Google Answers Logo
View Question
Q: Laboratory urine toxicology testing error for alcohol ( Answered,   1 Comment )
Subject: Laboratory urine toxicology testing error for alcohol
Category: Science
Asked by: nose2e-ga
List Price: $75.00
Posted: 15 Jun 2004 23:26 PDT
Expires: 15 Jul 2004 23:26 PDT
Question ID: 361737
I'm told I tested positive for alcohol "unequivically", but know there
was no alcohol intake on my part.  What are the most probable sourses
of error, given that the test is highly sensitive and specific? 
Technical error of some sort comes to mind, and I am curious about the
actual incidence of false results due to technical error (including
mishandling of the specimen)in today's large metropolitan labs? 
(Dynacare in Seattle)

Request for Question Clarification by umiat-ga on 15 Jun 2004 23:33 PDT
What type of alcohol test did you have?

Request for Question Clarification by umiat-ga on 15 Jun 2004 23:40 PDT
Sorry....I see it was a urine test. It's late!
Subject: Re: Laboratory urine toxicology testing error for alcohol
Answered By: umiat-ga on 16 Jun 2004 00:53 PDT
Hello, nose2e-ga!

I have found a few references to inaccuracies in urine alcohol
testing, but I don't know if they apply to your situation. You have
said that you consumed absolutely no alcohol. Does that mean that you
had not consumed any alcohol for a long while (weeks or months?) or
within the past day or two?

There are instances where high levels of sugar or acetone in the urine
can result in false positives for alcohol content. If you suspect this
could be the case, it might be wise to have a medical check-up to see
if you have any abnormalities in urine composition.

There is reference to the fact that laboratory error can result in
false positives for alcohol due to contaminated equipment as well as
the introduction of air into the sample. I suppose it is also a
possibility that your sample could have been mislabeled!

While there is a lot of information regarding false positives and
laboratory inaccuracies for other types of drug tests, the false
results pertaining to urine testing for alcohol are less common.

I have found no specific complaints about false positives or sloppy
practices recorded against Dynacare Labs, specifically.


The following article provides a good overview of the types of alcohol
tests and the potential for false positives:

"ALCOHOL INTOXICATION TESTING." (Last updated: 01/06/04)

Urine Tests
"Urine normally contains about 1.3 times as much alcohol as blood, but
attempts to relate this to BAC depend on a number of bladder
conditions. If alcohol is consumed with a full bladder (the person has
not voided themselves), the test would produce a false negative
(inaccurately underestimate). If the person consumed alcohol with an
empty bladder and had not voided, the test would produce a false
positive (inaccurately overestimate). Urinalysis tests, most of the
time, are not favorable to the defendant. Higher concentrations of
alcohol in urine will occur over a longer period of time than in

"Law enforcement practice is to take two (2) samples, at 30-minute
intervals, preferably the latter sample after the bladder has been
emptied. Again, precautions must be made to add preservative and keep
the samples from exposure to light and heat. Urinalysis requires a bit
more sophisticated laboratory equipment than for blood testing. One of
three (3) laboratory methods are used: (1) chemical tests; (2)
biochemical tests; and (3) gas chromatography. Gas chromatography is
the most widely used because it can distinguish alcohol from ketones
and aldehydes (a problem that exists with diabetics and people with
other disorders that blood tests are not capable of controlling for).
While chromatography produces a printout and lends itself to
quantitative analysis, it always requires the expert testimony of a
scientist to be admissible in court. This is because chromatography
results are subject to both quantitative and qualitative

"It's important that police departments choose professional,
high-quality vendors to get their supplies (ampoules, vials,
preservatives, chemicals) from. At a minimum, there should be lot
numbers on each and every product which indicates manufacturer testing
and quality control procedures."

"It's also important that packaging and preservation of evidence be
consistent. The FBI has taken the lead in proposing standards (paper
or plastic), but some laboratories have their own preferences, and
police departments often run out of certain supplies and make do with
what's on hand (which should be avoided). Bottled specimens sent to
any lab should also have expiration dates on them, following whatever
guidelines are listed on the preservative's brochure. There should
also be independent corroboration (a statement by witnesses) of the
sample being collected, packaged, and mailed out (chain of evidence)."

Laboratory Quality
"Laboratories themselves, in order to be considered "professional",
must adhere to rigorous internal and external controls. Externally,
they should be site visited or audited by outsiders on a regular basis
as part of a certification or accreditation process. Internally, they
should have excellent record-keeping and quality controls. It must be
assured that all chemical reagents are fresh as things like
dichromates and permanganates tend to have short shelf life.
Instruments must be calibrated and standardized (using equilibrator
solutions) after every use.  Instruments, syringes, vials, and flasks
used in alcohol testing should never be cleaned or sterilized in
alcohol solutions. Boiling, likewise, will often trap alcohol-related
impurities or distillates into the equipment. Containers must not be
contaminated with foreign substances, and this includes the air.

* Exposure to air not only contributes to putrefaction of alcohol
samples but transmits oxidizable organic materials that may produce
false positives."


Though the following information is from a "pass the drug test" site,
the following excerpts on alcohol tests are informative:

From "Pass Any Drug Test."

