Internal Medicine Correlations and Clinical Scenarios (CCS) USMLE Step 3

CASE 10: Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Setting: office

CC: “Here for the results of my HIV test.”

VS: normal

HPI: A 34-year-old man comes to your office for a discussion of his HIV test, which he took when he had an episode of urethritis 1 week ago. He has been asymptomatic. You have just informed the patient that his test is positive.

PMHX:

Image Urethritis: finished treatment with ceftriaxone and azithromycin

Image Herpes simplex: 1 to 2 episodes a year

Medications: none

PE: normal

Initial Orders:

Image Lymphocyte subsets (CD4 count)

Image Polymerase chain reaction (PCR) HIV RNA viral load assay

Image Genotype of HIV virus

Image CBC, lipid panel

Image RPR

Image Purified protein derivative (PPD) skin test

Image Hepatitis B serology (surface antibody, core antibody, surface antigen)

Image Hepatitis C antibody

CCS and Step 3 examination, in general, very much want you to know the routine health maintenance and preventive medicine of diseases such as diabetes and HIV. It does not matter that the patient is asymptomatic with a normal physical examination. The tests listed here are needed. They are not extra or unnecessary. Students often ask, “Are you penalized for unnecessary tests?” The answer is: Absolutely you are! However, testing for latent tuberculosis (TB), hepatitis, and syphilis are not unnecessary in HIV.

Why get genotyping if there is no previous drug treatment?

a. All patients have some resistance.

b. Resistance to even one drug can be damaging at the start of therapy.

c. You are documenting the baseline. It has no effect on therapy.

Answer b. Resistance to even one drug can be damaging at the start of therapy.

If the patient is resistant to one of the medications you plan to start, it can be damaging to treatment. There is a <5% chance of resistance in a treatment-naïve person, but it is critical to be sure that your patient is sensitive to all three medications at the start of therapy.

The patient returns in a few days to discuss results. It is important to see the patient frequently at the beginning of therapy to form a bonded doctor-patient relationship that encourages adherence to medications.

Do not forget to take a thorough sexual history and to advise partner notification. Although you have the legal right to notify the partners yourself, Step 3 examination will always want you to encourage the patient to notify the partners themselves.

Reports:

Image Lymphocyte subsets (CD4 count): 335 cells/mm3

Image PCR HIV RNA viral load: 140,000 copies (< 20 undetectable)

Image Genotype of HIV virus: no resistance detected

Image CBC, Lipid panel: normal

Image RPR: Nonreactive

Image PPD skin test: no reaction

Image Hepatitis B serology (surface antibody, core antibody, surface antigen): negative

Image Hepatitis C antibody: positive

All patients with CD4 counts <500 cells/mm3 should be on antiretroviral therapy.

PPD >5 mm is positive in HIV.

Discuss the need to take antiretroviral therapy with the patient. Make sure he understand the need for essentially 100% adherence to medication to assure control of the virus. There is no point in starting antiretroviral medications to which the patient will not adhere.

Orders:

Image Emtricitabine

Image Tenofovir

Image Efavirenz

Image Hepatitis C RNA viral load

• Emtricitabine and tenofovir inhibit reverse transcriptase (Figure 10-9).

• Reverse transcriptase

• Converts RNA of HIV into DNA

• Prepares for entry into the HIV nucleus

Image

Figure 10-9. Replicative cycle of human immunodeficiency virus (HIV). The sites of action of the important antiviral drugs are indicated. (Modified and reproduced with permission from Ryan K, et al. Sherris Medical Microbiology, 3rd ed. New York: Mc-Graw Hill; 1994. Copyright 1994, McGraw-Hill.)

Protease Inhibitors

• Prevent packaging of HIV

• Prevent protein covering of RNA

• Stop infection of next HIV virus

Have the patient return in 1 week to discuss adherence to medications. Antiretroviral medication is a lifelong commitment. It is important not to just hand someone a prescription and ask the patient to show up in 3 months for testing.

Interval History: No adverse effects of medications.”

Adherence <95% = Resistance Developing

Reports:

Image Hepatitis C RNA viral load: 850,000 units/mL

Viral load changes first in response to therapy.

Half-life of HIV

• In CD4 cell: 1.2 days

• In plasma: 6 hours

Orders:

Image Interferon

Image Ribavirin

Image Boceprevir

Image Gastroenterology evaluation

Three Drugs for Hepatitis C

• Sustained viral response 70% to 80%

Have the patient return in 4 weeks.

Interval History: “No adverse effects of therapy.”

Orders:

Image PCR HIV RNA viral load assay

Image CD4 count

Image Hepatitis C RNA viral load

Report:

Image Both HIV and hepatitis C viral load are reduced by 90%

Image CD4: 425 cells/mm3

Treat the hepatitis C for 6 to 12 months depending on the genotype. If the HIV viral load rebounds up, recheck the genotype to see if there is resistance. Otherwise, just continue lifelong therapy.

On CCS, it can be difficult to tell how long to manage the case. Just keep moving the clock forward. Seeing “this case will end in 5 minutes of real time” can be jarring to some people. It does not mean you made a mistake.



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