This chapter is from the book
This chapter is from the book
This chapter is from the book
Diagnoses
Diagnosis of immunological disorders is made by examination of the blood or body fluids. Testing includes antibody tests to measure the client’s antibody response to the presence of HIV. These tests are the Enzyme-Linked Immunosorbent Assay (ELISA) test and the Western Blot Analysis test. Initially the client is checked using the ELISA test. If this test is positive on two occasions, the Western Blot Analysis test is performed. The Western Blot Analysis test is considered to be the most diagnostic test. This laboratory test identifies HIV antibodies. The indirect immunofluorescence assay (IFA) is also used to confirm the diagnosis. The advantage of the IFA is that it is easily performed and gives a faster response. Another test is the radioimmunoprecipitation assay (RIPA), which detects the HIV protein rather than antibodies.
An oral mucosal transudate (OMT) test is an alternative to the standard blood test. A treated pad is placed in the client’s mouth and gently rubbed between the cheek and gum. The pad collects an oral fluid called oral mucosal transudate. This reveals whether the client has HIV antibodies present. The urine HIV antibody test uses the urine E1A (ELISA) and urine Western Blot technique to detect HIV antibodies. The Home Access and the Oracle test are quick tests for antigens.
The progression of the disease can be tracked by monitoring several tests, including
- p24 levels: This test tracks the amount of viral core protein (p24 antigen). The person with HIV who is asymptomatic will present with a low p24 level, whereas the person with advanced AIDS will have an elevated p24 level.
- Viral load: A client with a viral load of less than 400 is considered relatively free of circulating virus.
- Lymphocytes counts: This test is part of a complete blood count. Clients with AIDS are often leukopenic (a WBC below 3500 cells/mm3) and usually lymphopenic (less than 1500 lymphocytes/mm3).
- CD4/CD8 counts: The percentage and number of CD4+ (T4) and CD8+ (T8) count indicates the amount of suppressor cells as they compare to the helper cells. People with AIDS have a lower than normal number of CD4+ cells. The normal ratio of CD8+ cells is approximately 2:1. (The first letters indicate the number of helper cells [CD4], and the second letters indicate the number of suppressor cells [CD8].) The normal ratio is to have twice as many helper cells as suppressor cells, but in the client with HIV, the number of suppressor cells is twice as many as helper cells.
- Viral culture: This test measures the amount of reverse transcriptase (RT) activity over 28 days. The more RT, the more active the virus.
After making the initial diagnosis of HIV, the physician makes a determination of the clinical status of the client. The Centers for Disease Control (CDC) and Prevention has classified HIV infection by the CD4 count and the opportunistic diseases that the client has experienced. Table 12.1 describes the CDC’s clinical categories.
TABLE 12.1 CDC Classification of HIV Infection
Classification |
Description |
Clinical Category A (Asymptomatic) |
A1: CD4 + T-cell count greater than or equal to 500 cubic mm/liter A2: CD4 + T-cell count of 200–499 cubic mm/liter A3: CD4 + T-cell less than 200 cubic mm/liter Confirmed HIV; persistent lymphadenopathy; acute (primary) HIV infection with accompanying illness or history of acute infection |
Clinical Category B (Symptomatic) |
B1: CD4 + T-cell count greater than or equal to 500 cubic mm/liter B2: CD4 + T-cell count 200–499 cubic mm/liter B3: CD4 + T-cell count less than 200 cubic mm/liter All the signs found in clinical category A, plus the client might have bacillary angiomatosis; oral leukoplakia; candidiasis; cervical carci- noma; diarrhea for one month or more; herpes zoster; idiopathic thrombocytopenic purpura; listeriosis; pulmonary mycobacterium tuberculosis; nocardiosis, pelvic inflammatory disease; peripheral neuropathy |
Clinical Category C (Symptomatic) |
C1: CD4 + T-cell count greater than or equal to 500 cubic mm/liter C2: CD4 + T-cell count of 200–499 cubic mm/liter C3: CD4 + T-cell count less than 200 cubic mm/liter All the signs found in clinical categories A and B, plus the client might have candidiasis of bronchi; cervical cancer; coccidioidomy-cosis; cryptococcoses; cryptosporidiosis; cytomegalovirus; retinitis; encephalopathy; herpes; histoplasmosis; Kaposi’s sarcoma; mycobacterium; Pneumocystis carinii pneumonia; Salmonella septicemia; toxoplasmosis of the brain; wasting syndrome of HIV |