Last publication date: March 2017

Chemical testing for doctors with alcohol and drug misuse concerns

Contents Section Page

Introduction 2

Overview of testing at the different stages 4

Guidance for health examiners and medical supervisors 8

- Your role and responsibilities 8

- What to do with the test results 10

- Changes to the normal testing schedule 11

FAQs for health examiners and medical supervisors 12

Annex A – The Science 14

- Testing for alcohol misuse 14

- Alcohol testing tables 19

- Testing for drug misuse 21

Annex B – Case studies 24

Annex C – Glossary of terms 26

2

Introduction

Who is this guidance for? This guidance is for use by GMC staff members (in particular case examiners, the Case Review Team and the Health Assessment Team) and GMC associates (health examiners and medical supervisors) when testing is needed for health assessments and medical supervision cases that involve the use of drugs and/or alcohol.

Our approach to testing

Chemical testing helps the GMC establish:

if and what substances have been/are being misused by the doctor (of particular help in health assessments)

if the doctor has complied with undertakings or conditions (of particular help for the purposes of medical supervision).

While many doctors involved in Fitness to Practise proceedings cooperate fully, sometimes individuals dependent on substances provide misleading or untruthful information about their use of drugs or alcohol; the reasons for this are complex. Test results can help the GMC understand the doctor’s level of insight and progress, and take reasoned decisions on whether or not the undertakings or conditions are sufficient to protect patient safety.

There are a number of benefits for doctors in agreeing to undergo testing. They can:

demonstrate that their health condition is in remission

demonstrate that they are compliant with restrictions

increase the doctor’s motivation to comply with restrictions

provide cumulative evidence that their health remains stable

provide evidence in support of the removal of restrictions.

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Being investigated or supervised by the GMC can be stressful and distressing for the doctor involved. However, aside from the protection health undertakings or conditions provide to patients from any risk posed by the doctor’s health, they can also provide a framework to support the doctor’s recovery from ill-health until he or she is sufficiently well to return to unrestricted practice.

Decisions about what testing to undertake will be made by those with the knowledge and expertise to do so. The GMC medical case examiner will be the primary decision maker, and their decisions will be informed by recommendations from the health examiner / medical supervisor.

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Overview of testing at different stages

Health Assessments

Initial health assessment

When we receive information suggesting that a doctor’s fitness to practise may be impaired through ill health, the case examiners may ask the doctor to have a health assessment.

A health assessment is one part of our wider investigation into the doctor’s fitness to practise. The doctor is examined by two health examiners, usually two consultant psychiatrists, who will each produce a report on the doctor’s health. When we have completed the assessment and any other investigations, a decision on the doctor’s fitness to practise is taken by two case examiners, one medical and one lay.

Reassessment

There are three scenarios where a doctor may be invited to a reassessment:

Before a review hearing.

For doctors with health-related undertakings who are being referred to a tribunal because of further concerns.

When we’re considering revoking a doctor’s undertakings, for assurance that they are fit to return to unrestricted practise.

Purpose of testing during health assessments

To establish what, if any, substances are being (mis)used by a doctor.

To provide a baseline measurement which could be used for reference during future supervision (eg raised levels during a known period of drinking can provide an indication of drinking if these levels are seen again).

For reassessments, to get up-to-date information about a doctor’s substance use ahead of a hearing or case examiner decision.

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What tests should be carried out?

This depends on the nature of the case. We’ll usually take the following approach, but case examiners can use their discretion to suggest additional or alternative tests. This also applies to the health examiners.

Type of case Test(s) Notes

Alcohol – first assessments and reassessments where doctor must limit consumption

Blood: FBC, LFT including GGT and CDT

Alcohol – reassessments where doctor must abstain

Blood: FBC, LFT including GGT and CDT

Also consider hair EtG test if the blood test results suggest any concerns.

If previous blood tests have been normal, and there are no other concerns, a blood test may be sufficient instead a of hair test.

