Experts weigh in on hCG testing

Feb. 1, 2011

Leonard Levin, MS, MBA, RM(NRCM), M(ASCP),
Administrative Director of Laboratory Services, Capital Health,
Trenton, NJ

More than pregnancy testing

In addition to testing for pregnancy and tumors, hCG testing is useful in screening for chromosomal abnormalities in the fetus such as Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18). We receive requests for the triple and quadruple maternal screens, which include hCG, alpha-fetoprotein (AFP), unconjugated estriol, and for the quadruple screen, inhibin A. During the second trimester of pregnancy, hCG levels are elevated in Down syndrome and low in Edwards syndrome. Studies have found that hCG testing alone can detect 40% of Down syndrome cases in the second trimester, while the addition of AFP and unconjugated estriol increases the sensitivity to 60%, and inhibin A further elevates the detection rate to 70%. There is also a first-trimester maternal screen that includes testing for hyperglycosylated hCG, or HhCG, pregnancy-associated plasma protein-A, or PAPP-A, and nuchal translucency (performed by ultrasonography). During the first trimester, HhCG testing detects 80% of Down syndrome cases.

Appeal of at-home testing

At-home testing appeals to the general public first because of convenience, cost, and confidentiality. Although healthcare providers are well aware of the need to maintain confidentiality of protected health information, especially in consideration of HIPAA, some doubts linger among lay people that their privacy will be assured.

Demand for lab testing still popular

The impact of at-home pregnancy test has not been significant in the context of clinical-laboratory testing. A demand for both urine and blood pregnancy testing exists in our hospital laboratory. For example, patients in the emergency department requiring procedures (e.g., X-rays) or medications completely unrelated to pregnancy are frequently tested to rule out pregnancy. The blood pregnancy test, in these situations, would be ordered particularly when a first-morning urine specimen cannot be obtained.

Patty Hopkins, MLS(ASCP)CM
Laboratory Director for the Pediatric Center, Thomasville, GA

DIY pregnancy tests popular with teens

I think most modern women prefer knowing the results immediately; using at-home urine pregnancy tests is easier and far less costly. Many women do not like having blood drawn, and this hCG test is an invasive procedure. I do believe the blood test for hCG is only used currently to perform a quantitative result for women who have miscarried or to check them for an abnormal pregnancy. At-home pregnancy urine tests are popular among teenagers who are becoming pregnant; it alleviates the risk of having parents find out. Most physician offices use the urine pregnancy test since it is a waived test and is reasonably accurate. The costs are minimal, results are immediate, and the test does not involve an invasive procedure.

Look to history

A urine-based pregnancy test was found in an ancient Egyptian document from 1350 BCE wherein a pregnant woman’s urine promoted growth of barley (male child) or wheat (female child) — or neither (no child). Scholars have speculated that elevated levels of estrogens in a pregnant woman’s urine may have promoted the growth of barley and wheat, whereas the urine of non-pregnant women and men did not. Reviewing historical records aids physicians and medical-lab scientists in inventing new, improved test methods. Interesting to note is that, even without technology or instrumentation, physicians in ancient times were able to diagnose today’s common health issues like diabetes and urinary-tract infections.

From 1590 to 2011 is long journey

In Greece’s heyday, physicians like Hippocrates only used sight and smell to diagnose health problems, along with observing symptoms and lifestyles of patients diagnosing them based on those findings. Observing urine — uroscopy — was their check for pus and blood in urine. The microscope, first invented in 1590, enabled early scientists to confirm that bacteria caused illnesses.

Director of Laboratory Services, Swedish American Health Systems, Rockford, IL

Use of hCG as a supplement

Often coupled with extreme calorie restriction (500 calories per day), injections of hCG are touted as a means of mobilizing fat stores to achieve rapid, easy weight loss. Proponents of this diet promise that it provides mobilization of abdominal fat and the ability to sculpt the body. “True” hCG is extracted from the urine of pregnant women or produced via recombinant DNA techniques, and does have recognized pharmacologic properties; however, weight loss has not been one of them. Since hCG injections must be prescribed by a licensed physician or imported from overseas pharmacies, some hCG diet proponents may encourage the use of hCG modified for oral dosage or homeopathic preparations (extremely dilute hCG in an alcohol suspension). hCG is a banned substance by both the National Football League and Major League Baseball because of its ability to restart natural testosterone production after steroid use.

Why home testing?

In-home urine pregnancy testing became available in the United States in late 1977. Early tests were based on the hemagglutination inhibition method, which — even in a laboratory setting — was fraught with potential for error. The ability to perform the test privately and to keep the results private may be one of the most powerful motivating forces for women. Social, moral, and economic forces are all considerations when a pregnancy occurs. If performed according to the package directions (most in-home tests now are virtually error-proof), a positive urine pregnancy test is fairly accurate. A negative test, especially in light of the potential for pregnancy, still needs to be verified by waiting an additional week and repeating, or by utilizing more sensitive laboratory methods. Despite the general reliability of the in-home test, most physicians will repeat the test to verify pregnancy before a treatment plan is established for a patient, so the need for in-lab testing really has not declined.

Lisa Ballou, MS, MLS(ASCP)DLMCM,
Laboratory Technical Services Manager,
Riverside Regional Medical Center, Newport News, VA

False-positive hCG test results

Although rare, there are false-positive hCG results due to interfering antibodies, often referred to by the general term “heterophile antibodies.” These antibodies often develop as a result of exposure to foreign animal proteins. They have the potential to interfere with two-site immunoassays by bridging the capture and detection antibodies in the absence of hCG. Most immunoassays contain non-specific blocker immunoglobulins to minimize the effect of the interfering antibodies. If test results do not match the clinical picture, patient serum can be pre-absorbed to remove heterophile antibodies prior to retesting.

Over-the-counter pregnancy tests

Millions of women elect to perform pregnancy testing in the privacy of their homes. The attractiveness of this relatively low-cost option is tied to the ease of use and the sensitivity of the test which allows for early detection. Clinical laboratories still perform testing requested by the OB-GYN community. Additionally, laboratories within healthcare centers routinely perform hCG testing to confirm the pregnancy status of any woman of child-bearing age who could be prescribed a medication or undergo a procedure that could be dangerous to her fetus.