Codeine metabolite concentration (serum/plasma)

Why This Test Is Done

Your healthcare provider may order this test if you’re taking codeine or similar medications, especially if you have kidney issues, liver problems, or are taking other drugs that interact with codeine. It can also be used to monitor how your body responds to these medications over time.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm or vein to draw a blood sample. It usually takes a few minutes, and you may feel a brief pinch. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Higher-than-normal levels might suggest your body isn’t breaking down codeine well, which could increase side effects like drowsiness or breathing difficulties. Lower-than-normal levels might indicate your body is processing codeine too quickly, which could reduce its effectiveness.

Common Causes of Abnormal Results

Factors that could affect your results include kidney or liver disease, other medications you’re taking, genetics (how your body processes drugs), and whether you’ve recently taken codeine or similar drugs.