Drug Hair: screen for common drugs of abuse

If the drug(s) of concern isn’t on the standard panel, this will need to be highlighted to the testing company.

In addition, the health examiner can also carry out these tests at the appointment at their discretion and if they have the necessary equipment:

Breathalyser

Saliva drug testing

Urine testing

All tests should be explained to the doctor before they are carried out and the sample taker should double-check that the doctor still consents to giving the sample.

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Medical Supervision Medical Supervision is the framework we use to monitor a doctor’s health and progress during a period of restricted practice. All doctors whose fitness to practise is impaired as a result of adverse physical or mental health will have a medical supervisor.

Principles

Tests will usually be carried out every 3 months or in accordance with the suggested testing regime. All tests will be arranged by the GMC.

Any testing done should take into account the start date of undertakings or conditions, and the period covered by the test results; this is particularly important in the interpretation of results.

If there is a period of repeatedly normal test results, and collateral information from treating healthcare professionals and the workplace confirms continued and consistent compliance with practice-related restrictions, the medical supervisor may suggest that testing should be less frequent.

Testing should be proportionate; if additional acceptable evidence is available from other parties (e.g. occupational health), this can be used, on case examiner advice, to avoid unnecessary duplication. The results should be kept under review to ensure ongoing suitability of the testing.

The testing schedule can be altered to address concerns; for example, more frequent testing, unannounced testing or different tests.

Purpose of testing during medical supervision

To act as a motivator and deterrent to the doctor

To establish whether any substances are continuing to be used

An opportunity for the doctor to positively evidence that they are safe to work through compliance with restrictions.

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Medical case examiners are the primary decision makers for any changes to testing type and frequency – they will consider medical supervisor recommendations as part of their decisions.

What tests should be carried out for medical supervision?

This depends on the nature of the case. At the start of the supervision period the GMC will set out an annual testing schedule based on the approach set out in the table below. The case owner will need to seek case examiner advice on the testing schedule if there is anything to suggest that a different approach should be followed (ie if the health assessment reports suggest a different approach, if the workplace is carrying out testing, or if there are any other concerns).

Case examiners can use their discretion to suggest additional or alternative tests. This also applies to the medical supervisors.

Type of case Test(s) Notes

Alcohol – limiting consumption

Blood: FBC, LFT including GGT and CDT

Every 3 months.

Alcohol - abstinence Blood: FBC, LFT including GGT and CDT

Every 3 months.

Hair tests (EtG) can also be carried out if blood tests are normal but there are still concerns about drinking. EtG testing only will be carried out (see Annex A for more information).

Drug Hair: screen for common drugs of abuse.

Every 3 months.

If the drug(s) of concern isn’t on the standard panel, this will need to be highlighted to the testing company.

In addition, the medical supervisor can also carry out these tests at the appointment at their discretion and if they have the necessary equipment:

Breathalyser

Saliva drug testing

Urine testing

All tests should be explained to the doctor before they are carried out and the sample taker should double-check that the doctor still consents to giving the sample.

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9

How we carry out testing

Guidance for health examiners and medical supervisors

Your role and responsibilities

Our independent testing company – Cansford Laboratories - will carry out all testing. This is for consistency, speed and cost effectiveness.

We will aim to have test results ready and disclosed to you before your appointment with the doctor. If they are, you should review these in advance and be ready to discuss them with the doctor.

Refer to Annex A for help interpreting the test results. If you need further help, get in touch with your GMC contact with any questions about what the results mean. They will pass on your queries to the testing company and get back to you with a response.

Explain the results to the doctor, their significance and how you plan to use them when writing your report. Don’t assume the doctor will understand the results – many will be unfamiliar with these types of tests.

If the results don’t line up with the doctor’s own report of their substance use, explain this to the doctor and consider whether any further investigations are needed – for example, a hair test may provide more information about alcohol consumption.

If appropriate you should: check with the GP or treating psychiatrist what medications are prescribed (prescription drugs may sometimes affect the interpretation of test results). check with the GP about other medical diagnoses (co-existing medical conditions may sometimes affect the interpretation of test results).

