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Dr. Abby
Dr. Abby, US Board Certified MD
Category: Medical
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Experience:  Family Physician practicing medicine for over 10 years, United States
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Will methadone show up in a blood test 42 days after last

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will methadone show up in a blood test 42 days after last use. I am fifty four year old and weigh one hundred and ten lbs.The last time I used any was on jan.7 2010. Prior to that I use about fitty mgs. for two days. Being tested for all prescibed meds. and non prescribed drugs.This is a complete blood test for everything including vitiam D etc.
Submitted: 7 years ago.
Category: Medical
Expert:  Dr. Abby replied 7 years ago.
Hello,

No, methadone will not show up 42 days after last use.

The half life of methadone ranges from 8-59 hours, meaning that 1/2 of the drug is eliminated from the body every 8-59 hours. So, if you use the upper range (59 hours), that means that every 2 1/2 days, one half of the amount that you took is removed from the body. So it should be removed from your body within about 7-12 days maximum.

Feel free to ask any follow up questions you may have,

Dr Abby


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Customer: replied 7 years ago.

I had taken a urine test at my doctors office and it had been two weeks atfer I had used methadone and it showed up positve for methadone.If I am correct blood tests show up more then a urine test. Why would I show up positive two weeks later for methadone for a urine test.The test this doctor uses is the very advanced one. I not sure what it is called, its something like a gastrospectromy ms/ms. These tests are costing me 1904.00 for eveytime I have to take one. I do not know if I have to pay extra for this question but I will ask you anyway and find out. Is it ethical for a doctor to lie to you about why a test is being taken? Tell you a test result is not back when you came in and it was but made you come but the next week for another one. Especailly since these test cost so much.

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Expert:  Dr. Abby replied 7 years ago.
First, you do not need to pay extra for this question. You have not accepted yet and it would all be included if you do accept.

Your doctor used a confirmatory test called a GCMS. (gas chromatography/mass spectrometry). This test identifies the exact drug that is present in the urine so that there are no false positives.

As to why you turned up positive 14 days after use...it is unusual. But, you probably just came in at the cutoff. If you had 100 mg in your system, then 2 1/2 days later you had 50 mg, then at 5 days you had 25, 7 1/2 days you had 12.5 mg, 10 days you had 6.25 mg, 12 1/2 days you had about 3 mg, 14 1/2 days you had about 1 1/2 mg. It depends on the sensitivity of the test.

I hope that makes sense...

As for the ethical part, if you are on pain medication and had a pain contract with your doctor, then he may be able to screen you whenever. He should be honest with you though, regarding results.

Feel free to ask any follow up questions you may have,

Dr Abby


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Customer: replied 7 years ago.

I am so sorry for asking you this you have been so wonderful. I don't know if I made my question clear enough for you. I stated I had used 50mg. of methadone. I used 50mg. one day and 50mg the next day making it a total of 100mg.Is this the same break down for blood test?I think on the 7th I took 20mg.then had taken the100mg two days prior to that. And yes thats what the test is called. Is this the same test used for blood test since he is using this lab for U.A. tests? Do they break down the same as stated above in a blood test? Thank you for being so helpful to me. I am sorry for asking you so many questions.My doctor and I don't have a good doctor patient relationship.Never listens to me about any concerns I have.

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Expert:  Dr. Abby replied 7 years ago.
I am confused...why are you asking about blood tests?
Usually, methadone is tested for in urine, which is what you had done.

Are you afraid that your doctor is going to test you for methadone with the upcoming test?
If this is the case, you will not test positive.
I believe that I gave you a fairly good assessment regarding the breakdown for urine testing..you took 20 then 50 then 50. It takes up to 2 1/2 days for 1/2 of the daily dosage to be removed by the urine.

Every person is different and metabolizes the drug differently.

I cannot predict exactly how your body breaks down methadone.
But you should not have a positive blood or urine test 42 days after your last ingestion.

Dr Abby

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Customer: replied 7 years ago.
I was given a blood test on the 22nd of feb. 2010 for anything not prescribed to me. I just wanted to let you know that yes I was given a blood test for everything in my system that does belong and does not belong. should have made this clear that blood test was given. Not a urine test.
Expert:  Dr. Abby replied 7 years ago.
I believe that your test on Feb. 22, if you did not use methadone after Jan. 7th. should not test positive for methadone.

It does not stay in your system that long.

Dr Abby

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