Urine Drug Testing Information

Urine drug testing is widely used for testing for opioids and illicit drugs. There are two types of urine drug testing: a screening test and a confirmatory test. The screening test uses an immunoassay to look for the parent drug and/or metabolite. Most UDTs screen for cocaine, marijuana, PCP, opiates, amphetamines, while some also test for benzodiazepines and methadone. The confirmatory urine drug test is done by gas Chromatography/mass spectrometry or high-performance liquid chromatography; this test is highly specific and is typically used when testing for the presence of a specific drug is needed.

Why urine drug testing?

• - monitor pharmacotherapy compliance;
• - identify individuals who may be at high risk;
• - a means of providing documentation to an agreed treatment plan.

Characteristics of urine

• temperature 90° F to 100 ° F
• pH 4.5 – 8
• creatinine concentration > 20 mg/dl
• specific gravity 1.003 – 1.030

Creatinine adjusted drug levels

The measured drug level is adjusted to the level of creatinine detected and multiplied by 100 mg/dl (patient's directly measured THC level x average creatinine excreted ÷ patient’s directly measured creatinine level = creatinine adjusted drug level).

Methods of urine drug testing

1. Immunoassay drug tests
• clarifies a substance as being present or absent;
• advantages:
  rapid turn around time;
  inexpensive;
  high sensitivity;
  
• limitations:
  cross-reactivity.
2. Point of care testing
• commercially available;
• does not require instrumentation;
• easy to use;
• limited number of tests;
• interpretation subjective;
• limited or deficient quality control.
3. POCT testing
• users of POCT devices should understand limitations;
• used should be trained;
• be aware of interferences from chemicals;
• consider cutoff(s) in selection of device;
• must use quality control material National Academy of Clinical Biochemistry (NACB).
4. Confirmatory testing
• gas chromatography/mass spectrometry (GC/MS):
  - the gold standard;
  - highly specific and sensitive.

Drugs and their metabolites

Drug class	Drug	Drug and/or metabolite
opiate	hydrocodone	hydrocodone hydromorphone
benzodiazapine	alprazolam	alprazolam alphahydroxylalprazolam
cocaine	cocaine	benzoylecgonine

Interpreting urine drug levels

• urine drug levels don’t indicate strength of drug being used
• urine drug levels don’t indicate how frequently the drug is used
• blood alcohol as a model

Urine drug test report
Drug not detected may be due to the following:

• patient didn’t take any of the medication;
• patient has not recently taken any of their medication;
• patient excretes medication and /or their metabolites at a different rate than normal;
• the test used was not sensitive enough;
• clerical error.

Detection times of drugs in urine
	Cutoff (ng/ml)	Days
Amphetamines	1000	< 5
Benzoylergamine after street doses of cocaine	300	2-3
Cannabinoids moderate smoker heavy smoker chronic smoker	50 50 50	5 10 < 28
Opiate	2000	1-2

The urine test is very reliable and is performed at most federally mandated facilities that require drug testing.