Q. "Can the alcohol urine test detect alcohol in my urine even if I'm
no longer intoxicated?

"Yes. Alcohol can show up the morning after you have been drinking
even if you no longer are intoxicated.  Luckily, alcohol clears your
system much quicker than other drugs.  To get a roundabout figure of
how long you will test positive for alcohol in the urine, figure a
little over an hour for each one ounce drink (two hours if you want to
be really safe).  So, if you drank five 1-ounce shots of crown and two
regular-strength mixed drinks and you stopped drinking by 11:00 p.m.,
you should probably pass your alcohol urine test by 8 or 9 a.m. the
next morning and will definitely pass by noon or 1 p.m."

Q. "What is the difference between an EMIT alcohol urine screen and a
GC/MS alcohol urine test?"
"The EMIT drug and alcohol urine screen is a quick (sometimes
inaccurate) test which can be done on-site and is often used to screen
the urine samples. Those samples that test positive for the EMIT drug
and alcohol urine screen should be sent to an actual laboratory for a
more expensive, but more accurate, GC/MS testing.  Sometimes, in the
interest of saving money, only the EMIT drug and alcohol urine screen
is used. For more information on the drug and alcohol urine test see
our drug testing information and technical aspects of drug tests."

Q. "I've heard about diabetics testing positive on the alcohol urine
test even if they don't drink. Is this true?"

"It can be in some cases. Diabetics have glucose in their urine. If
the diabetic also has a yeast infection, a bladder infection or
another bacterial infection, the yeast or bacteria may start to feed
on the glucose. Yeast and bacteria produce ethanol as a biproduct when
feeding off of sugars. (This is also the same process used to make
alcohol in the first place.  Kind of fun to think that every time you
have a drink you're gulping down a whole slew of yeast droppings.) In
any case, this  yeast-biproduct, ethanol, is what is tested for in the
alcohol urine test. So yes, if a diabetic has the right sort of
bacterial or yeast infection, they can test positive for alcohol even
if they have never had a drop of alcohol in their life."


"Alcohol Testing." Advanced Safety Devices.

Urine Alcohol Testing

"Although urine alcohol testing will indicate the presence of alcohol
in a person's body, it will not indicate an individual's current
condition. Once consumed, alcohol enters the blood through the stomach
within 15 minutes, causing immediate impairment. It is then
metabolized by the body and, after 1 to 2 hours, will begin to show
up in the urine. Therefore, urine alcohol does not measure a true
condition of the person. The results indicate the person's condition
several hours before."

"Additionally, urine alcohol concentration does not directly
correspond to blood alcohol concentration. Urine alcohol concentration
will vary depending on the person's metabolism and the amount of fluid
in his system. For instance, a person who is slightly dehydrated will
tend to have a higher alcohol concentration in his urine than someone
who has a normal level of fluid in his system."

False reading:

* "At least one study has indicated that a false positive for urine
alcohol can occur. High levels of sugar and acetone in the body can
cause fermentation in the urine, creating a false positive for urine
alcohol. All things considered, the urine alcohol test is the least
preferred or perhaps accurate test available for alcohol testing."


Various physical conditions can lead to a high level of acetone in the
urine. A simple urine test at a doctor's office will reveal whether
this is a problem for you.

From "Ketones - urine." Medline Plus.

Acetone in the Urine: (Ketone bodies - urine; Urine ketones: acetone,
acetoacetic acid, and beta-hydroxybutyric acid )

A positive test may indicate:
* metabolic abnormalities, including uncontrolled diabetes or glycogen storage 
* abnormal nutritional conditions, including starvation, fasting, anorexia, 
  high protein or low carbohydrate diets 

* protracted vomiting, including hyperemesis gravidarum  

* disorders of increased metabolism, including hyperthyroidism, fever, acute 
  or severe illness, burns, pregnancy, lactation or following surgery 


 I hope this information is helpful. I recommend that you get a
physical checkup and have a urine test performed at a doctor's office
to measure for sugars and acetone in your urine. You may have an
underlying medical condition or nutritional deficit that requires

 If I can clarify anything further for you, please let me know.

Good luck!

Google Search Strategy
alcohol urine tests
inaccuracies in urine test +alcohol
alcohol urine testing "false positives"
causes for error in alcohol urine testing
"alcohol urine tests"
complaints against Dynacare lab +Seattle
acetone in urine
false readings at drug and alcohol laboratories

Clarification of Answer by umiat-ga on 18 Jun 2004 13:27 PDT
Due to Mathtalk's comments below, I want to reiterate that there are
other relevant portions in this answer to your question about
falsified readings for alcohol content in the urine. Yes, sugar in the
blood due to diabetes in one reason. However, at this point, you have
mentioned no inclination toward diabetes. Therefore, the references to
acetone levels in the urine (which can occur aside from diabetes) as
well as laboratory contamination of specimens are also not to be

Subject: Re: Laboratory urine toxicology testing error for alcohol
From: mathtalk-ga on 18 Jun 2004 09:04 PDT
Under the assumption that a person has not consumed any alcohol, the
relevant portion of umiat-ga's Answer is the brief section on

The blood sugar excreted in a diabetic's urine will tend to ferment
_after_ the sample is taken unless a preservative is added to prevent
this.   So it is not necessarily a matter of a person having a yeast

For a legal case in which some the medical and scientific aspects of
this are presented, see here:

regards, mathtalk-ga

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy