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Family Physician
Family Physician, Board Certified MRO
Category: Drug Testing
Satisfied Customers: 12816
Experience:  Medical Review Officer - Physician Trained and certified in drug test interpretation
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Will methadone show up in a blood test longer than in a

Customer Question

Will methadone show up in a blood test longer than in a urine test? If a person took methadone on a Monday (30 10s over a month and last one on a Monday) and tested positive on a urine test on a Friday. How long after that will that person test positive from a blood test. I have been told that methadone is detected longer in the urine as it metabloizes and then leave the blood, but I have also heard that because it attaches to proteins in the body, that once you stop taking it, it will leak back into the blood stream and then can be detected longer in a blood screen than a urine screen
Submitted: 5 years ago.
Category: Drug Testing
Expert:  Family Physician replied 5 years ago.
NO - most drugs/substances that are excreted in urine (such as methadone and methadone metabolites) are actually detectable for longer in urine than in blood.

It all comes down to concentrations; since the substances become more concentrated in urine, the substance remains above a detection threshold for longer periods of time.

This journal article looks at the detection periods of various drugs in blood/serum, urine and oral fluids (saliva). It does not specifically look at methadone, however as you can see, the detection periods for opiates heroin/morphine are 20 hours in blood, and up to 54 hours in urine.
http://labmed.yale.edu/Images/detection%20times%20in%20urine%20rev_tcm45-9313.pdf

However, there can be cases where a test would be negative in urine (because the urine was VERY dilute, or the person had just taken the drug and it had not yet been excreted in the urine) and positive in blood.