Clinical Manual > Testing and Assessment > Initial and Interim Labs

Initial and Interim Laboratory and Other Tests

July 2006; updated July 2007

Chapter Contents

Table 1. Initial Laboratory Evaluations for HIV-Infected Patients

Background

This chapter provides guidelines for monitoring patients with HIV infection.

Note that documentation of a confirmed HIV serologic test should be included in the chart.

O: Objective

Monitor patients with laboratory testing for HIV, hepatitis, sexually transmitted diseases, and other opportunistic infections (Table 1).

Table 1. Initial Laboratory Evaluations for HIV-Infected Patients

Test	Rationale	Result		Frequency and Comments
HIV Staging and Antiretroviral Therapy (ART) Monitoring
CD4 Count	For HIV staging and prognosis Guides initiation of ART Indicates risk of opportunistic illnesses and guides initiation of prophylaxis against opportunistic infections Used to monitor immune reconstitution during ART	Reported in cells/µL		Repeat every 3-4 months for patients not taking ART. Repeat every 2-4 months for patients taking ART. Repeat if results are inconsistent with the clinical picture or with previous trends. See chapter CD4 Monitoring and Viral Load Testing .
CD4 Count Percentage	Used in addition to the absolute CD4 count for monitoring trends; may be discrepant from absolute CD4 PCP prophylaxis is indicated for CD4% <14 regardless of absolute count (see below).	CD4 count	Expected CD4%	Usually obtained with absolute CD4 count
		>500	>29%
		200-500	14-28%
		<200	<14%
Quantitative Plasma HIV RNA (HIV Viral Load)	Estimates level of HIV replication Monitors effect of ART Diagnoses acute HIV infection (Not FDA approved for diagnosis of HIV, but has high sensitivity in setting of acute infection. Must be confirmed by positive HIV antibody test.)	Reported in copies/mL. In untreated patients, detectable (with rare exceptions) and measured to the upper limit of detection (usually >500,000 copies/mL). In patients taking ART, ideally suppressed to undetectable levels (usually <50 or ≤75 copies/mL).		Baseline values (2 tests). For patients on new or modified ART regimen: perform 2-8 weeks after initiation or change in ART. For patients on stable ART: perform every 3-4 months. For patients not taking ART: perform every 3-4 months; more frequently if CD4 count is low. Factors that may temporarily alter viral load: Immunizations Active infections
Drug Resistance Testing (Genotype, Phenotype)	To assess antiretroviral medications to which the patient's HIV virus is likely to be resistant	Genotype: detects specific mutations to ARV medications Phenotype: measures HIV viral replication in the presence of ARVs		Genotype (one time) is recommended in all ARV-naive patients. For greatest accuracy, should be done as early as possible in the course of HIV infection. Acute or primary infection: recommended Chronic infection and treatment naive: recommended before initiation of ART. Pregnancy: recommended before initiation of ART or in those with detectable HIV RNA during ART. Virologic failure: recommended (See chapter Resistance Testing for additional information.)
Complete Blood Count (CBC) with Differential and Platelets	Detects anemia, thrombocytopenia, leukopenia	Normal		Repeat every 3-6 months.
Complete Blood Count (CBC) with Differential and Platelets	Detects anemia, thrombocytopenia, leukopenia	Abnormal		Requires follow-up evaluation as indicated; may influence choice of ARVs. Repeat more frequently if the patient's results are abnormal or he/she is taking bone marrow suppressive drugs.
Chemistry Profile (Electrolytes, Creatinine, Blood Urea Nitrogen, Liver Transaminases)	Detects electrolyte abnormalities, renal insufficiency, hepatic enzyme elevations	Normal/abnormal		Repeat every 3-6 months, and as needed to monitor ART. May influence ARV selection. May be useful to monitor drug toxicities. Abnormalities should prompt evaluation of cause.
Lipid Profile (Total Cholesterol, LDL, HDL, Triglycerides) Glucose (preferably fasting)	Baseline before starting ART Monitoring during ART	Normal		Repeat annually or more frequently (every 3-6 months) based on initial results, ARV use, or risk of cardiovascular disease.
	Baseline before starting ART Monitoring during ART	Abnormal		For interventions, see chapter Dyslipidemia .
Test	Rationale	Result		Frequency and Comments
Hepatitis Screening
Hepatitis A Serology (HAV IgG)	Screen for immunity to hepatitis A; vaccinate those not immune	Negative		Offer hepatitis A vaccine if indicated. (See chapter Immunizations for HIV-Infected Adults and Adolescents .)
Hepatitis A Serology (HAV IgG)		Positive		Immune; no vaccine necessary
Hepatitis B Serology	Assess hepatitis B status
Hepatitis B Surface Antigen (HBsAg)	Indicates active hepatitis B	sAg negative		Consider vaccination if HBsAb negative (not immune).
Hepatitis B Surface Antigen (HBsAg)	Indicates active hepatitis B	sAg positive		Indicates chronic or acute hepatitis B infection; requires further evaluation (check HBV DNA)
Hepatitis B Core Antibody (Anti-HBc, IgG)	Indicates past exposure or ongoing infection	Anti-HBc negative		The patient most likely has not been infected with hepatitis B; consider vaccination if HBsAb negative and HBsAg negative.
Hepatitis B Core Antibody (Anti-HBc, IgG)	Indicates past exposure or ongoing infection	Anti-HBc positive		The patient most likely has been infected with hepatitis B; this test alone does not distinguish past exposure from active infection. In rare cases, may be falsely negative in some with chronic infection. If sAb negative and sAg negative, check HBV DNA to rule out active infection. If sAb is positive, patient is immune.
Hepatitis B Surface Antibody (Anti-HBs)	Indicates immunity status	Anti-HBs negative		The patient is not immune to hepatitis B; consider vaccination, unless patient has active hepatitis (sAg positive or HCV DNA positive).
