The blood alcohol test measures only the amount
of alcohol in the blood at the time the sample is taken. It does not show how
long you have been drinking or whether you have an alcohol use
Highway patrol officers in most states now have devices
(toximeters) that measure the breath alcohol levels of drivers they think are
drunk. A person charged with drunken driving who does not think the breath
analysis is accurate may ask for a blood alcohol test.
that passes between drinking alcohol and collecting the blood or breath sample
affects test results. The body continues to break down alcohol at a steady rate
after drinking. So the amount of alcohol you drink can be estimated by knowing
how much alcohol is present in your blood or breath and how much time has
passed since you had a drink. In general, your body is able to break down about
one drink per hour.
Things that affect how quickly the blood
alcohol level rises in the body include:
The number of drinks per hour. As you
increase the number of drinks per hour, your blood alcohol level steadily
The strength of alcohol (proof or percentage) in the
Your weight. The more you weigh, the more water is present
in your body, which dilutes the alcohol and lowers the blood alcohol
Your sex. Women's bodies usually have less water and more
fat than men's bodies. Alcohol does not go into fat cells as well as other
cells, so women tend to keep more alcohol in their blood than men do. Also, a
hormones may affect the breakdown of
Your age. One drink raises the blood alcohol level of an
older adult more than it does for a young adult.
Eating. Food in
the stomach absorbs some of the alcohol. The blood alcohol level will be higher
if you do not eat before or during drinking.
alcohol self-test can estimate your blood alcohol concentration. The handheld
device to measure breath alcohol is similar to, though not as precise as, the
type of test used by police for suspected drunk drivers. The breath alcohol
self-test offers one piece of information to help you make a safe decision
about drinking and driving. The safest decision is always not to drive if you
have been drinking. To learn more, see the topic
Self-Test for Breath Alcohol.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.