Heme II Unit #1.1

Proficiency Testing. Lyophillized serum, prepared slides or images

external quality control. Whole blood,

(1.85 × 10³)(100-Hct)V = C

Correction formula for proper volume of anticoagulant

Preanalytical Issues

overcoagulation and undercoagulation

Less than 90% of expected volume

Reject specimen. Specimen is over-anticoagulated

Hct is greater than 55%

Specimen is over anticoagulted

Quantitative QC

two levels done daily

Qualitative QC

positive and negative control each day

Coagulation QC

tested every 8 hours

Bull’s Testing Algorithm (X-B Analysis)

Method of using RBC indices to monitor using moving average from each group of 20 patients. Acceptable is ± 3%. Dependent on patient population or could be true alert

Artificial elevation of Hgb

lipemia, icterus, or hemolyiss in plasma

Corrected Hgb Calculation

Hgb determination performed on supernatant. Hgb original - Hgb supernatant

Saline Replacement

Plasma removed and replaced with equal volume of saline

Hemolysis

thromboplastin-like substances released, shortened clotting times

Lipemia or Icterus

can affect endpoint detection on photo-optical analyzers

Anemia

decreased O2 carrying capacity of blood. Occurs when destruction/loss exceeds marrow capacity

Erythrocyte Kinetics

marrow can compensate 5-8x normal output

Hypervolemia

increased plasma volume. Hgb/Hct fasely low relative to RBC

Hypovolemia

decreased plasma volume. Hgb/Hct falsely high or normal

Acute Blood Loss

initially normal Hgb (RBC mass and plasma volume drop together). Falls as plasma re-expands

20% Acute Blood Loss

blood volume tolerated

30-40% Acute Blood Loss

Blood loss that causes shock

50% Acute Blood Loss

Blood loss that causes death

Chronic Anemia

adaptive mechanisms let organs function at Hgb up to 50% below normal

Pallor

conjunctiva, nailbed, palm, tongue

Jaundice and Dark Urine

suggets hemolytic process

Splenomegaly / Hepatomegaly

chronic hemolytic or infiltrative disease

Koilonychia

iron deficiency

Smooth Tongue

megaloblastic anemia

Bone Deformities and expansion in children

chronic severe hemolytic anemia

Reticulocyte Count

indicates marrow response

Peripheral Smear

indicates morphology, inclusions, and distribution

Bilirubin

indicates hemoglobin catabolism

Urine and Stool

indicates occult blood, urobillinogen

Microcytic and Hypochromic

defective hgb synthesis

Macrocytic

impaired DNA snythesis (B12/folate) or reticulocytosis

Absolute Retic Count

% retics x RBC count. Reference 25 - 75 × 10³

Corrected Retic %

% retic x (patient Hct / normal Hct). Normal Hct 45%

Reticulocyte Production Index (RPI)

corrected retic % / maturation time. lower hct means earlier retics were pushed out of bone marrow

RPI >2

appropriate marrow response

Immature Reticulocyte Fraction (IRF)

least mature retic fraction, highest RNA content. Earliest sign of marrow response

Reticulocyte Hemoglobin

Hgb content of circulating reticulocytes. Reflects iron over last several days

Proliferation Defect

decreased production. normo, decreased retic, RPI < 2

Maturation Defect

ineffective erythropoiesis. nuclear (megaloblastic) and cytoplasmic (hgb synthesis)

Survival Defect

increased destruction or loss. increased retic. increased IRF. RPI > 2

Intrinsic Hemolysis

hereditary. membrane, enzyme, or hemoglobin defects, usually extravascular

Extrinsic Hemolysis

acquired. Extra or intravascular, antibody, mechanical, chemical, or infectious injury

Serum Bilirubin

from Hgb catabolism, usually even with active hemolysis

Haptoglobin and hemopexin

consumed clearing free Hgb/heme, both decrease with hemolysis

Lactate Dehydrogenase

released from lysed cells, most elevated in intravascular hemolysis

Urine hemosiderin and urobilinogen

reflect hemoglobin catabolism products

DAT

detects antibody/complement coated RBC

Homogenous

normal RDW. hypoproliferative anemias, chronic disease, some hemoglobinopathies

Heterogeneous

Increased RDW. nutrition deficiencies, early iron deficiency, dimorphic populations, uncompensated hemolysis

Decreased M:E Ratio

hemolytic anemia (marrow compensating)

Increased M:E Ratio

proliferation defect

Screening Tests

high sensitivity, positive when disease present

Confirmatory Tests

high specificity. Negative when disease is absent

Reflex Testing

one result guides the next test ordered

Defective hgb synthesis

results in cytoplasmic maturation defects - microcytic and hypochromic anemia

Heme Synthesis

deficient iron, defective regulation of iron metabolism, defect in porphyrin synthesis

Globin Synthesis

gene mutations/deletions (thalassemia)

Transferrin

iron transport protein

Heme Iron

ferrrous (fe2+), from red meat, absorbed efficiently

Nonheme iron

ferric (fe3+), from vegetables/whole grains. Converted to Fe2+ to be absorbed

Ferrtin

polar iron storage that is readily available.

Ferroportin

acts as iron exporting molecule

Retic Count and Indicies

mean hgb content of retics, measures availabilty of Fe during hgb synthesis

Serum Iron

how much iron is present in the serum

TIBC (Total Iron Binding Capacity)

how much iron is present if completely filled up

UIBC (unsaturated iron-binding capacity)

how much empty iron remains

Serum Iron + UIBC = TIBC

how to calculate TIBC from serum iron and UIBC

Transferrin Saturation

how much iron is currently there in %

(Serum iron / TIBC) x 100

Transferrin Saturation formula

Zinc Photoporphyrin (ZPP)

when iron is not available, zinc is incorporated into heme

Hemosiderin

partially degraded insolulbe ferritin in macrophages and tissues. releases iron slowly

Hepcidin

liver produced hormone that binds and degrades ferroportin. More means less absorption of iron

Ferrochelatase

inserts Fe2+ into protoporphyrin 9 to form heme

IDA causes

blood loss, poor diet, malabsorption, and increased demand for iron

Stage 1: Iron Depletion

iron stores are exhausted, RBC morph is normal, no anemia

Stage 2: Iron Deficient Erythropoiesis

insufficent iron to insert into protoporphyrin ring. RBC slightly microcytic

Stage 3: Iron Deficiency Anemia

all lab tests are abnormal, microcytic hyprochromic anemia

IDA Therapy

treat underlying cause of iron deficiency, administer iron oral or parenteral

Anemia of Chronic Disease

hepcidin traps iron in tissues and macrophages, iron stores remain normal

Sideroblastic Anemia

ring sideroblasts on marrow during prussian blue stain. Iron accumulation

Sideroblastic Causes

hereditary - X linked, and variant of enzyme ALAS2 (first step in heme synth)

Acquired - malignancy, alcohol, lead, zinc, vit B6 deficiency

Iron Overload

excess iron deposits in liver, heart, and pancreas

Hereditary Hemochromatosis

lack of hepcidin causes increased iron absorption. Primary iron overload. Occurs in HFE gene

Secondary Iron Overload

repeated transfusions or ineffective erythropoiesis