Hepatitis B Surface Antibody (Anti-HBs)	Indicates immunity status	Anti-HBs positive		The patient is immune to hepatitis B either by previous infection or by immunization; may be negative in acute hepatitis B infection.
Hepatitis C Serology
Anti-HCV Antibody (HCV Ab)	Hepatitis C status	HCV negative		Patient is not infected with hepatitis C. Consider annual screening in high-risk patients.
Anti-HCV Antibody (HCV Ab)	Hepatitis C status	HCV positive		Patient has chronic hepatitis C infection or past infection with immunity; confirm positive results with HCV RNA.
Test	Rationale	Result		Frequency and Comments
Other Opportunistic Infection Screening Tests
Toxoplasma gondii IgG	Detects exposure; if positive, increased risk of developing CNS toxoplasmosis if CD4 count <100 cells/µL	Normal/negative		Repeat if patient becomes symptomatic or when CD4 count drops to ≤100 cells/µL.
Toxoplasma gondii IgG		Abnormal/positive		Note as baseline information. Start toxoplasmosis prophylaxis when CD4 count drops to ≤100 cells/µL.
PPD (tuberculin skin test) (if no history of TB or positive PPD)	Detects latent TB infection	Normal		Repeat every 6-12 months. Repeat if CD4 count was <200 cells/µL on initial test but increases to >200 cells/µL.
	Detects latent TB infection	Abnormal (induration ≥5 mm)		Evaluate for active TB. (See chapter Latent Tuberculosis .)
Chest X-Ray (if pulmonary symptoms are present or positive PPD)	Detects latent or active diseases	Normal		Repeat as indicated for pulmonary symptoms or positive PPD.
	Detects latent or active diseases	Abnormal		Evaluate for TB, PCP, or other pathology.
Papanicolaou Smear (cervical for women; anal for women and men)	Detects abnormal cell changes, dysplasia	Normal		Repeat in 6 months; then annually if negative on 2 smears and no ongoing risk factors.
	Detects abnormal cell changes, dysplasia	Abnormal		Perform workup, treat (see chapters Cervical Dysplasia and Anal Dysplasia ) and follow up more frequently as indicated by condition.
Test	Rationale	Result		Frequency and Comments
STD Testing: Identify sexually transmitted infections in any patient at risk.
Venereal Disease Research Laboratory (VDRL); or Rapid Plasma Reagin (RPR)	Syphilis screening	Negative titer		Repeat every 3-12 months, depending on risk factors.
	Syphilis screening	Positive titer: confirm with treponemal test		Treat patient; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex. Perform serial testing if monitoring active disease. (See chapter Syphilis .)
Women
Gonorrhea, Chlamydia, and Trichomoniasis Testing	STD screening in sexually active women at risk	Negative		Counsel about safer sex and avoiding STDs. Repeat every 6-12 months; more frequently if at high risk.
Gonorrhea, Chlamydia, and Trichomoniasis Testing	STD screening in sexually active women at risk	Positive		Treat patient; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex.
Gonorrhea and Chlamydia Testing, Rectal	STD screening in sexually active women at risk STD screening in sexually active women who have receptive anal sex	Negative		Counsel about safer sex and avoiding STDs. Repeat every 6-12 months; more frequently if at high risk.
Gonorrhea and Chlamydia Testing, Rectal		Positive		Treat patient; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex.
Men
Gonorrhea and Chlamydia Testing, Urethral	STD screening in sexually active men who are at risk, especially men who have sex with men (MSM)	Negative		Retest every 3-6 months in patients with risk factors.
Gonorrhea and Chlamydia Testing, Urethral		Positive		Treat; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex.
Gonorrhea and Chlamydia Testing, Pharyngeal	STD screening in sexually active men who are at risk, especially MSM who have oral-genital contact	Negative		Retest every 3-6 months in patients with risk factors.
Gonorrhea and Chlamydia Testing, Pharyngeal		Positive		Treat; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex.
Gonorrhea and Chlamydia Testing, Rectal	STD screening in sexually active men who are at risk, especially MSM who have receptive anal sex	Negative		Retest every 3-6 months in patients with risk factors.
Gonorrhea and Chlamydia Testing, Rectal		Positive		Treat; refer partner(s) of previous 60 days for evaluation and treatment; counsel about safer sex.
Test	Rationale	Result		Frequency and Comments
Consider/Optional
G6PD Level	Prevent hemolytic reactions by screening susceptible men of African, Mediterranean, Asian, Sephardic Jewish descent Some would recommend screening all patients	Normal range		No intervention is necessary beyond documentation
G6PD Level		Abnormal range		Avoid oxidant drugs such as dapsone, primaquine, and sulfonamides, if possible.
Cytomegalovirus (CMV) Antibody (anti-CMV IgG) for those at low risk of CMV, especially those who are not MSM or injection drug users	Detects exposure; may reveal future disease risk	Negative		Avoid exposure by practicing safer sex. If blood transfusion is required, use CMV-negative or leukocyte-reduced blood.
	Detects exposure; may reveal future disease risk	Positive		Be aware of disease risk in advanced HIV infection, when CD4 count <50 cells/µL.
Prostate Specific Antigen (PSA)	Prostate cancer screen (African American men over 45; other men over 50 with >10-year life expectancy)	Normal		Repeat annually.
Prostate Specific Antigen (PSA)		Abnormal		Refer to urology specialist for evaluation.
Urinanalysis (UA)	Detects proteinuria or pyuria	Normal		Repeat annually.
Urinanalysis (UA)	Detects proteinuria or pyuria	Abnormal		Rule out HIV-associated nephropathy and other causes of nephropathy.
Dilated Retinal Examination	Detects CMV, ophthalmic toxoplasmosis, or HIV retinopathy	Normal		CD4 count >100 cells/µL: repeat annually. CD4 count <50 cells/µL or symptoms of retinal changes: repeat every 6 months.
Dilated Retinal Examination	Detects CMV, ophthalmic toxoplasmosis, or HIV retinopathy	Abnormal		Follow up immediately with ophthalmologist

