How do I convert from U/ML into nmol/L?

bluedeep said:

Hi all - I am new to the forum (and diabetes too) and am in the process of being diagnosed if I am Type 1 LADA. I have done my GAD65Ab test a few weeks ago and just got the results in electronically. But will have an appointment with my doctor in about two weeks. So, naturally, I am trying to read and interpret the result myself but find this very difficult and frustrating because the measuring units in the articles I read on the web do not match the measuring units I see in the report. I should probably mention that I am located in Canada and the report maybe using some nomenclature used in Canada and US.

My report prints my result in measuring units U/ML. And it says that the reference range is <= 1.0 U/ML. My result is quite higher, but I can't gauge exactly what this means if I compare it with the information I read online where the measuring units are nmol/L. And the reference range is <= 0.02 nmol/L. I am guessing my results point to Type 1 LADA but am not completely sure...

How do I convert from U/ML into nmol/L?

Really appreciate the help!

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bluedeep said:

Thank you, @phoenix. This was very informative.

The problem for me now is that I am actually far more worried than before I knew/read this. My number is definitely placing me as Type 1 LADA, but there is potentially more than this: if I am reading all correctly, then I am 27 times (!) above the threshold. And so LADA can be just one of my - potentially longer - list of problems...

From this article here <http://thetinman.org/endocrine.html> I learnt that different Labs develop their own reference ranges and that there are three main ways to measure GAD65 (this below is a quote):

There are three ways to measure GAD65 antibodies: radio-immune assay (RIA), radiobinding assay (RBA) and enzyme-linked immunosorbent assay (ELISA). Labs develop their own reference ranges and results may vary by location:

(1) RIA levels of GAD65: [Source: Mayo Clinic]
-> For type 1 diabetes (and to differentiate from type 2 diabetes), thyroiditis, pernicious anemia, titers are generally < or =0.02 nmol/L.
-> For stiff-person syndrome, autoimmune encephalitis, cerebellitis, brainstem encephalitis, and myelitis, titers are generally > or =0.03 nmol/L.
-> For myasthenia gravis, Lambert-Eaton Syndrome, and dysautonomia, titers are < or =0.02 nmol/L.

(2) ELISA levels of GAD65 [Source: Genway/Mayo Clinic/Athena Labs]
-> Negative = <5.0 IU/mL
-> Positive = > 5.0 IU/mL

(3) RBA levels of GAD65 [Source: Quest]
-> Negative = ≤1.0 U/mL
-> Positive = >1.0 U/mL​

And my report says literally just this one line:

Glutamate Decarboxylase 65 Ab: 27.3 U/ML. [Reference range is < or = to 1.0 U/ML]
​

So, the logical way to read my report is that my lab is using method #3 above (highlighted in red), and therefore my reading of 27.3 is 27 times bigger than the threshold of 1.0. Quite scary. I would much prefer if my lab was using method #2 or the method described by @phoenix where positive result is >= 25.0 U/ML since these methods while still placing me as LADA, have a much smaller difference with the threshold. I guess I will still need to wait for my doctor's appointment in about 2 weeks and am hoping I am somehow reading this wrong...

Does my thinking make sense?

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bluedeep said:

Thanks for asking @CatLadyNZ. I am in my 40-s and discovered I have a problem about 6 weeks ago when on a routine blood test my fasting BG was 18.7. Quite a shock since I had a BMI of 25, am quite active and basically don't really consume much sugar other than fruit. But during that time my BG after meals was climbing to at the highest 29... Strange thing is I wasn't feeling it in the sense that I wasn't tired or feeling dizzy, or having blurred vision, or anything outside of extra thirst and urination. And rapid weight loss.

The last time I measured my BG before the very high reading was about 6 months ago and it was then 6.0. Basically I developed diabetes in the course of just a few months. Doing it so fast, I understand, is an indication for type 1.5. And had one other clear indication of type 1.5 which is that I lost 50 pounds in just 2 to 3 months. Now my BMI is 20 and am still having trouble gaining weight.

My doctor put me on metformin 2 times a day 1000 mg each. And I changed my diet and started being even more active than before. So, my BG started going down almost daily and about 2 weeks ago the fasting BG got down to around 7.0 and it has been fluctuating there ever since. Basically, all my daily readings are usually between 4.5 and 7.3. The metformin has helped. And also, I may be experiencing the honey moon period.

In spite of the very high BG readings, I never felt really sick in any way both now and before. And the BG is now more or less under control. But the whole rapid development, the massive weight loss and now the very high GAD64 Ab reading makes me worried. I am dreading the possibly that the diabetes I have may not be the only problem. Reading about very high GAD antibodies and all possible implications (including the ones outside diabetes) is quite an unpleasant ordeal right now...

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bluedeep said:

I've been reading about all sorts of other possible neurological complications that a high GAD65Ab test indicates. For example: high result means diabetes 1.5, but even higher result means potentially diseases such as SPS (http://www.medscape.com/viewarticle/751794).

There is a long list actually and I haven't read about all of them: http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/81596.

Quote from link above: "Antibodies directed against the 65-kd isoform of GAD (GAD65) are seen in a variety of autoimmune neurologic disorders including stiff-man (Moersch-Woltman) syndrome, autoimmune cerebellitis, brain stem encephalitis, seizure disorders, neuromyelitis optica and other myelopathies, myasthenia gravis, Lambert-Eaton syndrome, and dysautonomia."

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