Investigations

1st investigations to order

Test
Result
Test

ELISA should be ordered when HIV testing is indicated. False negatives may occur during window period immediately after infection before antibodies to HIV have occurred. A positive result should be confirmed with a Western blot or second ELISA. The window period can be reduced to 2 to 4 weeks by using fourth-generation tests and those that include IgM antibodies to HIV and/or HIV antigen (p24) assays.[63][68]

Result

positive

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Result
Test

Point of care test. Staff should be trained to do the rapid test. Should be ordered when HIV testing is indicated. False-negatives may occur during window period immediately after infection before antibodies to HIV have occurred. A positive result should be confirmed with a second rapid test.

Result

positive

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Result
Test

Most often used in surveillance. Most frequently sample buccal saliva. Both rapid and ELISA varieties are available.

Result

positive

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Result
Test

Expensive, so most often used as a confirmatory test following a positive ELISA or rapid test. During the window period result may be falsely negative or indeterminate.

Result

positive

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Result
Test

p24 protein is present during high viral replication and so is detectable in the blood during acute infection and again during late stages of infection. Its use, therefore, is as a supplementary test during the window period and is now part of newer fourth-generation assays indicated by the Centers for Disease Control and Prevention for routine HIV testing.[63]

Result

positive

Test
Result
Test

By HIV DNA PCR, qualitative proviral DNA in peripheral blood mononuclear cells can be used to make diagnosis of HIV especially during the window period. This is more costly than antibody-based diagnostic tests and is mainly used for HIV diagnosis in infants.

Result

positive

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Result
Test

Indicates immune status and assists in the staging process.

Result

CD4 count of >500 cells/microliter: patients are usually asymptomatic; CD4 count of <350 cells/microliter: implies substantial immune suppression; CD4 count <200 cells/microliter: defines AIDS and places the patient at high risk of most opportunistic infections

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Result
Test

An important test for establishing a baseline viral load before therapy and monitoring response to antiretroviral therapy. In developed countries, a baseline viral load followed by measurements at regular intervals is recommended, depending on the patient's response to therapy.[52] However, this is not common practice in resource-poor settings where testing for HIV RNA is less available.

Quantitative viral RNA in plasma is used to confirm acute HIV, including acute retroviral syndrome (i.e., symptomatic patients before the HIV antibody test is positive). Detectable levels of <1000 copies/mL may indicate a false-positive result and should be repeated in 1 month, along with antibody tests. However, if the result is well >1000 copies/mL, then the diagnosis is confirmed. Quantitative viral RNA is not recommended as a diagnostic test in other clinical scenarios because it can be falsely positive.

Result

recently infected people may attain levels in the millions of copies/mL; during control of infection, viral load may be controlled in the thousands or hundred of thousands; end stages of infection viral loads increase again into millions

Test
Result
Test

Genotypic testing is recommended at diagnosis to guide selection of initial antiretroviral therapy. Treatment should not be delayed while awaiting results, as the regimen can be modified once results are received.[52]

A Cochrane review found that drug resistance testing (genotypic or phenotypic) is likely to have little or no impact on mortality, progression to AIDS, or CD4 count. However, it may reduce the risk of virologic failure and viral load in patients who are experiencing treatment failure. It is unclear whether resistance testing provides any benefit for treatment-naive patients.[70]

Result

variable

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Result
Test

All women of childbearing potential should have a pregnancy test prior to starting antiretroviral therapy as some drugs are not recommended in pregnancy. Urine beta human chorionic gonadotropin (beta-hCG) is sufficient.

Result

positive in pregnant women

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Result
Test

Should be performed at baseline, before starting antiretroviral therapy, or if liver function is abnormal. Also recommended before starting direct-acting antiviral therapy for hepatitis C infection due to risk of hepatitis B reactivation.[52]

Result

surface antigen positive in hepatitis B-infected patients

Test
Result
Test

Hepatitis C testing (hepatitis C virus antibody or RNA) should be tested in all patients at baseline and every 12 months in at-risk patients.[52]

Result

antibody positive in hepatitis C-infected patients

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Result
Test

Nontreponemal antibodies will detect primary and early syphilis. Titer reduces with adequate treatment. Lack sensitivity in late stages of syphilis.

Result

positive in patient with syphilis infection

Test
Result
Test

Good screening for all stages after primary syphilis. Remains positive after treatment.

Follow-up tests are fluorescent treponemal antibody absorption test, rapid plasma reagin, or enzyme immunoassay.

Result

positive in patient with syphilis infection

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Result
Test

Follow-up test.

Result

positive in patient with syphilis infection

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Result
Test

Indicated to establish evidence of exposure to and infection with tuberculosis (TB). False-negatives may occur in anergic patients (advanced HIV).

Result

a reaction of more than 5 mm in a patient who has been screened for TB disease may require TB prophylaxis

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Result
Test

Requested before initiation of antiretroviral therapy and monitored while on therapy.

Result

may be normal or show anemia or thrombocytopenia

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Result
Test

Requested before initiation of antiretroviral therapy and monitored while on therapy.

Result

may be normal or deranged

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Result
Test

Requested before initiation of antiretroviral therapy and monitored while on therapy.

Result

may be normal or elevated in coexisting renal disease

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Result
Test

Requested before initiation of antiretroviral therapy and monitored while on therapy.

Result

may be normal or show proteinuria in renal disease or positive for leukocytes and nitrites in urinary tract infections

Investigations to consider

Test
Result
Test

Should be requested if there are symptoms or signs of tuberculosis (TB), P jirovecii pneumonia, or other pulmonary illness.

Result

Pneumocystis jirovecii pneumonia: interstitial to extensive alveolar shadowing; TB: many abnormalities possible including apical fibrosis/scarring, pleural effusion, hilar adenopathy, miliary pattern, lobar or patchy opacification; bacterial pneumonia: lobar or patchy opacification

Test
Result
Test

Requested before initiation of antiretroviral therapy and monitored while on therapy.

Result

may be normal; baseline abnormal LFTs may reflect chronic hepatitis B, chronic hepatitis C, or alcoholism

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Result
Test

Requested before initiation of antiretroviral therapy (ART) and monitored while on therapy.

Result

cholesterol levels may be low at diagnosis; ART may be associated with rising levels

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Result
Test

Requested before initiation of antiretroviral therapy (ART) and monitored while on therapy.

Result

may be elevated in patients on ART

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Result
Test

Should be performed in all patients. If the result is negative, the patient should be vaccinated against hepatitis A.

Result

may be negative or positive

Test
Result
Test

Should be performed at baseline in all HIV-infected individuals, particularly those with a CD4 count of <200 cells/microliter.

If the result is positive and the CD4 count is <50 cells/microliter, prophylactic therapy should be started.

Result

may be negative or positive

Test
Result
Test

Perform at baseline and every 3, 6, or 12 months depending on sexual activity risk.

Urine/urethral swab, rectal swab, and throat swab should be taken for culture for nucleic amplification test. If test is positive, the patient should be treated with appropriate antibiotics.

Result

may be negative or positive

Test
Result
Test

Should be ordered before initiation of antiretroviral therapy to assist with selecting the most suitable regimen. If positive, abacavir should be avoided.

Result

may be negative or positive

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