Laboratory diagnosis of human immunodeficiency virus infection.

HIV infection and AIDS will continue to grow as a major medical and social problem. The incidence of heterosexual transmission is rising, and it will become increasingly difficult for physicians and counselors to assess an individual's risk of infection. In coming years, physicians can expect to see patients who are infected, but whose risk may not be apparent, and who may not present with conditions immediately suggestive of their infection. The majority of these patients may not even suspect they are infected. Many of the tests currently available for diagnosing HIV infection are very good. They are both highly sensitive and highly specific and their predictive values are good when their limits are understood. But, as HIV infection expands to an ever larger number of women and children and as the ability to sharply define risk groups fades, demand for a broader range of tests that can reliably confirm infection and are easy to perform can only increase. We have attempted to describe some of the common serologic tests currently used to diagnose HIV infection and some of the limitations of these tests. We also have pointed out that criteria used by laboratories for interpreting tests such as the Western blot may not always be uniform, and physicians should know the criteria used by their reference laboratory and the quality control measures taken. We also have attempted to describe some of the tests available to detect the virus, its genes, or its gene products. PCR and other rapidly evolving gene amplification techniques hold great promise as highly sensitive and specific tests for the diagnosis/confirmation of HIV infection. As with the serologic tests, it is important for those who may use these tests to understand their value as well as their limitations.