dine were consumed, may last for several days or longer.
Prevalence
Use of phencyclidine or related substances ma y be taken as an estimate of the prevalence
of intoxication. Approximately 2.5% of the po pulation reports having ever used phency-
clidine. Among high school students, 2.3% of  12th graders report ever using phencycli-
dine, with 57% having used in the past 12 months. This represents an increase from prior
to 2011. Past-year use of ketamine, which is assessed separately from other substances, has
remained stable over time, with about 1.7% of 12th graders reporting use.
Diagnostic Markers 
Laboratory testing may be useful, as phencycl idine is detectable in urine for up to 8 days
following use, although the levels are only weakly associated with an individual’s clinical
presentation and may therefore not be useful for case management. Creatine phosphoki-
nase and aspartate aminotransfe rase levels may be elevated.
Functional Consequences of  Phencyclidine Intoxication
Phencyclidine intoxication produces extensiv e cardiovascular and neurological (e.g., sei-
zures, dystonias, dyskinesias, catalepsy, hypothermia or hyperthermia) toxicity.
Differential Diagnosis
In particular, in the absence of intact realit y testing (i.e., without in sight into any percep-
tual abnormalities), an additional diagno sis of phencyclidine-induced psychotic disorder
should be considered.
Other substance intoxication. Phencyclidine intoxication should be differentiated from
intoxication due to other su bstances, including other hallucinogens; amphetamine, co-