antibodies. IgG and IgM concentrations
are estimated in BBU/ml (Biomedica Borrelia Units/ml) by quantitative
measurements using IgG and IgM ELISAs.
The ratios between specific Borrelia antibody-concentrations and total
immunoglobulin-concentrations are estimated for both serum and cerebrospinal
fluid (CSF). These so-called antibody-indexes are used to distinguish between
inthratecally produced Borrelia-antibodies, and those who entered the
cerebrospinal fluid space passively by passing the blood-brain barrier.
The limit Qlim is calculated using the quotient diagram according to Reiber(1,2), which guarantees that no false-negative antibody-indexes are calculated for a polyspecific inthratecally immune response.
Borrelia-antibodies are estimated quantitatively in serum and cerebrospinal fluid. Only in case of positive cerebrospinal fluid results ³ 5 BBU/ml), total-IgG and/or total-IgM and albumin in serum and cerebrospinal fluid have to be determined in order to calculate the Borrelia-specific antibody-indexes. The following protocol describes the necessary calculations.
2. Literature
3. Sample dilutionThe assay is performed according to the Biomedica Borrelia IgG and IgM ELISA package inserts.
|
Sample dilution |
|
| IgG - serum IgG - cerebrospinal fluid |
1 : 101 1 : 3 |
| IgM - serum IgM - cerebrospinal fluid |
1 : 101 1 : 2 |
Samples with results >30 BBU/ml should be repeated by using higher dilution rates. We suggest dilution rates as described in chapter 7.
4. Calculation & interpretation of the results using MS EXCELIn the following chapters 5-10, it is shown how to evaluate, assess, and
interpret the measurement results obtained in chapter 3
according to the Reiber quotient diagram(1,2).
However, these calculations aren't very handy. To simplify the calculation and
documentation of the measurement results, an easy-to-use utility was developed,
which is basically a MS EXCEL 97 file with a macro in it.
Please click here to download a ZIP-file containing the Excel macro together with instructions for use in PDF-format (size: 287 kB).
5. Test evaluationTo evaluate the results, the BBU/ml for sera and cerebrospinal fluides for both IgG and IgM are calculated, as described in the package inserts for IgG and IgM.
The same formula applies to both IgG und IgM:
|
|
|
Result |
Evaluation |
|
| Serum | > 11 BBU/ml 9 - 11 BBU/ml < 9 BBU/ml |
positive |
| Cerebrospinal fluid | ³ 5
BBU/ml < 5 BBU/ml |
positive |
6. Assessment of the resultsThe results from chapter 5 are assessed as follows:
|
Result |
Assessment and further procedure |
| Serum £ 11 BBU/ml CSF < 5 BBU/ml |
This is a negative result for Borrelia
IgG-antibodies in serum and cerebrospinal fluid, which means: • no indication for a neuroborreliosis, therefore • estimation of the antibody-index AIIgG not necessary. |
| Serum > 11 BBU/ml CSF < 5 BBU/ml |
This is a positive result for Borrelia
IgG-antibodies in serum, and a negative result for Borrelia IgG-antibodies
in cerebrospinal fluid, which means: • evidence for an acute or past Borrelia-infection, therefore • no indication for a neuroborreliosis, estimation of the antibody-index AIIgG not necessary. |
| Serum £ 11 BBU/ml CSF ³ 5 BBU/ml |
This is a negative result for Borrelia
IgG-antibodies in serum, and a positive result for Borrelia IgG-antibodies
in cerebrospinal fluid, which means: • possibility for neuroborreliosis, therefore • estimation of the antibody-index AIIgG is necessary. |
| Serum > 11 BBU/ml CSF ³ 5 BBU/ml |
This is a positive result for Borrelia
IgG-antibodies in serum, and a positive result for Borrelia IgG-antibodies
in cerebrospinal fluid, which means: • possibility for neuroborreliosis, therefore • estimation of the antibody-index AIIgG is necessary. |
If the result in cerebrospinal fluid is negative, estimation of the
Borrelia-specific antibody-index isn't necessary and the protocol should be
stopped here.
If either IgG- or IgM-results in cerebrospinal fluid are positive, the protocol
should be proceed.
Subsequently, the procedures for IgG- and IgM-calculations are identical.
The Borrelia-specific antibody-index is only calculated upon a positive result for cerebrospinal fluid.
7. Calculation of the Borrelia-specific antibody-concentrations in serum and
cerebrospinal fluidThe Biomedica Borrelia ELISA results are linear up to 30 BBU/ml.
Serum- and/or cerebrospinal fluid-results above 30 BBU/ml should be re-assayed
using higher dilution rates.
