Hemoglobin Flashcards
Hemoglobin reference range for children (8 to 13 y.o.) in conventional units,
12 to 15 g/dL
Hemoglobin reference range for children (8 to 13 y.o.) in S.I. units,
120 to 150 g/L
Hemoglobin reference range for adult males in conventional units,
14 to 18 g/dL
Hemoglobin reference range for adult males in S.I. units,
140 to 180 g/L
Hemoglobin reference range for adult females in conventional units,
12 to 15 g/dL
Hemoglobin reference range for adult females in S.I. units,
120 to 150 g/L
Main component of red blood cells, comprising 95% of cytoplasmic content,
Hemoglobin
Another name for hemoglobin,
Respiratory pigment
Concentration of hemoglobin within RBCs,
Approximately 34 g/dL
Molecular weight of hemoglobin,
Approximately 64,000 Daltons
Scientist who identified hemoglobin as a respiratory protein,
Felix Seyler (1862)
Percentage of hemoglobin produced before the RBC nucleus is extruded,
0.65
Percentage of hemoglobin synthesized in early reticulocytes,
0.35
Most common complex organic molecule in vertebrates,
Hemoglobin
Volume of O₂ carried by 1 gram of hemoglobin,
1.34 mL
Amount of iron carried by 1 gram of hemoglobin,
3.47 mg
Components of a complete adult hemoglobin molecule,
1) Globin (protein component) 2) Four protoporphyrin IX molecules 3) Four iron atoms in the ferrous form (Fe+2) 4) One 2,3-BPG molecule
Number of amino acids in alpha globin chain,
141
Number of amino acids in beta globin chain,
146
Number of amino acids in delta globin chain,
146
Number of amino acids in gamma A globin chain,
146 (position 136: alanine)
Number of amino acids in gamma G globin chain,
146 (position 136: glycine)
Number of amino acids in epsilon globin chain,
146
Number of amino acids in zeta globin chain,
141
Function of 2,3-BPG in hemoglobin,
Delivery of oxygen to tissues
Function of hemoglobin in relation to CO2,
Carries waste product CO2 away from the lungs
Function of hemoglobin in relation to nitric oxide (NO),
Binding, inactivation, and transport of NO
Amino acid sequence of the polypeptide chains structure,
Primary structure of hemoglobin
Chain arrangements in helices and non-helices,
Secondary structure of hemoglobin
Arrangement of the helices into a pretzel-like configuration or formation,
Tertiary structure of hemoglobin
Complete hemoglobin molecule: spherical, four heme groups attached to four polypeptide chains, carrying up to four molecules of oxygen,
Quaternary (tetramer) structure of hemoglobin
Reference method for hemoglobin determination,
Cyanmethemoglobin (HiCN) Method
Key reagents in Drabkin’s reagent,
Potassium ferricyanide (K3Fe(CN)6), Potassium cyanide (KCN)
Measurement wavelength for HiCN,
540 nm (spectrophotometer)
Time for full conversion of hemoglobin to cyanmethemoglobin,
10 minutes at room temperature
Types of hemoglobin measured by HiCN method,
All types of Hb except sulfhemoglobin
Reaction in the cyanmethemoglobin method,
Hemoglobin (Fe2+) + K3Fe(CN)6 → methemoglobin (Fe3+) + KCN → cyanmethemoglobin
Correction for high WBC count (> 20 x 10^9),
Centrifuge reagent-sample solution, then measure the supernatant
Correction for high platelet count (> 700 x 10^9),
Use lipemic plasma solution
Correction for lipemia,
Add 0.01 mL of patient’s plasma to 5 mL of cyanmethemoglobin reagent and use this as the reagent blank
Correction for Hb S and Hb C cells,
Dilute 1:2 with distilled water and multiply the results by 2
Correction for abnormal globulins (e.g., plasma cell myeloma, Waldenstrom macroglobulinemia),
Add 0.1 gram of potassium carbonate to cyanmethemoglobin reagent
Modification to cyanmethemoglobin reagent to prevent abnormal globulin precipitation,
Commercially available cyanmethemoglobin reagent contains KH2PO4 salt, preventing this issue
Cyanmethemoglobin reagent storage sensitive to light,
Store in a brown bottle or dark place
Alternative technique for hemoglobin measurement in automated instruments without producing toxic wastes,
Uses sodium lauryl sulfate (SLS) to transform hemoglobin to SLS-methemoglobin
