Rosen & Barkin's 5-Minute Emergency Medicine Consult (565 page)

• Major criteria:
  
  • Hgb >18.5 g/dL in men, >16.5 g/dL in women
    
  • Presence of JAK2 mutation by polymerase chain reaction (PCR) – clinches the dx
    
  • Oxygen saturation >92% and no other cause for secondary erythrocytosis
    
• Minor criteria:
  
  • Low serum erythropoietin level
    
  • Bone marrow aspirate and biopsy revealing panhyperplasia
    
• Adjuncts to diagnosis:
  
  • Platelets >400,000/mm
    ³
    
  • ANC >10,000 (WBC >12,000/mm
    ³
    )
    
  • Splenomegaly on exam or by CT
    
  • Leukocyte alkaline phosphatase elevation
    
  • B
    ₁₂
    >900 pg/mL; unbound vitamin B
    ₁₂
    -binding capacity >2,200 pg/mL
    

DIAGNOSIS

• General:
  
  • Dyspnea
    
  • Weakness/fatigue
    
  • Excessive sweating
    
  • Epistaxis/gingival bleeding
    
  • Pruritus (40% of PV):
    
    • Generalized
      
    • Exacerbated by warm bath or shower
      
    • Excoriations common in PV
      
  • Gouty arthritis and tophi
    
• Neurologic (hyperviscosity):
  
  • Headache
    
  • Vertigo/dizziness/tinnitus
    
  • Lethargy/confusion
    
  • Paresthesias
    
  • Cerebrovascular accident/TIAs
    
• Visual (hyperviscosity):
  
  • Amaurosis fugax
    
  • Scotoma/blurred vision
    
  • Ophthalmic migraine
    
• Cardiovascular:
  
  • CHF
    
  • Angina/myocardial infarction
    
  • Deep vein thrombosis (DVT)
    
  • Hypertension
    
• Extremities:
  
  • Erythromelalgia:
    
    • Secondary to capillary sludging
      
    • Burning pain in the feet or hands
      
    • Warmth, erythema/cyanosis and puffiness of hand and feet
      
    • Acral paresthesias
      
    • Worse at night
      
    • Relief with cooling and aspirin
      
    • Pulses intact
      
  • Painful ulcers of fingers and toes (digital ischemia)
    
• GI (unique to PV):
  
  • Hepatomegaly/splenomegaly
    
    • Sudden spleen enlargement in known PV suggests development of myelofibrosis
      
  • Epigastric discomfort/early satiety
    
  • Peptic ulcer disease/GI bleed
    
  • Budd–Chiari syndrome (hepatic vein thrombosis): Ascites and peripheral edema
    

• Hypertension
  
• Conjunctival suffusion
  
• Fundus: Venous engorgement
  
• Ruddy complexion/plethora
  
• Erythema/rubor of hands, feet, nail beds
  
• Skin excoriations from severe pruritus
  
• Splenomegaly (75% in PV)
  
• Hepatomegaly (30% in PV)
  
• Thrombotic complications:
  
  • 2/3 arterial, 1/3 venous
    
  • Cumulative risk of 2–5% per year
    
  • TIAs, stroke, MI, digital infarcts
    
  • Unusual venous thrombosis:
    
    • Splenic or mesenteric veins
      
    • Hepatic vein and IVC clot with subsequent cirrhosis/ascites (Budd–Chiari syndrome)
      
    • Cerebral sinus thrombosis
      
  • DVT, PE
    
• Complications of hyperviscosity:
  
  • Lethargy/confusion
    
  • Headaches, dizziness, vision changes
    
  • Crackles/findings of CHF
    
• Hemorrhagic complications:
  
  • Ecchymosis
    
  • Epistaxis
    
  • Gingival bleeding
    

CBC with platelets

• 1st priority: Distinguish relative from true erythrocytosis:
  
  • Volume repletion IV or PO, then repeat CBC
    
• 2nd priority: Evaluate for secondary causes:
  
  • Pulse oximetry with pO
    ₂
    <92%
    
  • Carboxyhemoglobin level
    
  • Erythropoietin level (normal or elevated if secondary)
    
  • CXR, chest CT, pulmonary function tests
    
  • Sleep study
    
  • Hgb electrophoresis
    
• RBC mass:
  
  • Cr-51–labeled RBCs by nuclear medicine
    
  • Concomitant plasma volume with I-131–labeled albumin
    
  • Not necessary if Hgb >18.5 in men, or >16.5 in women
    
  • Red blood cell mass <35 mg/kg (males) or <31 mg/kg (females) is normal.
    
  • Decreased plasma volume with normal RBC mass verifies relative erythrocytosis.
    
  • Elevated RBC mass suggests PV or secondary polycythemia.
    