Remember that the doctor’s explanation for any test anomalies is important but should be cross-referenced with independent sources.

If the test results aren’t available at your appointment, you can still proceed with your assessment of the doctor. If the test results later change your opinion or are at odds with the doctor’s account, it may be helpful to phone the doctor to discuss these or ask further questions.

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If you think further tests are necessary, speak to your GMC contact who will arrange this.

In your report

Don’t submit your report until you have seen the test results.

Include your interpretation of the test results. Explain your findings fully and how they impact on your opinion and diagnosis.

Remember that testing is just one part of your overall assessment of the doctor’s fitness to practise. Although testing is important, results should not be considered in isolation from the overall clinical picture. The sensitivity and specificity of each test is an important consideration in interpretation of test results, especially when there is a difference between test results and the doctor’s self-reported drug and/or alcohol use. Concordance between test results can obviously help in the interpretation.

You should weigh the results against other collateral information but don’t just dismiss any results that you don’t understand or that don’t tally with the other information. Consider everything together and clearly justify your conclusions.

In addition for medical supervision:

Consider whether any other testing is taking place and whether this is a reliable source of testing – if it is, consider whether any change to the GMC testing schedule is needed (eg if the workplace is carrying out unannounced breath alcohol tests this may supersede the need for three-monthly blood tests).

If you receive test results from any other parties (eg the workplace) you should comment on and annex them to your progress report.

After a period of repeatedly normal test results, consider whether the current testing schedule is still appropriate.

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What to do with the test results We recognise that we need to carefully consider the potential effect of each interaction we have with doctors, particularly as disclosure of test results may be an added stressor and could be detrimental to their health.

In your role as a health examiner and medical supervisor you will see doctors whose test results suggest alcohol and/or non-prescribed drug use.

As a medical supervisor you have an on-going relationship with the doctors you supervise.

It’s important that you set out in your first appointment with the doctor what the approach is to testing and if test results are positive – use this checklist to help you.

First appointment checklist

Explain that testing will be carried out by Cansford, when and why, referring to the testing schedule sent to the doctor by the GMC case owner. The doctor will have already given consent for regular testing but it’s a good idea to check their understanding of this.

Explain the annual schedule of testing, and that the GMC will organise testing so that results are available before each appointment with them so you can discuss the results face to face.

Go through the doctor’s restrictions with them and check their understanding.

Explain what other information (from third parties) you will consider when arriving at your opinion on fitness to practise.

Encourage the doctor to be open and honest about any relapses during the supervision process.

Many doctors fear that positive test results will always result in them being sent to an interim orders tribunal or stopped from working which is not always the case. Explain that if you do ask them to stop working you will always let them know how long this is likely to be for, where possible, and/or what other information (such as negative test results) you will need to see before they can return to work.

Explain when you might suggest changes to the normal testing regime (see below).

Discuss your advice about attendance at support groups and/or prescribing as applicable.

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Changes to the normal testing schedule There may be occasions where different or ‘random’ testing is required: for example if the medical supervisor receives information from the workplace that suggests a relapse, if test results contain unexplained anomalies or if it is thought that the doctor is modifying their substance use to avoid detection through testing.

By ‘random’ testing we mean testing that is carried out outside of the normal testing schedule. For example, if hair testing is usually carried out every 3 months for alcohol, a blood test may be requested in between supervision appointments.

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FAQs for health examiners and medical supervisors

What if workplace testing is already taking place? Consider whether any existing workplace arrangements are sufficient to protect patient safety – for example, if a doctor’s workplace is carrying out frequent unannounced breath testing this may supersede the need for regular blood tests for alcohol. You should use your discretion – you may feel that additional tests would provide additional information to help inform your opinion on the doctor’s fitness to practise, in which case it would be appropriate for the GMC to continue with blood and/or hair tests.

In all cases, you should discuss this with your GMC contact so workplace arrangements can be considered. A case examiner will decide if regular GMC testing should be changed or paused in light of existing arrangements.

