South College AVL Lab Med: Anemia and Vitamins - Lecture 3

Reticulocyte

immature erythrocyte

(reticulocytes/total RBCs) x 100

(normal: 0.5-2%)

how do you calculate reticulocyte count %?

the reticulocyte index (RI) or corrected Retic count

What does obtaining the reticulocyte count % allow you to calculate?

RC% x (patient Hct/normal Hct)

(normal Hct: 45)

how do you calculate the reticulocyte index (RI)?

decreased bone production: DAMAGED BONE MARROW (aplasia, drugs, fibrosis, infiltration), renal disease (decreased EPO), Iron deficiency, chronic inflam. disease, nutritional deficiencies (Fe, B12)

What would be some causes of decreased RI? (<2.5%)

increased destruction: BLOOD LOSS (GI, heavy menstruation), HEMOLYSIS - intrinsic (G6PD, Sickle Cell, Malaria) and extrinsic (disseminated intravascular disease (DIC), thromobotic thrombocytopenic pupura (TTP), hemolytic uremia syndrome (HUS), mechanical heart valve)

What would be some causes of increased RI? (>2.5%)

1. complete CBC w/ diff

2. If abnormality seen w/ CBC - peripheral smear (shows size - anisocytosis, shape - poikilocytosis, and color on slide)

What are the first steps of Anemia/Iron deficiency workup?

average size of RBCs, mean corpuscular volume (MCV) on CBC, MACROCYTIC > 100 fL, NORMOCYTIC 80-100 fL, MICROCYTIC <80 fL

What are some morphologic considerations when classifying anemia?

BIG FAT RED CELLS

What is the pneumonic to remember macrocytic causes?

Iron Studies

What are some other considerations for anemia/iron deficiency work up after CBC w/ diff and peripheral smear?

NORMAL SIZE

What is the pneumonic to remember normocytic causes?

NORMAL SIZE

normal preg (30% plasma increase), overhydration, renal disease, marrow infiltration (infection, fibrosis, leukemia), acute blood loss, liver diease, systemic inflammation (chronic disease), iron deficiency (early/new), zero production (aplasia, aplastic anemia), endocrine disorder (thyroid, adrenal)

****(chronic disease = normocytic 70% of the time)

What are some causes of normocytic cells (80-100 fL)?

TICS

What is the pneumonic to remember microcytic causes?

TICS

thalassemia, iron deficiency, chronic inflammation, sideoblastic and lead poisoning

******(MCV<70 = Fe deficiency or thalassemia and chronic disease/inflammatory = microcytic 30% of the time)

What are some causes of microcytic cells (<80 fL)?

BIG FAT RED CELLS

B12 deficiency, inherited disorder, GI surgery/illness, folic acid deficiency, alcoholism, thiamine-responsive anemia, reticulocytes (falsely elevated), endocrine disorders (hypothyroid), dietary deficiencies, chemotherapy, erythroleukemia (immature blasts), liver disease, lesh-nyhan syndrome, splenectomy

What are some causes of macrocytic cells (>100 fL)?

Iron Studies

used to evaluate iron metabolism when iron deficiency, overloading, or poisoning is suspected

serum iron (Fe), total iron binding capacity (TIBC), transferrin, transferrin saturation, ferritin

What are the components of an iron study?

Serum Iron

measure of iron circulating in the blood

Total Iron Binding Capacity (TIBC)

Measure of of all proteins available to bind to iron.

iron deficiency anemia (plenty of room for iron to bind)

What disease do we care most about where Total Iron Binding Capacity (TIBC) are HIGH?

Transferrin

iron transport protein - helps transfer iron since ferritin is immobile - produced in the liver (MOST COMMON TRANSFER PROTEIN)

iron deficiency anemia

What disease do we care most about where transferrin levels are LOW?

Transferrin saturation

Percentage of transferrin bound to iron - screens for iron overload

ferritin

immobile, used to bind and store iron - this measures how much iron storage there is in the body

iron deficiency anemia

When are ferritin levels LOW (only disease w/this)?

NO - DANGEROUS

Is free iron in the blood safe?

Fe2+ (Fe3+ needed to be reduced to Fe2+)

What is the absorbable form of iron?

Enterocytes (line the duodenum)

What absorbs iron?

liver (storage) and bone marrow (erythropoesis)

Where does iron in the GI tract need to be transferred to?

stiffen, structural proteins that allow for flexibility are broken down (stiff RBCs get stuck in small capillaries - spleen)

What happens as RBCs age?

Macrophages - ingest and breakdown Hgb, Fe is recycled (ferritin - liver - storage), and heme is broken down into bilirubin (sent to liver - bile)

How do we deal with old, stiff RBCs trapped in small capillaries (spleen)?

insufficient diet, chronic blood loss, inadequate intestinal absorption, pregnancy

What are some causes of decreased serum iron levels?

hemochromatosis, hemosiderosis (iron in liver, pancreas, skin)

What are some causes of increased serum iron levels?

