The laboratory worker then dilutes a portion of the pooled sample by 10-fold. The other samples in the batch dilute each sample 10-fold. The technician pools 10 samples from 10 people. This method involves testing a pooled sample and a 10-fold dilution of the pool. Although this approach can detect the hook effect in undiluted samples, it is expensive because it requires additional labor and materials.Įxperts suggest that the sample pooling method can help prevent the hook effect at a much lower cost. Often, laboratory technicians will test undiluted and diluted samples to detect the hook effect. It is helpful for doctors to notify people, when relevant, of the possible inaccuracy of laboratory tests and the potential for false-negative or false-positive results.ĭoctors may find it challenging to identify the hook effect in laboratory tests. False-negative results from pregnancy tests can delay the confirmation of a pregnancy and, thus, prenatal care management. Blood tests for pregnancy may also come back negative, so the doctor may need to confirm the pregnancy with an ultrasound.Īs with other diagnostic tests, doctors should make a diagnosis based on a collection of data, including symptoms, clinical findings, medical images, and laboratory testing. Women who are experiencing symptoms of pregnancy but consistently getting negative test results from at-home urine pregnancy tests should consider speaking with a doctor. The hook effect is more common in the following situations:
In these situations, ultrasound tests may confirm the pregnancy. Some women may consistently get negative urine and blood pregnancy test results despite being pregnant. At high concentrations, the detection signal decreases.ĭoctors analyzing laboratory tests should keep the hook effect in mind because it can have important medical implications, including missed diagnoses and pregnancies. The test will produce a false-negative result because the antibodies are unable to detect the substance at higher-than-normal concentrations. When a sample contains too much of a substance, this can overwhelm the antibodies, resulting in them not attaching to it. The antibodies sandwich themselves around the substance, allowing for its detection. These assays use two antibodies to detect the substance in the sample. Laboratory technicians often use sandwich assays. Researchers suggest that it occurs in 0.2–2% of immunoassays, which are medical laboratory tests that use antibodies to detect specific substances or analytes. The following substances are subject to the hook effect:ĭoctors also call the hook effect the prozone or high dose hook effect. Instead of giving a positive result, the laboratory test becomes overwhelmed by the excess substance and provides a false-negative result. The hook effect occurs when blood, urine, or other samples contain too much of the substance that the specific pregnancy test is trying to detect. Share on Pinterest The hook effect may happen in a urine pregnancy test.
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