Additional CLIA-waived urine tests

In addition to a routine urinalysis, there are other tests that can be done on urine. Medical assistants can perform CLIA-waived urine tests, and some of those are discussed in the following sections. Urine can also be used for toxicology testing. It is important for anyone working with specimens for toxicology to have an understanding of how those specimens could potentially be adulterated and to understand the chain of command. This is also discussed in the following section.

Urine pregnancy testing

All pregnancy tests detect the presence of human chorionic gonadotropin (hCG), a hormone produced by the placenta and present in urine during pregnancy (see Procedure 32.7). After the fertilized egg has implanted in the uterus, the hCG levels in serum double every few days. This rapid rise occurs for approximately 7 weeks, and then the level begins to decline. Within 72 hours of delivery, the hormone disappears.

The most common type of test for pregnancy is the lateral flow immunoassay test. Many brands are available for laboratory use and are also available over the counter (OTC) for home use. These tests are sensitive enough to detect the presence of hCG in urine as early as 1 week after implantation, or 4 to 5 days before a missed menstrual period. The tests can be performed in as little as 5 minutes and are easy to interpret. CLIA-waived pregnancy tests or home pregnancy tests are read following the manufacturer’s instructions. Evaluating the results is often as simple as reading a color change. For optimum results, the test should be performed on a first-morning urine specimen because it is the most concentrated urine of the day.

The test is based on reactions that occur between antibodies and antigens. Antibodies are proteins formed in response to a specific antigen (e.g., paired like a lock and key). Antigens are foreign substances that initiate the production of antibodies. When antibodies and antigens come in contact, the antibody binds to the antigen. This makes the antigen unable to cause disease. (See Chapter 18 for more information on antibodies and antigens.)

The pregnancy test cartridge contains a membrane with an absorbent pad. The urine sample is pipetted into the sample well of the test cartridge. The urine then moves along the absorbent pad, reaching the test area on the membrane. The following reactions can occur:

• All samples (positive or negative) cause the control zone © line to turn blue. The presence of this line indicates that the test has been carried out correctly. If the C control zone does not show a color reaction, the test is considered invalid (incorrect) and must be repeated using another test device.
• In a positive sample, the hCG antigen attaches to the antibodies in the test zone (T), forming a pink line.
• In a negative sample, there is no hCG antigen to attach to the antibodies in the test zone (T), and no line forms.

The Quick Vue test is a lateral flow pregnancy test that can be performed on urine. It is used routinely in many POLs.

Ovulation testing

CLIA-waived lateral flow urine tests are available to predict ovulation for women attempting to conceive either naturally or using artificial insemination . During the menstrual cycle, luteinizing hormone (LH) remains at a relatively stable level. Approximately 14 days before menstruation, the body experiences the “LH surge,” a brief, rapid increase in LH. This surge triggers the release of an ovum (egg) from the ovary. Two to 3 days after the surge, the LH level returns to the base level. Conception is most likely to occur within 36 hours after the LH surge. The principle behind this test is similar to that of the pregnancy test. The absorbent membrane contains anti-LH antibodies. A positive test result indicates a urine LH level of 20 mIU/mL or higher. Testing usually is performed for 5 consecutive days in the middle of a woman’s cycle. Once the surge is detected, ovulation can be expected within 2 to 3 days.

Menopause testing

A woman is said to have reached menopause when she has not had a menstrual period for at least 12 months. The time before menopause, called perimenopause, can last for years, bringing with it uncomfortable symptoms such as irregular periods, hot flashes, vaginal dryness, and sleep problems.

Some of this may be due to an increase in follicle-stimulating hormone (FSH). Levels of FSH increase temporarily each month to stimulate the ovaries to produce an ovum (egg). When a woman enters menopause, the ovaries stop producing eggs, and the levels of FSH rise. CLIA-waived lateral flow tests detect FSH in the urine. A positive test result indicates that a woman may be in menopause; a negative test result, along with symptoms of menopause, may indicate that a woman is in perimenopause.

The qualitative lateral flow test should never be used to direct a woman to stop using birth control methods if she does not want to conceive. Pregnancy is still possible during perimenopause.

Commonly abused drugs and body retention times

Drug	Retention time
Alcohol	2–10 hours
Amphetamine	24–48 hours
Methamphetamine	3–5+ days
Barbiturates
— Phenobarbital	2–6 days
— Secobarbital	24 hours
Cocaine, cocaine metabolites	12 hours–3 days
Opiates, heroin, morphine	3–4 days
Phencyclidine (PCP)	3–7+ days
Marijuana (tetrahydrocannabinol metabolites)	2 days up to 11 weeks (for daily users)
Oxycodone	3 days