Knowledge Check

True of false: the terms erythrocytosis and polycythemia are generally used interchangeably.

a
True
b
False

Red cell mass is rarely measured directly.

Hemoglobin (Hb) and hematocrit (Hct) are expressed as weight of Hb or volume of red cells per volume of blood. Therefore, Hb and Hct values can increase in one of two ways:

  1. The weight of Hb or the volume of red cells increase relative to the volume of plasma (increased numerator).
  2. The volume of plasma decreases relative to the weight of Hb or volume of red cells (decreased denominator).

Sort the causes (top) with the type of polycythemia/erythrocytosis (bottom):

Sleep apnea
Diarrhea
Diuretics
Polycythemia vera
Burns
Uterine fibroids
Cyanotic heart disease
Smoking
Relative polycythemia
Absolute polycythemia

What is the difference between primary and secondary polycythemia/erythrocytosis?

a
Primary refers to high clinical relevance
b
Primary refers to cases occurring in childhood
c
Primary refers to cases in which the increased production of red cells is autonomous to the red cell progenitors
d
Primary refers to cases in which the increased production of red cells is driven by a factor external to the bone marrow.

What is Gaisbock’s Syndrome?

(see next slide)

  • First described in 1905
  • AKA:
    • Gaisbock’s polycythemia
    • Pseudo-polycythemia
    • Polycythemia of stress
    • Stress erythrocytosis
    • Polycythemia hypertonica
  • Originally described as a syndrome of true polycythemia characterized by an elevation in hematocrit and presence of hypertension.
  • Now refers to a type of relative polycythemia associated with normal red cell mass and decreased plasma volume.
  • Risk factors include:
    • Male sex
    • Hypertension
    • Smoking
    • Diuretic therapy
    • Obesity
    • Emotional or physical stress
  • Of these, hypertension (particularly diastolic hypertension) appears to be the most significant contributor to the polycythemia of Gaisbock’s syndrome
The original description

Additional reading:

True or false: Gaisbock’s polycythemia can be thought of a chronic form of relative polycythemia, as distinct from transient causes such as as diarrhea, vomiting and diuretics.

a
True
b
False
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