Testing to establish a history of excessive alcohol use


Alcohol, despite being legal and widely available, is recognised as one of the most harmful of the drugs of abuse. Excessive use has a dramatic impact on a person’s social responsibility and behavior.

Alcohol only remains for around 24 to 48 hours in the blood, breath or even urine and it does not become incorporated into the hair at all as such, alcohol as a marker is worthless in trying to establish a history of use for more than 1 or 2 days. Several tests are available to help determine if there has been excessive drinking historically, but unfortunately none of these tests independently are very good at answering this question, making alcohol a difficult drug to test for and monitor.

Through extensive research and development, the Forensic Testing Service (FTS) now provide a new approach to providing the answers. Results derived from a menu of tests over time, produce a more accurate and reliable assessment of alcohol abuse and FTS then provide a clear and concise interpretation of all results in a report that is meaningful and easy to understand.

How do we define “excessive drinking?”

Excessive drinking is defined by the World Health Organisation to be drinking more than 60g of alcohol per day (slightly lower for women), for simplicity FTS use a definition of average units per week. To define the point at which drinking becomes excessive FTS use a general cut-off of >60 units per week for men and >55 units per week for women, which equates approximately to 4 or 5 pints of beer, 1 to 1.5 bottles of wine or one third of a bottle of spirits per day.

How do we differentiate excessive from acceptable drinking?

The testing used to identify excessive alcohol consumption depends on the application or purpose of the testing. For example, whether we are assessing levels that would impact on health, safety or social responsibility, although clearly these are all interrelated. There are two types of test that can be used.

Direct markers: These are produced as a direct result of exposure to alcohol and are therefore very specific to alcohol use. The two routine direct tests provided by FTS are EtG and FAEE, measured in hair to cover a 3 or 6 month history. For certain circumstances, which would be advised as required by FTS, alcohol and / or EtG can also be tested in urine to cover from 1 and up to a 4 day history.

Indirect markers: These are produced as a response to the toxicity of alcohol, causing impairment of normal body functions, particularly impairment of the liver. The routine indirect tests recommended by FTS are Blood tests for LFT’s, CDT, GGT-CDT ratio and MCV, generally to cover a 3 to 8 week history. However these markers can be influenced by other factors and are therefore not specific to alcohol and do not always respond to excessive alcohol use.

Importantly there is no single test that can provide all the answers, the results of any one of these tests independently are generally quite poor at differentiating normal from excessive alcohol use.

Recommended alcohol testing for best practice

The combined profile of blood tests and hair tests should be selected for all new cases where there is no reliable previous testing history.

Alcohol Profile:

  • Blood tests for: LFT, CDT, GGT-CDTr and MCV
  • Hair tests for: EtG and FAEE
  • Urine test for: EtG*

*A urine test for EtG is also included where it is necessary to establish complete abstinence from drinking.

The Alcohol Profile, together with a detailed history taken from the client, provides the best starting point to differentiate social drinkers from excessive alcohol users. This profile can be selected to cover the previous 3 or 6 months history and extended to 9 months in some circumstances. Importantly it also provides sufficient information to make a recommendation as to whether further testing is required, and if so provide a guide for the profile required and when this testing needs to be carried out.

Where this profile identifies potential issues or where on-going monitoring for alcohol use is required, then best practice is to carry out at least two further tests at 4 to 6 and 8 to12 weeks or on a rolling 6 weekly basis for as long as required as follows:

  • 1st Alcohol profile
  • 2nd Blood only Alcohol profile at 4 to 6 weeks
  • 3rd Full Alcohol profile at 8 to 12 weeks

FTS have demonstrated that following this alcohol-testing profile is the most reliable way to differentiate excessive from acceptable drinking and a case can then be resolved in a short and controlled time scale. This saves costs and ensures decisions are taken on the most reliable and clear evidence available.

Using only blood tests or hair tests individually cannot usually be relied upon or provide the detailed information required for clear and unambiguous interpretation and meaningful recommendations.

What if the client has little or no hair?

Where scalp hair is not available or is too short for optimal testing, then body hair or in some cases facial hair can be used as an alternative. However interpretation of EtG and FAEE testing is less precise and the results are not always definitive.

Testing body hair is also helpful in addition to scalp hair where scalp hair is shorter than optimal or where repetitive use of hair treatments may have compromised the reliability of the testing. FTS will advise on the best options as required.

What if the client has a needle phobia or poor veins?

FTS Collection Officers are very experienced and familiar with these difficult situations. Local topical anaesthetic can be used and also if necessary extra fine needles to minimise discomfort and ensure most blood collections succeed without causing anxiety to the client.

Why not just Hair Tests?

Hair tests, being direct Markers, are mostly specific to excessive alcohol use, particularly EtG and generally provide a good screening tool to identify excessive drinking. However for a variety of reasons it is extremely important not to rely on hair alone, for the following reasons:

A blunt instrument - Hair tests can only provide an average of alcohol consumption over approximate 3 or 6 months periods. Therefore they can be a “blunt instrument” when trying to establish changes in the pattern of alcohol use (increasing, maintenance of, or decreasing use).