What if a doctor stops engaging or wants testing to be placed on hold?

There are some situations where the doctor may ask for testing to be paused, for example if they:

become more unwell and/or are not working in a clinical capacity

go abroad for a prolonged period of time

go on maternity leave.

This also applies to doctors who we have stopped monitoring after they give up their licence.

Testing should only be paused if the doctor is not working in a clinical capacity.

The medical supervisor should confirm with us that it may be appropriate to pause testing.

The GMC case owner should then get case examiner approval for testing to be stopped.

The GMC will write to the doctor to confirm that testing will be put on hold, either for a set period (eg if the doctor will be returning from abroad after six months) or indefinitely.

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The situation should be reviewed periodically – this will depend on the individual circumstances but at least every six months.

Before the doctor can return to work they must have approval to do so from the medical supervisor. There will need to be documented evidence of stability in the health condition which will be based on the results of testing and information from healthcare professionals.

We shouldn’t assume that a doctor will want to pause testing. Although testing is less relevant when a doctor isn’t working they may want to continue testing to demonstrate compliance with restrictions. The medical supervisor should explain the benefits of continuing testing, particularly if the doctor plans to return to clinical work in the future.

Are tests required when the index incident is not attributed to alcohol or drugs? Experience has shown that where the index incident or incidents were attributed by treating clinicians to a doctor’s depression or anxiety, drug and alcohol testing may still be relevant ie the full clinical picture may not yet have emerged.

If, during your assessment of the doctor you feel additional testing is needed you should explain this to the doctor stating what tests are needed and why. You should then get in touch with your GMC contact and they will seek case examiner approval to arrange this.

What if I have concerns that a doctor might misuse alcohol whilst restricted for drug misuse? Our case examiners do not routinely ask for testing for alcohol in cases where the doctor has restrictions relating to drug misuse. However, if you have concerns that a doctor may be misusing alcohol you should:

discuss your concerns with the doctor under supervision and advise us if their restrictions need changing to include a requirement to either limit their alcohol consumption or abstain absolutely from alcohol.

explain the reason(s) for being concerned about alcohol consumption in your progress report

discuss testing for alcohol consumption with us

recommend in your progress report that testing for alcohol is needed

if appropriate, provide an alcohol related (ICD10) diagnosis

The same principle applies in reverse for doctors with alcohol-related health conditions who might misuse drugs. There may be misuse of benzodiazepines or over the counter opiates in doctors with alcohol problems.

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Annex A - The Science

Test types explained

Testing for alcohol misuse A number of direct and indirect markers for alcohol consumption are available but they vary in their sensitivity, specificity, cost and level of intrusiveness. The tests should be interpreted taking into account the overall clinical picture and other evidence available.

Blood testing MCV (Mean Cell Volume) Elevated Mean Cell Volume (MCV) may indicate chronic excessive alcohol use. The estimated size of red blood cells (Mean Cell Volume) has been used for a long time as a marker for chronic excessive alcohol consumption. ‘Liver Function Tests’ (LFTs or aminotransferases) Elevated AST (aspartate transaminase) and ALT (alanine transaminase) may indicate longer term liver injury caused by chronic excessive alcohol intake.

Breath testing Breath testing relies on the evaporation of alcohol from the circulating blood into the alveolar spaces in the lungs during respiration. The quantity of alcohol present in expired air can be measured and is directly proportional to the concentration of alcohol in the blood. Because of the relatively short half-life of alcohol in blood, breath testing is most useful to confirm the very recent consumption of alcohol. Some substance misuse specialists have access to breathalyser kits and can therefore make use of this if a doctor attends an appointment and appears to be under the influence of alcohol.