Suggestion:
|
original dilutions |
further dilutions | |
| Serum IgG and IgM | 1:101 | 1:1010 ® 1:5050 |
| Cerebrospinal fluid IgG Cerebrospinal fluid IgM |
1:3 1:2 |
1:5 ®
1:10 1:5 ® 1:10 |
The concentration BBU/ml in the undiluted samples is calculated as follows:
|
Concentration BBU/ml in the undiluted sample = BBU/ml x dilution |
Example serum IgG: |
measured BBU/ml: 4.4 dilution rate: 1:1010 4.4 x 1010 = 4444 BBU/ml in the undiluted serum |
| Example cerebrospinal fluid IgG: | measured BBU/ml: 8 dilution rate: 1:3 8 x 3 = 24 BBU/ml in the undiluted cerebrospinal fluid |
The Borrelia-specific IgG- and IgM-quotients Qspez(IgG) resp. Qspez(IgM) are calculated according to the following formulas:
|
|
Example IgG: 
8. Calculation of QIgG, QIgM, QAlb, Qlim(IgG),
Qlim(IgM)Total-IgG, total-IgM and albumin-concentrations have to be determined in
serum and cerebrospinal fluid.
These protein concentrations are then used to calculate the quotients for IgG,
IgM and albumin as follows:
|
|
Example IgG: |
conc. cerebrospinal fluid = 8.6 mg/l conc. serum = 9500 mg/l  |
| Example albumin: | conc. cerebrospinal fluid = 62.7 mg/l conc. serum = 49000 mg/l  |
The limits Qlim(IgG) and Qlim(IgM) are calculated using QAlb, according to the following formulas:
|
Qlim(IgG) = |
Example IgG: |
QAlb = 0.00128 Qlim(IgG) = 
==  == 0.00087 |
9. Calculation of the specific antibody-indexes AIIgG and AIIgMThe estimated values for QIgG and Qlim(IgG) as well as QIgM and Qlim(IgM) are compared to each other. AIIgG and AIIgM are calculated as follows:
if QIgG < Qlim(IgG): 
|
if QIgM < Qlim(IgM): 
|
if QIgG > Qlim(IgG): 
|
if QIgM > Qlim(IgM): 
|
10. Interpretation of the antibody-indexes|
AIIgG resp. AIIgM £ 1.3 = normal AIIgG resp. AIIgM > 1.3 and < 1.5 = borderline AIIgG resp. AIIgM ³ 1.5 = pathologic |
Normal: |
AI-values £ 1.3 Anti-Borrelia-antibodies detected in cerebrospinal fluid moved passively from the serum through the blood-brain barrier into the cerebrospinal fluid space. Þ No indication for neuroborreliosis. |
| Borderline: | AI-values > 1.3 and < 1.5 No clear evidence for an intrathecally production of anti-Borrelia antibodies. Þ Repetition of the assay recommended, or new collection of serum and cerebrospinal fluid, and repetition of the assay. |
| Pathologic: | AI-values ³ 1.5 Strong evidence for an intrathecal production of anti-Borrelia antibodies. Þ Possibility for neuroborreliosis. |
11. Clinical evaluation data|
Code No |
Clinical Diagnosis |
Anamnesis |
Therapy |
BBU CSF IgG | BBU serum IgG |
Q Alb |
Q spez IgG 1:50 |
Q IgG |
Q lim IgG |
AI IgG |
CSF diagnosis |
||
|
1:3 |
1:50 |
1:101 |
1:5050 |
||||||||||
|
A1 |
Radikulopathy C6 |
Status post
neuroborreliosis |
unknown |
6.0 |
7.9 |
0.00646 |
0.00752 |
0.00304 |
0.00473 |
2.47025 |
borr. positive borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. positive |
||
|
B1 |
healthy control |
1.1 0.2 0.3 0.1 0.1 0.1 1.8 0.4 0.1 |
21.2 1.0 3.2 1.5 1.4 0.8 13.3 2.7 1.9 |
0.00791 0.00391 0.01020 0.00330 0.00664 0.00400 0.00861 0.00735 0.00378 |
-- |
-- |
-- |
-- |
borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative |
||||
| Code No |
Clinical Diagnosis |
Anamnesis |
Therapy |
BBU CSF IgM |
BBU Serum IgM |
Q Alb |
Q spez IgM |
Q IgM |
Q lim IgM |
AI IgM |
CSF diagnosis |
|
1:2 |
1:101 |
||||||||||
|
A1 |
Radikulopathy C6 |
Status post
neuroborreliosis |
unknown |
0.2 |
10.3 |
0.00646 |
-- |
-- |
-- |
-- |
borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. positive borr. positive borr. negative borr. negative borr. negative borr. negative |
|
B1 |
healthy control |
0.1 |
12.2 |
0.00791 |
-- |
-- |
-- |
-- |
borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative borr. negative |
||
Last modified: 11. Jun 05
