Page 35 - Journal of Special Operations Medicine - Fall 2016

5,000/μL, >5 schistocytes per high-power field (Figure Subsequent laboratory studies demonstrated negative
1), and a haptoglobin of 10mg/dL. Laboratory studies blood, stool, urine, and respiratory cultures, and were
also demonstrated acute kidney injury (creatinine level, negative for Shiga toxin. Although complement levels
1.8mg/dL), acute liver injury (aspartate transaminase were initially depressed, these were drawn in the set-
level, 1,194U/L; alanine transaminase level, 631U/L), ting of ongoing TPE. Repeated values after completion
and elevated creatine kinase level (26,000U/L). Initial of TPE showed normalized C3/C4 levels. ADAMTS13
prothrombin and activated partial thromboplastin times activity sent prior to TPE returned with a normal level
were slightly elevated (16.9 seconds and 42.6 seconds, of 52%. Further workup revealed normal complement
respectively); however, both values normalized within factors I and H, negative antineutrophil cytoplasmic an-
24 hours. The patient’s fibrinogen level was 224mg/dL, tibody, and negative paroxysmal nocturnal hemoglobin-
which increased to 258mg/dL at 24 hours. The D-dimer uria evaluation (CD55/59).
level was >20μg/mL.
With knowledge of normal ADAMTS13 activity, in ad-
Figure 1 Peripheral blood smear at admission. dition to gradual improvement in hemolysis, thrombo-
cytopenia, and lactate dehydrogenase levels, TPE was
discontinued after 6 days. The patient was observed
off TPE and steroids, with continued improvement in
platelet and hemoglobin levels, and hemolytic param-
eters over the following 5 days. He was discharged
on hospital day 11 with a hemoglobin level of 8g/dL,
platelet count of 200 × 10 /μL, and creatinine level of
3
1.1mg/dL. The patient’s hemoglobin level and platelet
counts would fully normalize 2.5 months after the ini-
tial presentation.

Discussion
This case demonstrates that not all instances of he-
molytic anemia and thrombocytopenia present with a
clear underlying etiology. TMA can be difficult to diag-
nose at initial presentation, but any time the diagnosis
is considered, treatment with TPE should be initiated.
Additionally, this case highlights that not all TMA is
due to ADAMTS13-deficient TTP or HUS, and a broad
diagnostic workup should be explored. In the absence
of ADAMTS13 deficiency, Shiga toxin, and drugs or
toxins known to cause TMA syndrome, the diagnoses
of atypical HUS (aHUS) or idiopathic TTP must be con-
sidered. Both of these syndromes may present with a
prodrome of nonbloody diarrheal illness and hemolytic
anemia, such as seen in this patient, but are differenti-
ated by laboratory analysis. The following discussion
will highlight these diagnoses, and discuss why this pa-
tient likely represents a case of atypical TMA syndrome
Note schistocytes (arrow) and relative absence of platelets.
of unclear etiology.

The patient was admitted to the intensive care unit, in- Diagnostic criteria for aHUS include the absence of Shiga
tubated for hypoxemic respiratory failure, and treated toxin on stool tests, ADAMTS13 activity >5%, and the
with therapeutic plasma exchange (TPE) and high-dose absence of a known precipitating cause of TMA syn-
steroids, because of the concern of possible TTP based drome, including medications, cancer, and pregnancy.
6
on hemolytic anemia, thrombocytopenia, and acute It should be noted that these criteria are not specific and
kidney injury. Disseminated intravascular coagulation may also be found in other primary TMA syndromes.
(DIC) was thought to be lower on the differential, be- Although this patient meets all these diagnostic crite-
cause of normalization of coagulation studies and slight ria, there are observations suggesting against aHUS: (1)
increase in fibrinogen at 24 hours, in addition to the relative to TTP, aHUS typically has less severe thrombo-
absence of sepsis or other identifiable triggers of DIC. cytopenia and more severe renal involvement, with up

Thrombotic Microangiopathy Syndrome: Case Report 17