PtProtect® – Interpretation of Results
Promoting pain relief and preventing abuse of pain medications is a critical balancing act for clinicians.
For that reason, caution must be used in the interpretation of the opiate/opioids results, since commonly prescribed opiates (codeine) and opioids (hydrocodone and oxycodone) metabolize to active opiate and opioid drugs (codeine → morphine, hydrocodone → hydromorphone, and oxycodone → oxymorphone) which are also available by prescription.
Metabolic Considerations
Caution must be used in interpreting opiate and opioid results since commonly prescribed opiates (codeine) and opioids (hydrocodone and oxycodone) metabolize to active opiate and opioid drugs (codeine → morphine, hydrocodone → hydromorphone, and oxycodone → oxymorphone) which are also available by prescription.
In addition to the major metabolism that occurs in standard doses of opiate and opioids, when high doses of codeine or morphine are used in tolerant patients, “minor” metabolites can occur from commonly prescribed opioids (codeine → hydrocodone, and morphine → hydromorphone).
The complex biotransformation (metabolism) of opiates and opioids is shown in the diagram below.
Implications
Determining the source of a detected opiate/opioid can be difficult and requires clinical correlation.
Frequently Asked Questions
Why would a patient not have a drug present that was prescribed?
- Non-adherence
- Diversion
- Fast metabolizer
- Drug-induced metabolism (e.g. rifampin)
- Poor drug absorption (e.g. celiac disease)
- Diluted urine
Why would a patient have a drug present that was not prescribed?
- Normal opiate and opioid metabolite from a legitimate prescription
- Opiate and opioid metabolite found when high doses of codeine or morphine are used
- High-dose codeine can metabolize to hydrocodone
- High-dose morphine can metabolize to hydromorphone
- Prescription from another physician
- Medication obtained from spouse or friend
- Illicit use of drug obtained without prescription
What is the relationship between heroin and morphine in my patient’s results?
- Detection of 6-monoacetylmorphine is consistent with heroin use.
- Absence of 6-monoacetylmorphine does not rule out heroin use when morphine is present.
- Common reasons for the presence of morphine include a morphine prescription, codeine prescription (since codeine metabolizes to morphine), dietary poppy seeds and the use of heroin.
What is included in a report’s interpretive comments?
PtProtect reports provide interpretive comments that are based on prescribed medications and the analytical test results. We compare medications prescribed, medications detected and the ratio of metabolite to parent substance to facilitate your understanding of the test data.
An interpretive comment will also be included even when prescription medication use is:
- Undisclosed on your requisition or order
- Unknown to you
- Not currently part of the patient’s care plan under your supervision
Can I tell whether my patient has taken more (or less) than the dose of medication I prescribed?
Many aspects make it impractical to correlate urine drug concentration to a patient’s dosage. Using urine concentrations to monitor therapeutic levels is unreliable. Urine drug concentrations cannot determine:
- The amount of drug used
- Establish exactly when the last dose was taken
- Predict the source of the drug
What can I do if my patient’s results are discrepant?
When a clinician receives results inconsistent with prescription history, he or she has several options to consider:
- Counseling the patient
- Modifying the patient’s treatment plan
- Referring the patient to a substance abuse program
- Eliminating the patient from your practice
An instant test cup produced a negative result, while the PeaceHealth Laboratories test is positive. Why?
By nature, screens are limited in their specificity and sensitivity. Screens offer a generalized view of the existence of drugs that may be present in the patient. These limitations are particularly true when using instant cup drug screens, whether the indicators are on a dipstick or made part of the cup itself in some manner. For the highest accuracy and sensitivity, mass spectrometry testing should be used to verify all screen findings, whether positive or negative. See comparison of testing method sensitivities in Figure 1 to the right. All instant test cups should be returned to our laboratory for definitive testing.
Does the Pain Management Panel provide an interpretation for the source of drug metabolites both major and minor?
Several of the opiate/opioid analgesics (codeine, hydrocodone, oxycodone) have major and minor metabolites, which are pharmacologically active (morphine, hydromorphone, oxymorphone respectively) and are available as prescription drugs. Specific ratios of the metabolite to parent drug are utilized to determine whether the presence of these metabolites are actually coming from metabolism of the parent drug, are direct use of the individual drug or a combination of direct use and metabolism. This determination can be difficult, and caution must be used so that a patient is not falsely accused of abuse.
Does PeaceHealth Laboratories have clinical toxicologists available to provide expert interpretation and guidance for physicians and healthcare providers?
PeaceHealth Laboratories has experienced, board-certified clinical toxicologists available to answer questions concerning interpretation of PtProtect test results.