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The so called ‘aminotransferases’ AST and ALT are cellular enzymes involved in amino acid metabolism; neither AST nor ALT are found exclusively in the liver. Both enzymes are used as a marker for longer term liver cell injury and are not affected by a single episode of drinking. Some experts believe that when aminotransferases are elevated, if the AST:ALT ratio is greater than 2.0, this is much more likely to be caused by alcohol excess (whereas in viral hepatitis the ratio is much lower due to a greater rise in ALT). GGT (Gamma GT or ƔGT or Gamma-glutamyl transpeptidase) Mild elevations of serum GGT are due to enzyme induction. Higher levels of serum GGT are believed to relate to liver cell damage. Normalisation can occur within 1 or 2 weeks if the elevation was mild. Decline from higher levels takes longer, even up to 6 weeks. GGT is generally considered more useful than the aminotransferases as a marker for alcohol consumption and has been used for a long time as a biochemical marker. Although GGT is present in liver cell membranes it is also found in other sites (e.g. pancreas) so can be affected by diseases of other organs. CDT (Carbohydrate Deficient Transferrin) Elevated CDT may indicate excess alcohol consumption within 2 weeks of testing. Transferrin is a blood protein used to transport iron which undergoes further modification by the addition of multiple carbohydrate chains. Excessive alcohol intake can affect transferrin so that there are less carbohydrate chains incorporated per protein molecule – therefore producing ‘carbohydrate deficient’ transferrin. The percentage of carbohydrate deficient transferrin molecules can be calculated in the lab. Individuals misusing alcohol typically have a higher proportion of transferrin as CDT (some labs specify >1.6% but the cut-off value may vary). An elevated CDT result is said to suggest the consumption of approx. 8-10 units or of alcohol or more on several consecutive days within approx. 2 weeks of the test being carried out. There is a rare genetic anomaly where the CDT is deficient in carbohydrate (about 1% of the population). If %CDT was elevated during a period of known abstinence, the doctor under testing might be such a case. However, if at any time a normal %CDT is documented, then the doctor is not carrying that anomaly.

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Hair testing for alcohol use General principles Metabolites of alcohol can be detected in hair relatively soon after consumption. These metabolites are incorporated into hair from the root but also in significant quantities from sebum and sweat (coating the hair). It is possible to use hair testing to detect the misuse of alcohol over a prolonged period (e.g. a 0-3cm sample of scalp hair represents approx. 3 months of possible exposure to alcohol). It is possible to segment hair samples into smaller sections (typically 1cm lengths) for EtG testing, to provide extra information about differing alcohol levels in approximately each month covered by the entire sample. However, this is not something that the GMC currently routinely does. This type of testing is useful during supervision but may be felt as intrusive as an adequate sample of hair, collected in the appropriate way, is required by the laboratory to provide meaningful results (the current GMC provider requires approximately 75 hairs). The Society of Hair Testing (SoHT) recommends caution when interpreting hair test results done on less than 3cm or more than 6cm of hair. Washing and treating with hair products can affect the concentrations of metabolites (particularly of EtG) found in samples and there is a gradual ‘leaching’ of the metabolites over time. The colour and thickness of hair also affects its ability to incorporate metabolites and it is useful for the laboratory to understand if the hair has been treated with chemicals. Hair testing for alcohol is based on tests for EtG (ethyl glucuronide) and FAEE (fatty acid ethyl esters; specifically ethyl palmitate in the most recent SoHT consensus); both are metabolites of alcohol. Testing relies on sophisticated and expensive technology that uses a chromatography-mass spectrometry technique. The testing makes it possible to measure very small amounts of chemicals, such as the metabolites of alcohol, in hair. Because hair testing is perceived as more intrusive than blood testing, the GMC does not routinely request hair testing for alcohol. However, if a medical supervisor considers that hair testing would be useful in a particular case, or if the level of concern about relapse is high, this should be discussed with the GMC office.

