35 Clinical Manifestations and Classification of Erythrocyte Disorders Flashcards
In an average person, the red cell mass must provide the total body tissues with approximately _________ of oxygen to support life
0.25 L/min
The oxygen-carrying capacity of normal blood is
1.34 mL/g of hemoglobin (approximately 0.2 L/L of normal blood)
Its actions include respiratory control, transcriptional regulation of glycolytic enzyme genes, angiogenesis, and energy metabolism
Hypoxia-Inducible Transcription Factors (HIFs)
The major regulator of EPO production
HIF-2
Two principal negative regulators of HIFs
- Von Hippel–Lindau tumor suppressor (VHL)
- Prolyl hydroxylase domain-containing proteins (PHD), PHD2 (encoded by EGLN1)
In hypoxia, energy is produced by less efficient glycolysis accomplished by upregulation of transcription of glycolytic enzyme genes and increased glucose transport, a process known as the
Pasteur effect
The Pasteur effect and its exception in the metabolism observed in malignant tissue, referred to as the
Warburg effect
“Hemoglobin’s oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide”
Bohr effect
In chronic anemia, increased oxygen tissue delivery is accomplished by increased amounts of _______________________
2,3-bisphosphoglycerate
In acute anemia, the major donor areas for redistribution of blood are the
Mesenteric and iliac beds
In chronic anemia in humans, the donor areas are the
Cutaneous tissue and the kidney
In an otherwise healthy person, a measurable increase in resting cardiac output does not occur until hemoglobin concentration is less than ________ g/L
Less than 70 g/L
TRUE OR FALSE
The rate of EPO synthesis is inversely and logarithmically related to hemoglobin concentration
TRUE
The rate of EPO synthesis is inversely and logarithmically related to hemoglobin concentration
Anemia can be classified, based on determination of the red cell mass
(1) relative
(2) absolute
Characterized by a normal total red cell mass in an increased plasma volume, resulting in a dilution anemia, a disturbance in plasma volume regulation
Relative anemia
All anemias should be divided into anemias caused by decreased production and anemias caused by increased destruction of red cells.
The differentiation is based largely on the _______
Reticulocyte count
Morphologic classification subdivides anemia into
- (1) macrocytic anemia
- (2) normocytic anemia
- (3) microcytic hypochromic anemia
TRUE OR FALSE
The viscosity of blood decrease logarithmically with an increase in hematocrit
FALSE
The viscosity of blood increases logarithmically with an increase in hematocrit
TRUE OR FALSE
Absolute erythrocytosis is not normovolemic but is accompanied by increased blood volume, which in turn enlarges the vascular bed and decreases peripheral resistance.
TRUE
Absolute erythrocytosis is not normovolemic but is accompanied by increased blood volume, which in turn enlarges the vascular bed and decreases peripheral resistance.
TRUE OR FALSE
The presence of secondary gout and splenomegaly are usually signs of erythrocytosis rather than myeloproliferative neoplasm.
FALSE
The presence of secondary gout and splenomegaly are usually signs of a myeloproliferative neoplasm rather than of erythrocytosis alone.
TRUE OR FALSE
EPO-driven erythrocytosis is generally associated with increased platelet production.
FALSE
EPO-driven erythrocytosis is generally not associated with increased platelet production.
Cyanosis can result from
40–50 g/L of deoxygenated hemoglobin
15 g/L of methemoglobin
5 g/L of sulfhemoglobin
TRUE OR FALSE
Hematocrit does not on its own increase thrombotic risk unless the somatic or germline mutations causing polycythemia and erythrocytosis, respectively, also promote thrombosis
TRUE
Hematocrit does not on its own increase thrombotic risk unless the somatic or germline mutations causing polycythemia and erythrocytosis, respectively, also promote thrombosis
TRUE OR FALSE
Erythrocytosis pose a risk in surgical patients.
FALSE
Erythrocytosis does not pose a risk in surgical patients.
TRUE OR FALSE
In polycythemia vera, however, it has been advocated that normalization of red cell mass should be accomplished before surgery, but firm data supporting this practice are lacking .
TRUE
In polycythemia vera, however, it has been advocated that normalization of red cell mass should be accomplished before surgery, but firm data supporting this practice are lacking .
Erythrocytosis, is a condition in which the hematocrit percentage is above the upper limits of normal: higher than ______ in men and ______ in women
51% in men
48% in women
Red cell mass is normal but the plasma volume is decreased
Relative erythrocytosis
Differentiation of absolute from relative erythrocytosis can be difficult at hematocrit levels lower than 60%.
Red cell mass is increased above normal
Absolute erythrocytosis
Differentiation of absolute from relative erythrocytosis can be difficult at hematocrit levels lower than 60%.
Primary Erythrocytosis and Polycythemia
Acquired somatic (polycythemia vera)
Inherited germline mutations (such as gain-of-function EPOR mutations expressed within hematopoietic progenitors)- Primary familial and congenital erythrocytosis/ polycythemia (PFCP)
Caused by augmentation of erythropoiesis by circulating stimulatory factors such as EPO that is hypoxia induced (eg, high altitude, lung disease), EPO-producing tumors, or cobalt and manganese toxicity
Secondary erythrocytosis
Caused by inherited mutations of the VHL gene, have elevated or inappropriately normal EPO levels in relation to elevated hematocrit
Chuvash erythrocytosis
Prone to develop thrombosis, have elevated pulmonary pressure, and have increased mortality independent of the increase in hematocrit
Gene mutation in:
Erythrocytosis from HIF2α
Erythrocytosis from PHD2
Erythrocytosis from HIF2α : EPAS1
Erythrocytosis from PHD2: EGLN1
