- too few red cells cause hypoxemia

- increased cardiac output, respiration, shunting to vital organs, decreased hgb O2 affinity, increased EP

- tachycardia, shortness of breath, systolic flow murmur, fatigability, faintness, angina in elderly, dyspnea on exertion

Anemia

 - too many red cells cause hyperviscosity

polycythemia

- # of RBCs per unit of volume measurement of blood

(normal = 4.1-5.5 10^3/uL)

RBC count

- percent of the volume of whole blood occupied by RBCs

- length of tube after spinning occupied by packed RBCs divided by total length times 100%

- 3x hgb

(Normal = 37-50%)

Hematocrit

- measured by spectrophotometer after red cells lysed

- 1/3 of hematocrit

(normal = 12.5-17 GM/dL)

Hemoglobin concentration

- cause of males having more red cells than females

Testosterone

- hematocrit/RBC x 10

(normal = 87 +- 7)

- indicates average size of RBCs and is most important

Mean corpuscular volume (MCV)

- Hgb/Hct x 100

(normal = 34 +- 2)

- lesser --> paler cell

Mean corpuscular Hgb concentration

 - degree of variation of size (anisocytosis) and shape (poikilocytosis)

- what % of red cells have volume bigger/smaller than normal range

(normal = 13.1% +- 1.5%)

- greater variation of volume = greater the percent

Red Cell Distribution Width (RDW)

- low MCV (microcytosis) + high RDW

Iron Deficiency

- low MCV + normal RDW

Thalassemia

- red cell loses nucleus --> reticulocyte (residual, stainable RNA)

- bluish w/ Wright-Giemsa stain, better w/ reticulocyte stain (RNA stain)

- marrow for 2 days before entering blood

- reticulocyte loses RNA after 24 hours --> mature RBC

Erythropoiesis

- main site of synthesis

- hypoxia here causes increased erythropoietin production

Kidney

- cause of decreased EP production --> anemia

- treated with erythropoietin

Chronic renal failure

- RBC loses enzymes, swells, loses deformability, phagocytized by macrophages in marrow and spleen

- 1 in 100 red cells per day (normal)

- after 100-120 days

red cell death

- measure of RBC produced in last 24 hours

- expressed as a ratio

- normal = 0.5-1.5%

- doubled with 1/2 the hematocrit

Reticulocyte count

- standardized retic counts

- raw reticulocyte ratio times the red cell count

- normal = 20-100 x 10^3/uL

Absolute reticulocyte count

- 1st study to see if anemia is due to failure of production or survival

- high retic = survival failure

- low retic = production failure

Reticulocyte count

- MCV is helpful in determining this type of RBC failure

Marrow failure

- blood loss

- failure of RBC survival/hemolysis

- decreased production from marrow failure

- decreased production from ineffective erythropoiesis w/o marrow problems

Causes of anemia

- rate of loss > rate of production

(more than 4x normal marrow production)

- retic count normal for 1st 48 hrs

- hgb/hct normal for 1st 12 hrs

Blood loss anemia

- retic count elevated

- extrinsic damage to normal cells (physical destruction, hypersplenism, immune hemolytic anemia)

- intrinsic damage to normal cells (defective membrane, hgb, enzymes)

Failure of survival (hemolysis)

- blood cells are trapped and destroyed in this organ as it gets bigger and bigger

- caused by cirrhosis or lymphoma/leukemia

hypersplenism

- detected by anti-human antibody (Coombs test)

- auto-immune dx, blood transfusion, pregnancy

- high retic count, Cold-IgM, Warm-IgG, jaundice if severe

Immune hemolytic anemia

- rabbit antibody generated against human Ig's

- red cells covered by human Ab's will agglutinate or be lysed w/ this

Coombs reagent

- detects human anti-red cell Ab's on patient's RBCs

Direct Coombs test

- detects human anti-red antibodies on patient's plasma/serum

- done with transfusion cross match & screening

- done w/ Rh- mother

Indirect Coombs test

- Mother negative direct, positive indirect

- Fetus positive direct, positive indirect

- Father negative for both

Coombs Test Results

- defective hgb that is detected w/ hgb electrophoresis

- mutation causes decreased synthesis of hgb chain w/o changing AA's in chain

- results in excess of other chain, which precipitates out --> destroyed RBC by phagocytosis

- decreased hgb --> microcytosis

- family hx/mediterranian origin

Thalassemia

- mutation changes one or more AA's of hgb chain

- results in decreases solubility --> crystalized hgb altering RBC shape --> phagocytic destruction and vascular occlusion (ischemia)

Hemoglobinopathy

- enzyme defect that causes phagocytosis of RBCs and degradation of hgb

- high retic count, no strange red cells

- 10% of black males

- Heinz body stain, Hx of oxidizing agent

G-6-PD deficiency

- low retic count w/ lack of marrow precursors for ALL blood cell lines (only fat left in marrow)

- pancytopenia

- normal MCV

Aplastic anemia

- normal MCV

- low retic count w/ lack of marrow precursors (erythroblasts only)

- anemia w/o neutropenia or thrombocytopenia

- kids parvoviral infection "aplastic crisis"

- adults thymic lesion

Pure red cell aplasia

- low retic count

- cessation of erythropoietin production, decreased erythroblasts

- anemia w/o neutropenia or thrombocytopenia

Renal failure

- replacement of marrow by tumor, fibrosis or granulomas

- anemia, thrombocytopenia and/or neutropenia

- low retic count

- normal MCV

Myelophthisis

- low retic count, low MCV, serum ferritin decreased, serum Fe low & TIBC high, % Fe saturation < 10%

- defective red cells, microcytosis

- dietary or chronic bleeding problem

Iron deficiency

- normal/high serum ferritin, serum Fe & TIBC both low, % Fe saturation > 15%, inflammation, increased ESR

- chronic inflammation causes microphages to hoard iron

- usually normocytic anemia but can cause microcytosis

Anemia of chronic disease

- caused by lack of B12, folate

- deficiency in thymidine and inhibited nuclear replication

- macrocytosis

Megaloblastic anemia

- low retic count, low MCV, serum ferritin decreased, serum Fe low & TIBC high, % Fe saturation < 10%

Iron Deficiency