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Hair tests: EtG (ethyl glucuronide) EtG is the main test used in hair testing to assess alcohol consumption, and the GMC does not routinely test FAEEs. The latest Society of Hair Testing consensus statement (adopted in August 2016) agrees that levels of EtG below 7pg/ mg does not contradict self-reported abstinence of a person during the corresponding time period before sampling. That a concentration ≥7 pg/ mg of EtG in the proximal scalp hair up to 6 cm strongly suggests repeated alcohol consumption. The consensus view was that a positive EtG result ≥ 7pg/mg cannot be overruled by a negative FAEE result. Furthermore they stated: that a concentration of >30 pg/ mg EtGin the proximal scalp hair up to 6 cm strongly suggests chronic excessive alcohol consumption. Body Hair The consensus statement also stated that the same cut-off concentration levels can be used for non-head hair with the exception of axillary hair which is not suitable for EtG measurement. However the possibilities of a longer time period represented by non-head hair and of a higher sensitivity of pubic hair should be considered in interpretation. FAEE (fatty acid ethyl esters) The Society of Hair Testing also concluded that FAEE alone is not recommended to determine abstinence from ethanol but can be used in cases of suspected false negative EtG results (eg when the hair has been bleached or treated so that EtG levels may have been reduced), applying an ethyl palmitate cutoff concentration of 0.12 ng/mg for a 0-3 cm proximal scalp hair segment or 0.15 ng/mg for a 0-6 cm proximal scalp hair segment. . They also stated that a positive FAEE result combined with an EtG below 7 pg/mg result does not clearly disprove abstinence, but indicates the need for further monitoring. The full consensus statement can be viewed at: http://www.soht.org/images/pdf/Revision%202016_Alcoholmarkers.pdf

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Nail testing for alcohol use Nails and hair are both made of keratin and the metabolites of alcohol (and other drugs) are incorporated into nails from the germinal matrix and the nail bed. Nail clippings can therefore provide evidence of exposure to alcohol (and other drugs). However, false positive results may arise as a result of environmental exposure rather than ingestion. It is also important to note that the slower and more variable growth rate of nails makes it difficult to establish a ‘time line’ for drug and alcohol misuse by using this method. Other methods for detecting alcohol use A number of other markers for alcohol misuse are available. For example, PEth (phosphatidylethanol) is a blood test which is claimed to be more reliable than CDT as a marker for recent alcohol consumption. This is not currently used routinely by the GMC but we are watching the development of the test with interest. It is possible to test for the metabolites of alcohol in urine samples as this gives a longer ‘window’ for detection. The testing is expensive and is not routinely used by the GMC. If a health examiner or medical supervisor considers that other forms of testing would be useful in a particular case, this should be discussed with the GMC office.

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Alcohol Testing Tables

Testing that may suggest excess consumption of alcohol. ‘Heavy drinking likely’ (eg 60g ethanol/day=7-8units regularly in past 2+weeks)

Serum %CDT >1.6

Serum GGT above upper lab ‘normal’

Blood MCV above upper lab ‘normal’

Hair EtG >30pg/mg (ref 1)

(Use if EtG unexpectedly negative) Hair FAEE *

False neg: 20-40% 40% 70% 19% -40% Frequent shampoos; Bleaching; colouring. Other? (ref 5,6)

23%

False pos: 1-5% rare genetic anomaly; pregnancy; severe liver disease (ref 2,6)

Many non-alcohol causes: obesity; liver disease; some medications.

Medical disorders (eg macrocytic anaemia; hypothyroidism; folate deficiency) and anti-convulsants

3% Herbal hair lotions? Renal disease(ref 4) (?test serum creatinine in all cases)

?10% includes use of alcohol- containing hair lotions

Return to normal

2-4 weeks abstinence

2-6 weeks abstinence depending on starting level

2-3 months depending on starting level

Remains ‘pos’ until new hair has replaced hair growing before heavy drinking ceased

Usefulness If %CDT had been elevated when drinking was known to be heavy, eg at first GMC assessment, then normalisation supports cessation of heavy drinking.

If elevated when drinking heavily, normalisation supports cessation of heavy drinking. Reduction may be seen within the normal range, and indicates declining consumption.

Raised MCV without other medical explanation and normal CDT and enzymes, suggest heavy drinking up to a month ago

1. Allows a retrospective view of a period when blood tests were not done. 2. When a medical disorder or a medication confound interpretation of blood tests 3. For confirmation that blood testing has been working as our primary method of assurance.