Below is an example of the issues that can arise from using hair tests alone:

  • Client A drinks very heavily, over 100 units per week and subsequently stops or significantly reduces their drinking for the 6 to 8 weeks prior to testing.
  • Client B drinks excessively at around 60 to 70 units per week for the entire period of 12 or more weeks up to the point of testing.
  • Client C has been teetotal for several months but relapses and begins drinking heavily again, over 100 units per week for around 5 to 6 prior to testing.
  • Client D drinks at a dangerous level of >150 units per week, has for many years and is entirely dependant on alcohol.

Despite the very different drinking profiles these clients would generally produce the same Positive EtG and FAEE results and it would not be possible to differentiate one from the other. Clearly these are very different patterns of use, resulting in different recommendations and outcomes. Combining the use of blood markers, which can react quickly to changes in alcohol use, enables the Expert to differentiate between these profiles and provide appropriate recommendations to help the courts come to the right decision.

EtG and FAEE can provide different answers - FAEE and EtG are different with regards to their methods of incorporation into the hair, stability and distribution along the hair shaft, therefore these markers have different sensitivity and specificity profiles. FAEE migrates along the hair shaft away from the scalp over time concentrating in the older hair, EtG tends to be higher in recently grown hair, and therefore recent periods of reduced alcohol use or abstinence can cause the FAEE levels to fall more quickly than EtG, which can cause a discrepancy in the FAEE and EtG results in around 20% of cases.

External influences can produce misleading results - Hair is exposed to various external, environmental and genetic factors that can influence the presence or absence, or the levels of FAEE and/or EtG found in the hair. Different types of hair treatments and the frequency with which they are used have been shown to have a significant influence on the levels of either FAEE and/or EtG, causing the results to be understated or overstated, which, in the extreme, can give rise to False Positive or False Negative test results.

Furthermore these treatments affect EtG and FAEE very differently and therefore testing both markers is usually recommended particularly in women to provide a more reliable outcome. However even with the results of both EtG and FAEE it is important that they are interpreted in the context of blood test results, which are not exposed to the same external influences.

Scalp hair not always available or of sufficient length - Certain individuals do not have any scalp or even body hair for testing and scalp hair is not always long enough to provide the optimal 3 cm sample for EtG or the mandatory minimum 3 cm sample for FAEE testing, which is required for optimal results interpretation.

Summary - Because of the various issues described above, there are conflicts between FAEE and EtG results in more than 20% of cases leading to uncertainty. These conflicts can often be resolved by putting the results into context with the blood test results. Without the blood test results, in a significant number of cases, the results would remain inconclusive and no progress could be made without further testing, with the resulting wasted costs and time.

Why not just Blood Tests?

Blood tests are extremely well established and a significant amount of data has been accumulated over many years, hence they are well understood. Unlike hair tests they cannot be adulterated or influenced by external or environmental factors and they also provide shorter defined periods over which they can identify excessive alcohol use.

Certain blood markers can also provide an indication as to whether there may have been a previous history of chronic alcohol abuse with resulting liver damage, this is very helpful since it provides an indication as to how serious the alcohol abuse might be and whether this is deep-seated or a more normal transient pattern. It also helps to understand the risk of re-occurrence, therefore blood tests make an essential contribution to alcohol testing.

However being predominantly indirect markers they are less specific than hair tests, in that all the blood markers tested are affected by influences other than alcohol, with the exception of CDT, which has a very low false positive rate. Each marker is generally affected by different influences and therefore using a profile of several blood tests minimises this problem, but cannot eliminate it. Like the hair tests there is also inter-individual variability in response to these influences, therefore blood tests cannot always provide a reliable understanding of the amounts of alcohol consumed but become very useful when interpreted in the context of the results from hair tests.

Below are examples of the issues that can arise from using blood tests alone:

  • A range of commonly prescribed or pharmacy purchased medications such as Paracetamol and Statins can cause certain LFT’s to be raised above the normal range mimicking the effects of alcohol, certain diseases such as Hepatitis can also cause raised LFT’s like alcohol. If these results are taken out of context this can give rise to False Positive results.
  • CDT is more specific than the LFT’s and although it can become raised for other reasons, raised CDT is normally associated with excessive alcohol in >95% of cases. However it is less sensitive and is only raised in around 60% of males and 50% of women following excessive alcohol use over the recent 2 to 3 weeks. Again taken out of context this can give rise to False Negative results.
  • MCV (Mean Corpuscular Volume) is not a liver enzyme and is typically influenced by different factors than LFT’s and CDT, however as with the LFT’s and CDT it will not always be raised by excessive alcohol use and can become raised for certain conditions unrelated to alcohol. However when combined with the other blood markers it becomes a good indicator for excessive drinking.

Like hair testing, because of the various issues described above there are sometimes conflicts between the blood test results. When this occurs it can often be resolved by putting into context with the results from the hair tests. Without the addition of the hair tests, on a significant number of cases, the results would remain inconclusive.

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