Lab med lecture 12

if they are symptomatic and treatment or infection control would help them (elderly/immunocompromised)

when should you test someone for COVID 19

viral test (PCR or antigen test)

what do you need for a diagnosis for COVID 19

PCR

highly sensitive and specific test for COVID 19 and lab based, so it takes longer to get back

antigen test

what are the rapid tests at home for COVID 19 called

false, they are less sensitive and specific

T/F:

antigen tests are highly sensitive/specific

they have false negatives early on so you must repeat a test in 48 hours if symptoms are still suspicious

what is a con about the antigen tests for covid

repeat an antigen test 48 hours later and do a PCR

if the patients antigen test comes back negative but still has symptoms consistent with COVID and was previously exposed what should you do

repeat antigen test 48 hours last and if negative repeat again 48 hours after that and PCR

if the patients antigen test comes back negative for COVID but was in recent exposure what should you do

She may still have COVID; her provider should order an NAAT

A 68-year-old woman with no known past medical history presents to the clinic with nausea, cough, and a fever X 1 day. She has just flown to Utah to visit her pregnant daughter-in-law. She took an at-home rapid antigen test for COVID this morning and it was negative. Which of the following is true?

A

what is the most common flu

A

what is the most severe flu

B

which flu is less common and less severe

C

which flu is an uncommon human pathogen

influenza

this illness is a respiratory illness distingushed by severity of systemic symptoms

NAAT

what is the test done for the flu that is highly sensitive and specific

NAAT

which test for flu can distinguish between A and B

Raid molecular test

which test for the flu is quick and highly sensitive and specific but cannot distinguish between A or B

direct antigen detection

which test for the flu is moderatly specific and sensitive and takes 1-4 hours for results

rapid antigen detection assay

which flu test has the most rapid results but is low sensitivity and specifity

The patient needs further testing prior to making changes in his management

A 73-year-old with a past medical history of Chronic Obstructive Pulmonary Disease (COPD) and Type II Diabetes Mellitus presents to the Emergency Department with 2 days of cough, fever, and shortness of breath. He states that his sister and her four children, who visited him 3 days ago had a cough when visiting and were diagnosed with Influenza B yesterday. The patient's chest x-ray shows bilateral patchy ground glass opacities. You elect to treat the patient for influenza empirically and start Oseltamivir (Tamiflu). A rapid influenza test comes back as below. Which of the following is true?

infectious mononucleosis

Illness caused by Epstein-Barr virus (EBV) which is characterized by a triad of fever, tonsillar pharyngitis, and lymphadenopathy

4 weeks

how long does it take until mono symptoms start to show

2-4 weeks

how long does mono last

>50% lymphocytes and >10% atypical lymphocytes

what must be present to diagnose infectious mononucleosis

EBV specific test

what must be confirmed before diagnosing infectious mononucleous

EBV specific antibodies

what is the gold standard test for diagnosing infectious mononucleosis

VCA antibodies

which antibodies are typically present at onset of symptoms

IgM

this antibody remains elevated for prolonged periods

IgG

this antibody can suggest acute or chronic infection

EBNA antibodies

if this test is positive it suggests mono in the past

EBNA antibodies (IgG only)

present 6-8 weeks after onset of symptoms. If present at onset of symptoms, effectively excludes acute EBV infection

VCA and EBNA

which two types of antibodies are within EBV specific

acute infection

what does EBV VCA IgM Positive suggest

EBNA

if EBV VCA IgM is Positive what must you also get to confirm it

confirms acute infection

EBNA negative

gets more complicated, depends on the timeline for sxs

EBNA positive

acute infection

early convalescence (3-6 weeks)

recovery (>6-8 weeks)

heterophile antibody testing

not recommended, reasonable alternative in young adult patients with fever and pharyngitis, in whom the pretest probability of IM is high

heterophile antibody testing

•If positive, supports diagnosis but false positives occur

•If negative, requires EBV-specific antibodies to confirm

acute mono

what is the diagnosis