*ethyl palmitate cut-off concentration of 0.12 ng/mg for a 0-3 cm proximal scalp hair segment or 0.15 ng/mg for a 0-6 cm proximal scalp hair segment.

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Testing to check self-reports of abstinence NB: Normalisation of blood tests (enzymes, MCV) supports but cannot prove abstinence

Hair EtG < 7pg/mg

Unannounced breath testing zero

Whole blood PEth* (<0.04ng/ml)

%CDT <1.6

Risk of giving false support to self-report of abstinence

Probably common viz: Some volunteers drinking 150g/week were <7 (ref 7) (EtG might be reduced by shampooing)

Common Because alcohol only detected in breath for some hours: 24 hrs for heavy, 2-3 hrs for light drinking

Possible: a single dose of ethanol might not always produce raised PEth (ref 8). Ethanol consumed several days ago might not show (ref 9).

High: %CDT is often normal in drinkers

Risk of leading to false rejection of self-report of abstinence

Probably uncommon (volunteer studies show all abstainers had <7pg/mg - ref 7)

Never – if abstinence is claimed, any +ve breath test = rejection of claim (mouth-wash excuse? – rinse mouth and repeat).

?Zero (Theoretically, abstainers for past ‘month’ cannot have PEth >0.01ng/ml - ref 9).

Almost zero; if %CDT is raised, then this disproves a claim of abstinence (except extremely rare genetic anomaly, and if a previous record showed a normal CDT, then raised means drinking)

Usefulness Logistically tricky, but can absolutely disprove claim of abstinence

Any raised PEth disproves abstinence (ref 9)

Worth doing, especially if previous records are available. A CDT result higher than previously, but still within range, could suggest a relapse into drinking.

*Phosphatidylethanol: Mean half-life after single dose of ethanol 4.6 days (range 1-13). This type of testing isn’t typically carried out for GMC purposes.

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Testing for drug misuse

Urine Testing for Drug Use

Urine testing remains a standard method of testing in some clinics. It is inexpensive but many substances are present in urine for a very short period making detection difficult (with exceptions such as cannabinoids and benzodiazepines). A negative sample for some drugs may only provide assurance that no substance use has occurred within 24-48 hours.

Some drugs such as GHB and GBL are so quickly metabolised that they are soon undetectable in urine.

This type of testing provides less historical information about drug use when compared to hair testing. This method is rarely used by the GMC.

Saliva Testing for Drug Use

Testing of saliva is non-invasive and the sample is easy to collect; it has become more widely used in recent years. There is a correlation between plasma levels of a drug and its concentration on saliva – this means that drugs that are rapidly excreted have a narrow window of detection (usually only up to 24 hours). This method is rarely used by the GMC.

Blood Testing for Drug Use

Blood samples can be used to determine some types of drug use. As with urine, drugs may be detectable in the bloodstream for a short period of time (24-48 hours) and may not a reliable indicator of long term misuse or abstinence.

This method is rarely used by the GMC.

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Hair Testing for Drug Use

General principles

Drugs and their metabolites are deposited in the root of the hair soon after consumption and move with the hair as it ‘grows’. Scalp hair grows at an average of 1cm per month and the effect of this is that hair strands show the chronological traces of exposure to drugs. It is therefore possible to use hair testing as a ‘timeline’ to show the use of drugs over a prolonged period (e.g. a 0-3cm sample of scalp hair represents approx. 3 months of possible exposure to drugs – be aware that this growth rate is an average only, so a 3cm sample might actually cover more or less than 3 months).

This type of testing is useful during supervision but is potentially intrusive as an adequate sample of hair, collected in the appropriate way, is required by the laboratory to provide meaningful results (the GMC’s current provider collects approximately 75 hairs).

