AAB Hematology questions and answers.

Hemoglobin composition 4 heme ( 4 Fe + 1 porphryin) 1 globin ( 2 alpha 2 beta chains) Mw= 64000 Porphyria abnorm of heme synth xs production of intermediate metabolite protein unchanged change in valence of iron or organic group oxyhemoglobin O attaches to Fe ++ ( reduced hgb), replacing water molecule carry O, iron is kept at Fe++ ( ferrous) state by methemoglobin-cytochrome C reductase carboxy hemoglobin binding of CO2 is 200x stronger than for O heavy smokers 6-10% of total hgb can be hbCO methemoglobin Ferrous iron has become ferric ( Fe+++) methHb cant bind O ( cyanotic) nitrate ingestion= rapid oxidation and enz cant keep pace and methb forms 630-633 nm- evelyn malloy method lipemic- saline Sulfhemoglobin ingestion of silfur drug or chronic constipation sulfer blood build up cant carry oxygen irreversible change in RBC until removed toxic= 0.5 g/dL not measured by cyanmethemoglobin method color of reduced hb purple- red color of HbO2 bright red color of HbCO cherry pink how to diff hgb derivatives differential spectrophoto or gas chrome 3 ways protein changes of hg both chains of either pair ( alpha or beta) are replaced fragments of chains are replaced single AA changed adult Hb most is Hb-A_1 ( alpha_2 beta _2) small amounts of HB-A_2 ( alpha _2 delta _2 trace amounts of Hb-F ( alpha_2 gamma_2) when body cant make normal beta chains, it uses gamma or delta abnormal hb example 4 gamma chains or hgb Barts 4 beta chains- hg H embryonic hemoglobin gowers 1 ( 2 zeta 2 epsilon) gowers 2 ( 2 alpha 2 epsilon) portlan ( 2 zeta 2 gamma) gowers 1 ( 2 zeta 2 epsilon) gowers 2 ( 2 alpha 2 epsilon) portland ( 2 zeta 2 gamma) newborn hb content most hb-F some A_1 thalassemia most HbA1, inc in A2 and F sickle cell disease most Hb-S, some F occasionally some A2 sickle cell trait Hb-AS ratio of 60% A1, 40% S HbS single AA replacement 6th AA on beta chain neutral charge replaces negative ( slower migration) HbS soluble if oxygenated - less sol if reduced - under conditions of O deprivation - formation of tactoids ( fluid crystals) - crystals are riged and deform the RBC to sickle speed of sickling not related to amount of hb-s severity of disease diff of Hb- SS and Hb- AS is electrophoresis screening for sickle cell forms wet prep - unhemolyzed blood - deprive sample of oxygen - sodium metabisultfite ( reducing agent) hastens rate of sickling solubility test is for screening procedure for Hb-S or any sickling hemoglobin ( Hb-C georgetown or harlem) reagents for solubility test for SS saponon( hemolytic agent) sodium dithionite ( reducing) monobasic/dibasic potassium phosphate ( strong buffer) specimen for solubility test for SS fresh blood , slight hemo doesnt interfere pos results for solubility test for SS turbidity false neg for solubility test for SS reading with bright light failure to use 2x usual amount of blood in patients with < 7 g/dL Hb less than 10% hb-s present ( recent transfusion) fals pos for solubility test for SS hyperlipidemia hypergammaglobulinemia - repeat with plasma, if still turbid cause is globulin or lipid If color is orange yellow instead of purple for solubility test for SS add more dithionite, if blood + reagent not clear, saponin is inert combination of any other Hb with Hb-s lessens severity of ss anemia Hb-C lysine replaces glutamic acid at 6th aa of beta chain - pos charge replaces negative - becomes cathodial ( positive) on elec tetragonal crystals makes rbc rigid, not O dependent biscuit folded cells and target cells Hb-F 2 gamma chains replace 2 beta chains - diff mobility on elec - resistance to acid /alkaline elution alkaline denaturation test hb soln+ KOH stop with (NH4)2SO4, lowers pH report presence of fetal hemoglobin Kleinhaur technique for detection of fetal redblood cells in maternal circulation Acid phosphate buffer elution Hb-F resists elution