Example of handheld system for hemoglobin measurement,
HemoCue
HemoCue hemoglobin measurement method,
Converts hemoglobin to azidemethemoglobin and reads photometrically at two wavelengths (570 nm and 880 nm)
Electrophoresis definition,
Movement of charged particles in an electric field
Primary screening procedure to detect variant hemoglobins,
Cellulose Acetate (pH 8.4-8.6)
Charge of hemoglobin in alkaline buffer (pH 8.4-8.6),
Negatively charged
Direction of hemoglobin migration in electrophoresis,
Toward the anode (+)
Fastest hemoglobin in cellulose acetate electrophoresis,
Hgb A/A1
Fast hemoglobins (abnormal/rarely found),
Bart Hb, HbH, HbI
Slowest hemoglobins in cellulose acetate electrophoresis,
Hgb C, A2, E, C (harlem), Hb O (arab)
Migration pattern of Hb S, Hb D, and Hb G in cellulose acetate electrophoresis,
Same area
Point of application in electrophoresis,
Cathode
Purpose of Citrate Agar (pH 6.0 to 6.2) electrophoresis,
Confirm variant hemoglobins and differentiate Hb S from D and G, and Hb C from E, OArab, CHarlem
Complementary procedure to cellulose acetate Hb electrophoresis,
Citrate Agar
Hemoglobin synthesis: Heme synthesis,
Occurs in mitochondria of metabolically active cells
Heme composition,
Ferroprotoporphyrin IX, a porphyrin pigment
Site of heme synthesis,
Mitochondrion
Heme biosynthesis location,
Prominent in bone marrow and liver
Major heme-forming tissue,
Erythroid marrow (85% of daily heme requirement)
Key enzyme in heme synthesis,
Ferrochelatase (Heme synthetase)
Function of Ferrochelatase,
Inserts Fe 2+ into the protoporphyrin IX ring
First step in heme biosynthesis,
condensation of succinyl-CoA and glycine by ALAS to generate ALA
Globin synthesis site
Ribosomes in the normoblast cytoplasm
Chromosome for Alpha and Zeta globins
Chromosome 16
Chromosome for Beta, Delta, Gamma, and Epsilon globins
Chromosome 11
Embryonic hemoglobins
Portland, Gower I, Gower II
Embryonic hemoglobin (Portland) Molecular structure:
2 zeta, 2 gamma
Embryonic hemoglobin (Gower I) Molecular structure:
2 zeta, 2 epsilon
Embryonic hemoglobin (Gower II) Molecular structure:
2 alpha, 2 epsilon
Predominant in fetus and newborns
Hgb F
Hgb F Proportion in newborns
0.8
Hgb A1 Proportion in newborns
0.2
Hgb A2 Proportion in newborns
<0.5%
Hgb F Proportion in adults
<1%
Hgb A1 Proportion in adults
0.97
Hgb A2 Proportion in adults
0.025
Hgb F Structure
2 alpha, 2 gamma
Hgb A1 Structure
2 alpha, 2 beta
Hgb A2 Structure
2 alpha, 2 delta
Oxyhemoglobin
Hb with Fe2+ and oxygen, found in arterial blood, bright red color
Oxyhemoglobin function
Transports oxygen from lungs to tissues
Oxyhemoglobin conformation
R state (relaxed) when oxygenated
Deoxygenated hemoglobin
Hb with Fe2+, not bound to oxygen, found in venous blood, dark red color
Deoxygenated hemoglobin function
Transports carbon dioxide from tissues to lungs
Deoxygenated hemoglobin conformation
T state (tense) when deoxygenated
Carboxyhemoglobin
Hb with Fe2+ bound to carbon monoxide (CO)
Carboxyhemoglobin affinity
CO has 240x greater affinity for Hb than oxygen
Carboxyhemoglobin gas properties
Colorless, odorless, tasteless gas
Carboxyhemoglobin poisoning symptoms
Cherry red color in blood and skin
Main cause of carbon monoxide poisoning
Automobile exhaust is the #1 cause of CO exposure
Methemoglobin (Hi)
Hb with Fe3+, not bound to oxygen
Methemoglobin blood color
Chocolate brown color in blood
Methemoglobin formation
Occurs due to oxidation of Fe2+ to Fe3+
Methemoglobin health impact
Prevents oxygen binding, leading to hypoxia
Sulfhemoglobin (SHb)
Mixture of oxidized and partially denatured Hb forms
Sulfhemoglobin causes
Prolonged constipation, enterogenous cyanosis, bacteremia, caused by C. perfringens
Sulfhemoglobin color
Mauve lavender color
Sulfhemoglobin in vitro formation
Forms when hydrogen sulfide is added to Hb
Sulfhemoglobin in vivo formation
Forms due to oxidation by certain drugs and chemicals
Sulfhemoglobin risks
Can lead to decreased oxygen delivery due to irreversible nature