Patient Education

Discuss safer sex (review specifics appropriate to the patient's sexual practices and infections) to prevent the patient's exposure to herpes, hepatitis B, hepatitis C, and other sexually transmitted diseases, and to prevent the patient from exposing others to HIV or other pathogens. (See chapters Preventing Transmission/Prevention with Positives and Preventing Exposure to Opportunistic and Other Infections .)
If toxoplasma IgG test result is negative, see chapter Preventing Exposure to Opportunistic and Other Infections .
If cytomegalovirus (CMV) test result is negative, counsel the patient that CMV is shed in semen, vaginal and cervical secretions, saliva, and urine of infected people. Latex condoms will help reduce risk. For women considering childbearing, CMV should be avoided assiduously to prevent severe disease and even death of the neonate. (See chapter Preventing Exposure to Opportunistic and Other Infections .)
For people who are hepatitis C negative and still use injection drugs, offer referral to a drug treatment program. (See chapters Preventing Transmission/Prevention with Positives and Preventing Exposure to Opportunistic and Other Infections .)

References

Aberg, Gallant, et al. Primary Care Guidelines for the Management of Persons Infected with Human Immunodeficiency Virus: Recommendations of the HIV Medicine Association of the Infectious Diseases Society of America . Clin Infect Dis 2004 Sep 1;39(5):609-29. Available online at www.journals.uchicago.edu/CID/.

Bartlett JG, Cheever L. A Guide to Primary Care of People with HIV/AIDS , 2004 Edition . Rockville, MD: Department of Health and Human Services, HIV/AIDS Bureau. 2004. Available online at hab.hrsa.gov/tools/primarycareguide/.

Bartlett JG, Gallant JE. 2005-2006 Medical Management of HIV Infection . Baltimore: Johns Hopkins University Division of Infectious Diseases; 2005. Available online at hopkins-aids.edu/mmhiv/order.html.

U.S. Public Health Service, Infectious Diseases Society of America. 2002 Guidelines for preventing opportunistic infections among HIV-infected persons--2002 . MMWR Recomm Rep. 2002 Jun 14;51(RR08);1-46. Available online at aidsinfo.nih.gov/Guidelines/. Accessed May 19, 2006.

U.S. Department of Health and Human Services. Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents . October 10, 2006. Available online at aidsinfo.nih.gov/Guidelines/GuidelineDetail.aspx?GuidelineID=7. Accessed July 3, 2007.

Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines 2006 . MMWR 2006;55(No. RR-11):1-100.

Feinberg J, Maenza J. Primary Medical Care. In: Anderson JR, ed. A Guide to the Clinical Care of Women with HIV . Rockville, MD: Health Services and Resources Administration; 2001:354-359. Available online at hab.hrsa.gov/publications/womencare05/.

Hecht F, Soloway B. Laboratory Tests for Monitoring HIV Infection. In: HIV Infection: A Primary Care Approach, Revised Edition. Waltham, MA: Massachusetts Medical Society; 1993;17.

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