normal values in individuals who drink heavily— a change that is due to the direct toxic ef-
fects of alcohol on erythropoiesis. Although the MCV can be used  to help identify those who
drink heavily, it is a poor method of monitori ng abstinence because of the long half-life of
red blood cells. Liver function tests (e.g., alanine aminotransfe rase [ALT] and alkaline phos-
phatase) can reveal liver injury that is a co nsequence of heavy drinking. Other potential
markers of heavy drinking that are more nons pecific for alcohol but can help the clinician
think of the possible effects of alcohol include elevations in blood levels or lipids (e.g., tri-