Washing and treating with hair products can affect the concentrations of drugs and their metabolites found in samples and there is a gradual ‘leaching’ of substances over time. The colour and thickness of hair also affects its ability to incorporate metabolites and it is useful for the laboratory to understand if the hair has been treated with chemicals.

Laboratories will wash the hair when it is received and retain the liquid so that this can also be tested for traces of drugs (this is useful when a testing subject claims to have been present in a room where others were using drugs but did not personally ingest the drug).

It is not usually necessary to ask for segmented hair testing which is very expensive and does not provide useful information for GMC purposes (segmented testing is where the hair is cut into 1cm segments to give a more accurate idea of when drug use actually took place within a longer period). If a medical supervisor considers that segmented hair testing would be useful in a particular case, this should be discussed with the GMC office.

Body Hair

It is possible to test body hair for the presence of drugs and their metabolites where no scalp hair (or insufficient hair) is available for sampling.

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Nail testing for drug misuse

Nails and hair are both made of keratin and drugs and their metabolites are incorporated into nails from the germinal matrix and the nail bed. Nail clippings can therefore provide evidence of exposure to drugs and their metabolites. However, due to the slower and more variable growth rate of nails, it is not usually possible to use nails to establish a ‘time line’ for drug misuse.

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Annex B – Case studies Always bear in mind that test results must be viewed in the context of the whole clinical history and current situation.

Case 1 Examination: was elevated GGT due to venlafaxine?

Dr X, female, age 30, previous drink-drive conviction; unreliable work attendance; intoxicated at work, current GMC suspension under review at the doctor’s request. Claims abstinent for 9 months having undergone a 3 month residential treatment.

serum GGT elevated (75u/l). Dr X’s lawyer claims it was due to venlafaxine, 225 mg/day, that she has taken for 4 years. %CDT, AST and MCV all normal.

GP records: shortly after 3 month residential treatment, when taking venlafaxine 225mg, serum GGT was 30u/l, GP recorded at that date ‘abstinent’.

Interpretation: The raised GGT strongly suggests excessive drinking.

Subsequently a 3cm hair sample was taken:

EtG 107pg/mg (excessive consumption = > 30pg/mg)

Interpretation: excessive consumption

Examiner’s opinion (considering all available information): ‘not fit to practise’ because of continuing excessive consumption in someone with established alcohol dependence, with on-going denial.

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Case 2 Supervision: An unexpected positive hair test

A doctor with a history of forging prescriptions for opiates has had clear hair test results for first year with undertakings to abstain from all non-prescribed psychoactive substances. Recent sample of 3 cm hair shows opiates. She claims she had an anaesthetic for minor surgical intervention 3 months ago. The Medical Supervisor obtains a copy of the surgical discharge letter which confirms that post–operative morphine was prescribed.

The test is repeated on 3 cm hair at 4 months post-surgery and is clear.

Interpretation: it is accepted that she did not relapse into illicit opiate use.

Case 3 Supervision: Depression, but elevated GGT

Dr Y, female age 35, repeated failure to complete letters and reports; diagnosed major depressive disorder; fitness to practise investigation led to undertakings including to remain in treatment and limit alcohol consumption to within guidelines of the Chief Medical Officers, or abstain if medical supervisor recommended abstinence. Dr Y is currently taking maximum dose of a tricyclic antidepressant.

No blood tests in GP records or done at initial assessment At first supervision appointment, serum GGT elevated 90u/l (MCV and %CDT not

elevated) Advised to cut down or stop drinking Successive reduction of GGT to around upper limit of normal (ULN) during 6

months; work performance, mood good. Interpretation: the doctor is drinking above CMO’s guidelines

Examiner recommended no change in undertakings, but undertakings to be more strictly observed by the doctor.

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Annex C - Glossary of terms

Specific and sensitive A highly sensitive test means that there are few false negative results, and thus fewer cases of the condition are missed. The specificity of a test is its ability to designate an individual who does not have a condition as negative. A highly specific test means that there are few false positive results.

False negative The test failed to identify someone who was drinking excessively.

False positive The test wrongly identified someone as drinking excessively.