[Bakerman]

Hello to everyone,

I had the neurologist suspect enough to run an Acetylchol Recep Bind Ab W/Rfx test. The results came back as follows:

F AChR Binding Abs, Serum <0.03 0.00-0.24 (nmol/L)
- Negative: 0.00 - 0.24
- Borderline: 0.25 - 0.40
- Positive: > 0.40
F AChR Modulating Ab >64 A 0-20 (%)
- Negative: <21
- Equivocal: 21 - 25
- Positive: >25
- The assay is linear between values of 12 and 64.
- Those <12 and >64 are reported as such. No single
- value for ACR-modulating antibody should be used as
- a sole basis for diagnosis or response to therapy.

The Doc. calls and tells me the test was positive and wanted me to redo it. This test is slightly differt which simply seems to be checking the blocking in addition to the binding & Modulating The results are as follows:

F AChR Binding Abs, Serum <0.03 0.00-0.24 (nmol/L)
- Negative: 0.00 - 0.24
- Borderline: 0.25 - 0.40
- Positive: > 0.40
F AChR Blocking Abs, Serum 16 0-25 (%)
- Negative: 0 - 25
- Borderline: 26 - 30
- Positive: >30
- .
- Results for this test are for research purposes
- only by the assay's manufacturer. The performance
- characteristics of this product have not been
- established. Results should not be used as a
- diagnostic procedure without confirmation of the
- diagnosis by another medically established
- diagnostic product or procedure.
F AChR Modulating Ab <12 0-20 (%)
- Negative: <21
- Equivocal: 21 - 25
- Positive: >25
- The assay is linear between values of 12 and 64.
- Those <12 and >64 are reported as such. No single
- value for ACR-modulating antibody should be used as
- a sole basis for diagnosis or response to therapy

So there was a broad swing in the modulating AB. Is this normal to see?
I have my good and bad days and was wondering if they caught me on a good day the second time around. I am very symptomatic for MG and was glad to finally get a name to go with my condition and was more thrilled to find there is treatment for it.

I read that false positives are rare but how rare are false negatives. Do I have MG or not? My DR. has not requested a follow up visit. Any help deciphering these test?

I found this chart and read it that positive Modulating antibodies only is a "Confirmation of diagnosis".


Test Selection Guide
Applications AChR Antibody Striational Antibody Titin Antibody
MuSK
Antibody
Binding Blocking Modulating
Initial screening x x x
Confirmation of diagnosis x xa x x xa
Monitoring therapeutic response and disease progression x x x x
Thymoma diagnosis x x
This table is provided for informational purposes only and is not intended as medical advice. A physician's test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

AChR, acetylcholine receptor.

a When binding antibody is negative

Back to my question, can the test flucuate that much in a months time?