  • Falsely low if iron deficient or obese
    
• PV suspected if:
  
  • Hgb >18.5 g/dL (men), 16.5 g/dL (women)
    
  • Absolute neutrophil count >10,000
    
  • Platelet count >400,000
    
  • Pulse oximetry >92%
    
  • Low erythropoietin level – a major clue
    
  • Vitamin B
    ₁₂
    level elevated in 30% (unbound vitamin B
    ₁₂
    -binding capacity elevated in 75%)
    
  • Uric acid elevated in 40%
    
  • Leukocyte alkaline phosphatase elevated in 70%
    
  • PCR for JAK2 gene mutation diagnostic of PV (seen in 97%)
    

Abdominal US or CT can detect a splenomegaly

See Etiology.

TREATMENT

ABCs with emphasis on fluid resuscitation if no evidence of CHF

• Fluid resuscitation to achieve hemodilution:
  
  • Withhold if evidence of CHF
    
• Emergency phlebotomy of 250–500 mL of blood over 1–2 hr replacing with an equal amount of 0.9% normal saline (NS)
  
• Removal of 1,000–1,500 mL of blood over 24 hr with a goal of Hct <60 or relief of symptoms:
  
  • Keep Hct >45.
    
  • Replace with an equal amount of 0.9% NS.
    
• Phlebotomize the elderly and those with cardiovascular disease more slowly:
  
  • Every-other-day phlebotomy
    
• Emergent surgery with polycythemia:
  
  • Phlebotomize to Hct of 45 to avoid thrombotic complications postoperatively.
    
• Thrombocytosis therapy:
  
  • Administer aspirin if platelet count is 500,000–1,500,000/mm
    ³
    and there are no hemorrhagic complications.
    
• Treat pruritus with diphenhydramine.
  

• Phlebotomy: Maintain Hct at 45% for men and 42% for women.
  
• Aspirin 81 mg daily if thrombocytosis
  
• Interferon-α (normalizes CBC in 80%):
  
  • Especially helpful for refractory pruritus and painful splenomegaly
    
  • Suggested in symptomatic patients <60 yr
    
• Anagrelide:
  
  • Specific for thrombocytosis
    
  • No risk of leukemia, ideal for younger patients with postphlebotomy thrombocytosis
    
  • Effective alone and can decrease need for or frequency of chemotherapy
    
• Hydroxyurea:
  
  • Mainstay of therapy, especially for patients >60 yr, with frequent phlebotomy requirements, thrombotic episodes, or refractory thrombocytosis
    
• Aldylating agents: Busulfan:
  
  • Severe refractory disease in the elderly
    
  • High risk of leukemic transformation
    

Temporary remission during pregnancy, no treatment usually needed

• In the neonate, defined as a peripheral venous Hct >65%, Hgb >22 g/dL:
  
  • Sample must be obtained >6 hr post delivery.
    
  • Capillary Hgb and Hct are 10% higher than venous (always rely on venous)
    
  • 1–5% of neonates
    
  • Up to 50% of neonates with intrauterine growth retardation
    
• Etiology:
  
  • Maternal–fetal hypoxemia secondary to maternal heart or lung disease, diabetes, preeclampsia, hypertension, or smoking
    
  • Delayed clamping of the umbilical cord with increase cord transfusion
    
• Symptoms and signs (most asymptomatic):
  
  • Acrocyanosis/plethoric
    
  • Tachypnea/respiratory distress
    
  • Irritable, lethargic, jittery, poor feeding
    
• Hypoglycemia and hyperbilirubinemia common
  
• Treatment:
  
  • Observation and serial CBCs
    
  • 0.9 NS 100 mL/kg per day (symptomatic)
    
  • Partial exchange transfusion: Remove 20 mL/kg blood and infuse equal amount of saline (persistent or severe symptoms)
    
  • Dextrose solutions if hypoglycemia
    

Caution with speed of phlebotomy and fluid resuscitation as noted

FOLLOW-UP

• New diagnosis of polycythemia
  
• Hct >60% without symptoms
  
• Symptoms of hyperviscosity
  
• Unstable vital signs/significant comorbidities
  

• Previous diagnosis of polycythemia, Hct <60, and asymptomatic
  
• Stable vital signs
  

All patients should be referred to a hematologist or primary care physician.

• Criteria for phlebotomy in polycythemia secondary to hypoxemia is not clear. While phlebotomy will decrease viscosity, it may decrease oxygen-carrying capacity.
  
• It is critical to distinguish PV from secondary causes of erythrocytosis since PV carries a high risk of thrombotic complications.
  
• Pruritus with water contact and erythromelalgia (pain, paresthesia and rubor in hands/feet) are unique features of PV.