ERYTHROCYTES (Part 5) Flashcards
This is rarely done because of its inaccuracy and questionable necessity.
Manual RBC counts (Obsolete)
When automation is not available, what manual RBC tests are more accurate?
microhematocrit and hemoglobin concentration
Values that are ELEVATED in people living at a HIGHER ALTITUDE over what they would be at sea level?
RBC Count
Hemoglobin
Hematocrit
The difference in values in relation to the altitude?
1 g Hb/dL at 2 km altitude
2 g Hb/dL at 3 km altitude
Conventional unit for Children (8 to 13 y.o.):
4.00 to 5.40 x 10^6/μL
4.00 to 5.40 x 10^12/L
Conventional unit for Adult (male):
4.60 to 6.00 x 10^6/μL
4.60 to 6.00 x 10^12/L
Conventional unit for Adult (female):
4.00 to 5.40 x 10^6/μL
4.00 to 5.40 x 10^12/L
major glycolytic pathway
Embden-Meyerhof Pathway
Glucose penetrates the red blood cell with no energy expenditure via GLUT-1 (a transmembrane protein).
Embden-Meyerhof Pathway
Handles 90% of glucose utilization in the RBCs
Embden-Meyerhof Pathway
Non-oxidative, ANAEROBIC pathway that produces 2 MOLECULES of ATP
Embden-Meyerhof Pathway
ATP - used by the RBCs in the following ways:
- Maintenance of RBC shape & deformability
- Give energy for the active transport of cations
- Helps in modulating the amount o
2,3 - Bisphosphoglycerate (2, 3 BFG)
Old name of 2,3 - Bisphosphoglycerate (2, 3 BFG)?
2, 3 - Diphosphoglycerate (2, 3 DPG)
Old RBC becomes more ____________.
spherocytic
Most common enzyme deficiency of the EMP and is the most common form of HNSHA.
Pyruvate kinase (PK) deficiency
Possible PBS findings or PK deficiency include?
Acanthocytes Burr calls
What is the meaning of HNSHA?
Hereditary Nonspherocytic Hemolytic Anemia
Recommended screening test for PK deficiency
PK fluorescent spot test
A screening test for PK deficiency
Autohemolysis test
Pattern of autohemolysis associated with PK deficiency?
Autohemolysis is greatly increased and glucose has no effect (but ATP corrects the hemolysis) [TYPE II].
Confirmatory test for PK deficiency?
Quantitative PK assay
Three alternate pathways that branch from the glycolytic pathway?
- Hexose Monophosphate Shunt (Aerobic Glycolysis)
- Methemoglobin Reductase Pathway/Shunt (MRP) (MRS)
- Rapoport-Luebering Shunt
Other names for Hexose Monophosphate Shunt [HMS] (Aerobic Glycolysis)?
Pentose Phosphate Pathway or Phosphogluconate Pathway
aerobically converts glucose to pentose and produces NADPH (reduced)
HMS
What is the meaning of NADPH?
Nicotinamide adenine dinucleotide phosphate
Can also protect the HEME IRON but less effective than the MRP/MRS?
HMS
Prevents the denaturation of the GLOBIN by oxidation?
HMS
Functionally dependent on G6PD (important to HMS to operate normally)?
HMS
NADPH reduces to?
GLUTATHIONE (reduced glutathione reduces peroxides and guards proteins, lipids, and heme iron from oxidation)
Most common enzyme deficiency in the pentose phosphate pathway?
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
MOST COMMON RBC enzyme defect (prevalence of 5% of the global population, or approximately 400 million people worldwide)?
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Possible PBS findings of G6PD deficiency includes?
Heinz Bodies
Bite cells
Recommended screening test for G6PD deficiency?
G6PD fluorescent spot test
A screening test for G6PD deficiency
Autohemolysis test
Pattern of autohemolysis associated with G6PD deficiency?
Autohemolysis is slightly to moderately increased but is partially corrected by glucose. [TYPE I]
Confirmatory test for G6PD deficiency?
