A 37-year-old presents with fevers and a rash

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A case by Dr. Natalie Bavli

UT Southwestern Medical Center

Complete blood count (CBC) at time of admission:

What next test would be most useful?

a
MCH
b
RDW-SD
c
WBC differential
d
Anti-platelet antibodies
e
Blood alcohol level

 The following is the patient’s WBC differential:

Here is a crib sheet to keep handy:

Now let’s look at the patient’s CBC and on the following day:

True or false: the anemia that develops over one day in this case may be explained by profound suppression/reduction in erythropoiesis.

a
True
b
False
Even with complete shutoff of red cell production, assuming normal RBC survival, the Hb will fall by only 1% per day, much slower than in this case!

Now let’s look at the patient’s CBC and on the following day:

Let’s extend out the time CBC time series:

What is the significance of nucleated red blood cells (nRBCs) (more than one answer may apply)?

a
Underlying acute leukemia
b
Paroxysmal nocturnal hemoglobinuria
c
Stressed bone marrow (hemolysis, bleed)
d
Bone marrow infiltration or fibrosis

Below are examples of nucleated red cells:

We noted that the MCV increases over time. What is the likeliest explanation(s)?

a
Vitamin B12 deficiency
b
Liver disease
c
Reticulocytosis
This is one of the few ways that the MCV can change acutely (within days). Other causes listed take months for the MCV to increase.
d
Alcohol use
e
Hypothyroidism

Let’s look at the reticulocyte count (CT):

Is this patient’s reticulocyte response appropriate or inappropriately low?

a
Appropriate
b
Inappropriately low

Physical exam of the patient does not reveal any evidence of active bleeding, so you now suspect there may be hemolysis.

The following are the patient’s hemolytic markers:

These data are consistent with (more than one answer may apply):

a
Hemolysis
b
Liver disease
c
Thyroid disease
d
Renal disease

The following are the patient’s hemolytic markers:

Which data are NOT consistent with hemolysis?

a
Elevated LDH
b
Elevated direct bilirubin
c
Elevated ALT
d
Elevated ALK phos
e
Low haptoglobin

Hopefully you are wanting to see a peripheral smear at this point, but we are going to save that for later 😉

When working up a case of hemolytic anemia, what is the first blood test to order?

Note that the direct antiglobulin test (DAT) is at the first branch point in the diagnostic algorithm for hemolytic anemia, separating causes into immune and non-immune.

Here are the results of the patient’s DAT:

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