Page 34 - Journal of Special Operations Medicine - Fall 2016
P. 34
Thrombotic Microangiopathy Syndrome
in a Basic Underwater Demolition/SEAL Student
Daniel Croom, MD; Heather Tracy, MD
ABSTRACT
Thrombotic microangiopathy (TMA) syndromes repre- and organ injury from pathologic small-vessel thrombo-
sent a spectrum of illnesses that share common clinical sis. At least nine primary TMA syndromes have been
and pathologic features of microangiopathic hemolytic described and classified based on common probable eti-
anemia, thrombocytopenia, and organ injury from ologies, diagnostic criteria, and treatments. 5
pathologic small-vessel thrombosis. At least nine pri-
mary TMA syndromes have been described and classi- The most recognized of these syndromes include TTP
fied based on common probable etiologies, diagnostic and HUS. Both are rare conditions; the estimated inci-
criteria, and treatments. The most recognized of the dence of idiopathic TTP is 3.7–11 cases per 1 million
TMA syndromes include thrombotic thrombocytopenic and of HUS is 2 per 100,000. TTP is an inherited or
6,7
purpura (TTP) and hemolytic-uremic syndrome (HUS). acquired ADAMTS13 deficiency resulting in small-vessel
Advanced laboratory techniques are required to distin- platelet-rich thrombi that cause thrombocytopenia, mi-
guish between these syndromes; however, all patients croangiopathic hemolysis, and end-organ damage. The
should initially be treated with plasma exchange for mortality rate associated with TTP was as high as 90%,
presumed ADAMTS13 deficiency-mediated TMA. The but TTP is now treated with plasma exchange, which
authors present a case of a TMA syndrome in a Navy has reduced the mortality rate to 10%. HUS most often
8
SEAL (Sea, Air, Land) candidate. occurs in the setting of an enteric infection with Shiga
toxin–producing Escherichia coli, most commonly strain
Keywords: syndrome, hemolytic-uremic; thrombotic throm- O157:H7. The Shiga toxin causes cell damage in addi-
bocytopenic purpura; microangiopathies, thrombotic; dis- tion to inducing proinflammatory and prothrombotic
seminated intravascular coagulation states leading to vWF secretion. The treatment is sup-
portive and may include dialysis for renal failure. 6
Other TMA syndromes include medication-induced,
Introduction
complement deficiencies, and atypical or idiopathic
In 1924, Moschowitz published the first description of causes. Advanced laboratory techniques are required
TTP in a 16-year-old girl who developed pallor, fever, to distinguish between the TMA syndromes; however,
hemiparesis, and thrombi, found on autopsy in arteri- all patients should initially be treated with plasma ex-
oles and capillaries of various organs. In 1955, Gasser change for presumed ADAMTS13 deficiency-mediated
1
et al. described a related disease, HUS, characterized by TMA because of the extremely high mortality rate with-
2
thrombocytopenia, hemolytic anemia, and renal failure. out treatment.
The pathophysiology of these diseases remained a mys-
tery until 1982, when unusually large multimers of von Case Report
Willebrand factor (vWF) were found in patients with A previously healthy, 21-year-old man presented with
chronic relapsing TTP. The formation of these multim- dyspnea, weakness, nonbloody diarrhea, and hemopty-
3
ers would later be linked to a deficiency in a vWF factor sis after discontinuing training on day 5 of “Hell Week”
cleaving protease named “a disintegrin and metallopro- in Basic Underwater Demolition/SEAL training. His ex-
teinase with a thrombospondin type 1 motif, member amination was notable for pallor, coarse breath sounds,
13” (ADAMTS13). 4 and pinpoint nonblanching erythematous lesions on
both lower extremities.
These diseases are now known as TMA syndromes, de-
fined by the shared clinical and pathologic features of On admission, he was found to have hemolytic ane-
microangiopathic hemolytic anemia, thrombocytopenia, mia, with a hemoglobin level of 6g/dL, platelet count of
16