Quantitative G6PD assay
*Classification of G6PD Deficiency Variants by the WHO
Class I
Class II
Class III
Class IV
Class V
G6PD Enzyme Activity of CLASS I
SEVERELY deficient:
<1% activity or not detectable
Clinical Manifestations of CLASS I
- Chronic
- Rare
- HNSHA
- Severity is variable
Examples of Variants of CLASS I
G6PD-Serres
G6PD-Madrid
G6PD Enzyme Activity of CLASS II
SEVERELY deficient:
<10% activity
⭐️ Clinical Manifestations of CLASS II
- FAVA BEANS
- SOYA
- MENTHOL
- Severe
- Episodic acute hemolytic anemia associated with infections and Certain drugs
- NOT self-limited and may require transfusions during hemolytic episodes
Examples of Variants of CLASS II
G6PD-Mediterranean
G6PD-Chatham
⭐️ Only a small group of G6PD-deficient individuals demonstrate this,and most of these have the G6PD-Mediterranean variant?
FAVISM
(Unusual sensitivity to FAVA BEANS)
G6PD Enzyme Activity of CLASS III
MILD to MODERATE deficient:
10% to 60% activity
Clinical Manifestations of CLASS III
- Episodic
- Acute hemolytic anemia associated with infections and certain drugs
- Self-limited
Examples of Variants of CLASS III
G6PD- A-
G6PD-Canton
G6PD Enzyme Activity of CLASS IV
MILDLY deficient to NORMAL:
60% to 150% activity
Clinical Manifestations of CLASS IV
NONE
Examples of Variants of CLASS IV
G6PD-B (wildtype)
G6PD- A+ (may also manifest as CLASS III)
G6PD Enzyme Activity of CLASS V
INCREASED:
> 150% activity
Clinical Manifestations of CLASS V
NONE
Examples of Variants of CLASS V
Not reported
removal of a part of the RBC
PITTING
removal of the whole RBC
CULLING
⭐️ MUST BE AVOIDED in G6PD Deficiency Patients:
- SOYA
- MENTHOL
- NAPHTHALENE (mothballs) ⭐️
- Dapsone
- Methylthioninium chloride (methylene blue)
- Nitrofurantoin
- Phenazopyridine
- Primaquine
- Rasburicase
- Tolonium chloride (toluidine blue)
- Aniline dyes
- Fava beans
- Red wine
- Legumes (ex.: garbanzos, kadyos, munggo)
- Blueberry
- Ampalaya
- Cotrimoxazole
- Quinolones
- Sulfadiazine
- Some herbal supplements
Maintains iron in the HEME (Hb) in its reduced state (ferrous - Fe^2+)
Methemoglobin Reductase Pathway
Methemoglobin reductase AKA?
Cytochrome b5 reductase
⭐️ For the production of 2,3 - BPG
Rapoport-Luebering Shunt
In Rapoport-Luebering Shunt, 2,3 - BPG binds to ____________ and DECREASES the oxygen affinity of Hb.
Hemoglobin
(If attached to Hgb the oxygen will be released)
Two variables affecting the degree of association or dissociation between oxygen and hemoglobin:
- partial pressure of oxygen
- affinity of hemoglobin for oxygen
The AFFINITY of hemoglobin for oxygen is dependent on 5 factors:
- pH
- Partial pressure of carbon dioxide
- Concentration of 2,3-bisphosphoglycerate (2,3-BPG)
- Temperature
- Presence of other hemoglobin species that are nonfunctional
What is the curve produced when the 2 variables (partial pressure of oxygen and affinity of hemoglobin for oxygen) are PLOTTED ON A GRAPH (oxygen saturation of hemoglobin versus the partial pressure of oxygen)?
OXYGEN DISSOCIATION CURVE
A shift in the curve due to an alteration in pH (or hydrogen ion concentration); and the effect of hydrogen ions and CO2 on the affinity of hemoglobin for oxygen?
Bohr effect
Depicts the occurrence by which the binding of O2 to the hemoglobin promotes the release of CO2?
Haldane effect
SHIFT to the LEFT
↑pH
↓PCO2
↓2,3 - BPG
↓Temperature
INCREASED (↑) AFFINITY [how attached the O2 is to the Hgb]
SHIFT to the RIGHT
↓pH
↑PCO2
↑2,3 - BPG
↑Temperature
DECREASED (↓) AFFINITY