Page 18 - JSOM Winter 2022

TABLE 1 Complete Blood Count Value Trends
Upper Limit Reference 25 Aug 20 13 Oct 20 02 Nov 20 02 Feb 21 13 May 21
RBC 5.50 × 10 /μL 5.44 5.35 5.61 5.81 5.66
6
Hgb 16.6g/dL 15.5 13.9 14.6 14.8 13.9
Hct 48.4% 47 43.2 45 45.9 45.2
WBC 9.76 × 10 /μL 8.2 6.7 6.4 7.7 7.9
3
PLT 339 × 10 /μL 465 451 459 434 434
3

FIGURE 1 A unit of whole
blood is drawn from the patient
utilizing the blood collection bag
from a whole blood transfusion FIGURE 2 A unit of whole
kit. Fill estimation was blood drawn from the patient.
performed via a 6.5-inch piece
of paracord wrapped across the
waist of the collection bag.

levels of circulating blood cells, namely RBCs (erythrocytosis), of the blood and increased potential for thrombus forma-
WBCs (leukocytosis), and platelets (thrombocytosis). Tradi- tion. 3,6,10 Increased viscosity creates stress on cardiac muscle to
2–4
tionally, World Health Organization (WHO) guidelines spec- maintain adequate cardiac output, and when combined with
ify diagnostic thresholds for hemoglobin/hematocrit levels of thrombocytosis, produces an elevated risk for severe complica-
2,4
16.5g/dL/49% in males and 16g/dL/48% in females. While tions, including stroke, myocardial infarction, and pulmonary
some recommend testing for genetic alterations that cause this embolism. 3,6,9,10 Thrombotic events account for up to 45% of
disease, specifically the JAK2 mutation, these are generally ac- all deaths in PV patients. 3,5,11 Notably, blood clots occur in ap-
quired through bone marrow biopsy, with much communal proximately 30% of patients before PV is diagnosed. 3
disagreement for its necessity. Additionally, there are nu-
2–5
merous cases diagnosed in the scientific literature without this PV management centers on regulating intravascular mass by
2–5
finding. The estimated incidence of PV is approximately 2.8 decreasing the volume of circulating component levels, thus
per 100,000 in men and 1.3 per 100,000 in women, although alleviating symptoms and preventing complications, chiefly
frequency increases seven-fold for populations over 35 years thrombosis. Among these, adequate hydration is central to
old. Until 2020, there was no direct regulatory guidance lim- prevent excessive viscosity, made paramount by exertion and
3,6
9
iting the military enlistment or retention for those with PV, climates in many operational environments. Medical ther-
which may partially explain why there is no significant Ameri- apy primarily involves anticoagulation through daily admin-
can military epidemiological data on this condition. 7,8 istration of aspirin 81mg. Other medication options include
5
the use of cytoreductive and immunosuppressive therapies.
Initial symptoms of PV are often vague and nonspecific, in- However, these create a number of concerns, both within and
cluding headache, fatigue, chest pain, dizziness, paresthesias, outside of military populations. Aside from the increased sus-
and arthralgias, which often enable it to progress for years un- ceptibility to infection posed by immunosuppressive therapies,
diagnosed. As polycythemia progresses, patients may exhibit many of these therapies mandate referral to a PEB per Army
3,5
more severe symptoms, with the addition of pruritus, which in regulations and possible medical discharge from military ser-
7
5
textbook cases increases in warm conditions like hot showers. vice. Their use is therefore generally relegated to second-line
Splenomegaly may also be an additional late finding of con- therapeutic considerations given these concerns.
cern. Diagnosis should not be made in austere environments,
but rather elevated CBC findings on iSTAT or other point of The mainstay of treatment for PV consists of therapeutic phle-
care devices should prompt specialty consultation for further botomy, drawing 1 unit of WB at regular intervals to remove
considerations and management. In patients with and without circulating components. The intravascular space initially
5
diagnosed PV, local providers should always consider hemo- backfills with leeched soft tissue fluid and plasma, furthering
concentration from dehydration or other hypovolemia as a hemodilution and decreasing blood viscosity. Initial phlebot-
possible source of elevated laboratory findings and correlate omy should be scheduled monthly and monitored with post-
with serum creatinine levels to see if this may be the case. 9 draw laboratory evaluation at 2- and 4-week intervals to check
for patient response and verify treatment efficacy. Phlebotomy
The high risk of morbidity and mortality from uncontrolled PV may be decreased in frequency depending on patient response.
necessitates proactive monitoring by both patients and provid-
ers. Poorly managed PV creates a multitude of cardiovascular A single unit of WB consists of approximately 585g or
problems, largely from increased intravascular mass with the 450mL. 1,12 Although initial research found poor accuracy by
proliferation of RBCs and platelets, resulting in hyperviscosity medics to estimate WB collection bag volumes to reasonably

16 | JSOM Volume 22, Edition 4 / Winter 2022