COVID-19 Diagnosis, Differential
Diagnosis, and Treatment.
Diagnosis of COVID-19,
largely has been accomplished,
by nucleic acid amplification testing or "NAAT,"
typically, by reverse transcriptase
polymerase chain reaction,
an (RT-PCR) assay.
Antigen testing can be performed,
it is certainly rapid, it can be
performed as a point of care test,
so, at the site of a clinic
or emergency department,
but it is less sensitive than NAAT.
Serology or antibody detection
of course will be adequate
for diagnosing prior infection
or infection at least three to four weeks prior
to the time of testing,
however, there is variable
sensitivity and specificity,
keeping in mind that the antibody, assay,
must be specific to a component
of the SARS-Coronavirus II
and not creating a false positive
result in reaction to something else.
Also important, in the diagnosis of COVID-19,
is, to exclude as best as
one is able other etiologies
or even coexisting processes such
as other respiratory infections,
congestive heart failure,
multi-organ failures, exacerbations
of underlying reactive airway disease
or asthma or even COPD, and anxiety.
There is, as you would
imagine an extensive overlap,
between the presentation and symptoms of COVID-19
and many other respiratory illnesses, such as,
influenza, rhinovirus or even other coronaviruses,
as the cause of the common cold,
pertussis, causing whooping cough
and even atypical pneumonia, caused
by such bacteria as mycoplasma
or even tuberculosis.
With that extensive overlap,
you can imagine an initial presentation,
is completely non-specific,
patients with COVID-19 and
other respiratory illnesses,
will start off with a flu-like illness,
they will likely have lymphopenia, especially,
if one is having an initial robust presentation,
with elevated white blood cells
and a neutrophil predominance,
so-called left shift, if
that response also includes,
bands or metamyelocytes.
However, lymphopenia, can be quite prominent
several days even several weeks into COVID-19
and maybe a suggestion that
the patient has COVID-19,
versus other respiratory illnesses.
Certainly, development of pneumonia can
be seen in all respiratory illnesses,
that's part of the name and including COVID-19
and all these can progress to severe disease,
also can have critical complications,
especially, if an initial,
viral respiratory disease
other than SARS-Coronavirus II,
develops a secondary bacterial pneumonia
as a complication.
So, whereas the initial
presentation is nonspecific,
One, can use a specific testing
which will help distinguish COVID-19,
from other respiratory illnesses.
So, in that patient with a
and in whom one suspects COVID-19,
one, can perform RT-PCR testing
or a quick antigen test,
followed by PCR confirmation
for SARS-Coronavirus II.
If the patient is sick enough
to require hospitalization
and potentially other interventions,
then a chest computed tomography or a CT scan,
may demonstrate bilateral ground glass opacities
and diffused pneumonia or even
unilateral patchy processes,
in patients with COVID-19, versus other findings
and other types of respiratory illnesses.
In kidneys, one can develop or one
can see elevated BUN and creatinine
or evidence of acute kidney injury,
again, this doesn't distinguish COVID-19,
from other infections or respiratory illnesses,
but it is more commonly seen in
patients earlier on in their COVID-19,
than you might anticipate in other illnesses.
Similarly, cardiac abnormalities,
keeping in mind that the virus does
have tropism for among other organs,
the heart, one can see elevated troponin,
so, evidence, of myocardial damage
or injury as well as an abnormal EKG,
so, showing a dysrhythmia
or even sometimes access deviation on the EKG.
Liver function abnormalities,
so elevated liver enzymes such as,
AST, ALT, GGT, lactite dehydrogenase,
the alpha-HBDH, all these can be
seen early on in acute COVID-19,
which is, on the way to becoming severe,
but again, keep in mind there is still an
overlap with other respiratory illnesses.
Well, for symptomatic patients
with mild to moderate COVID 19
and do not have any comorbid conditions
can generally be treated as lower risk.
This allows for telephone
or telemedicine evaluation of dyspnea,
oxygen saturation if available.
An overall clinical picture of the patient
based on the patient's responses,
they can be directed
to the emergency department
or scheduled for an in-person clinic visit
if their symptoms warrant
Usually the things that get them sent
to the emergency department
are severe dyspnea, low oxygen saturation
or more severe symptoms
like chest pain, stroke, or hypoxia.
with mild to moderate COVID
symptoms and are at risk of progression
to severe disease.
Early COVID specific antiviral treatment
is recommended within five days of onset.
One of the most commonly prescribed
treatments is paxlovid,
but monoclonal antibodies
can still be used in regions
where the infection is likely
to be a susceptible variant.
Plasma and remdesivir
can also be used in some circumstances,
and if there is a situation where
none of these treatments are available,
Molnupiravir can be used.
Of course, the ideal
management is evolving as the pandemic
continues and local protocols
may differ depending on the region.
One generality to remember
is that specific anti-virus
therapy will have more effective
given early in the course of infection
while immune modulating agents
have more efficacy at later disease stages.
In the hospital setting,
continues to play a very important role
in the most severe cases.
Other treatments, such as dexamethasone,
broad spectrum antivirals, anticoagulants
are also frequently used in treatment
algorithms based on the patient's
global clinical picture.
In most cases, the recommendation
is to continue a patient
on their chronic medications
such as ACE or ARB antihypertensives.
So, this is of course I guess
the scary part of the pandemic,
knowing that while 80% of
patients have mild disease,
there is still a 15% severe
and a 5% critical component,
who can develop very, very,
so, it is good to have ways to diagnose them early
and hopefully provide some sort of
intervention to prevent progression to,
that point were,
they require ventilation,
intubation and potentially ECMO.