Hemosiderosis

excessive accumulation of iron deposits (hemosiderin) in tissues

blood transfusions, high iron meals, hemolytic diseases (high), meds

What are some interfering factors of serum iron?

unsaturated iron binding capacity (UIBC) + serum iron

how do we calculate total iron binding capacity (TIBC)?

pregnancy, estrogen therapy, iron deficiency anemia, polycythemia vera (overproduction of RBCs in bone marrow)

What are some causes for increased TIBC?

acute inflammatory disease, chronic disease (ex: liver disease), malnutrition/proproteinemia, hemolytic/pernicious/sickle cell anemias (pathophys unclear)

What are some causes for decreased TIBC?

negative (DECREASES during inflammation - likely due to decreased liver function during inflammatory response)

What type of acute phase reactant (APR) is transferrin?

SAME AS TIBC - pregnancy, estrogen therapy, iron deficiency anemia, polycethemia vera (overproduction of RBCs in bone marrow)

What are some causes for increased transferrin?

acute inflammatory disease, chronic disease (ex: liver disease), malnutrition/proproteinemia, hemolytic/pernicious/sickle cell anemias (pathophys unclear)

What are some causes for decreased transferrin?

(serum iron x 100%)/TIBC

How do we calculate transferrin saturation?

1. hemolytic/sideroblastic/megaloblastic anemias

2. iron overload/poisoning

What are some causes for increased transferrin saturation?

1. iron deficiency anemia

2. chronic illness

What are some causes for decreased transferrin saturation?

Ferritin

What lab value will likely precede other signs of anemia?

hemochromotosis/hemosiderosis, megaloblastic/hemolytic/alcoholic anemias, inflammatory diseases, advanced cancers, chronic diseases (ex: hepatitis)

What are some causes of increased ferritin?

iron deficiency anemia, severe protein deficiency, hemodialysis

What are some causes of decreased ferritin?

ferritin levels (DECREASED)

what is the most sensitive test in determining the presence of iron deficiency anemia?

chronic diseases (falsely ELEVATED b/c ferritin = APR), APR protein (can be ELEVATED in conditions not reflecting iron storage - acute inflammatory diseases, infections, metastatic cancer, lymphomas)

What are some interfering factors of ferritin levels?

INSERT DISEASE CHART

INSERT DISEASE CHART

Vitamin B12

Necessary for RBC production (converts inactive folate - active folate)

ingestion of animal protein - intrinsic factor (IF) to absorb B12 (depends on normally functioning intestinal mucosa for absorption)

How do we obtain vitamin B12?

pernicious anemia

B12 deficiency due to lack of intrinsic factor in body

yes!

Do we need to fast for vitamin B12 lab collection?

leukemia, polycythemia vera, severe liver dysfunction, myeloproliferative diseases

What are some causes of increased vit B12?

pernicious anemia, malabsorption syndrome, folic acid deficiency, alcohol use disorder, large proximal gastrectomy, resection of terminal ileum, pregnancy, vit C deficiency

What are some causes of decreased vit B12?

metformin usage > 4 months, PPI usage > 1 year (proton pump inhibitor - ex: omeprazole)

What are some interfering factors of vit B12 levels?

pancytopenia

a condition where there is a lower-than-normal number of red and white blood cells and platelets in the blood

B12 deficiency (due to role in early blood cell formation)

what can cause pancytopenia?

methylmalonic acid (MMA)

What is the most sensitive test for B12 deficiency?

B12 deficiency

What would high serum and urine MMA levels suggest?

L-methylmalonyl-CoA (MMA Coa) to succinyl CoA

Active form of B12 is needed to convert what to what?

large quantities of MMA are made - excreted by kidneys (hence high urine MMA)

Without B12, what happens to MMA CoA?

Folate deficiency

What needs to be considered if B12 is elevated, but MMA is normal?

MMA is excreted by the kidneys (levels can be misleadingly elevated)

Why is MMA unreliable for renal insufficiency?

folic acid (folate or vit B9)

Necessary for WBC and RBC function, formed by bacteria is intestines - stored in liver

helps cells grow/multiply, helps form RBCs, helps form genetic material (RNA/DNA), keeps brain/nervous system functioning, supports brain development during pregnancy/infancy, balance homocysteine (amino acid) levels in blood

What are some functions of folic acid?

pernicious anemia, increased alcohol use, vegetarian lifestyle, blood transfusion

What are some causes of increased folic acid?

malnourishment, malabsorption syndrome, pregnancy, hemolytic anemia, liver disease, CKD (chronic kidney disease)

What are some causes of decreased folic acid?

alcohol, pregnancy, meds

What are some interfering factors of folic acid?

vitamin D

fat soluble vitamin

Cholecalciferol (D3) - synthesized by skin due to UV-B exposure/radiation

Ergocalciferol (D2) - food

Converted in liver and kidney - active form

How do we obtain active form of vitamin D (1,25-dihydroxyvitamin D)

INSERT VIT D3 SYNTHESIS/ACTIVATION

INSERT VIT D3 SYNTHESIS/ACTIVATION

1,25(OH)2D (calcitriol)

What is the most sensitive measure of Vit D?

helps form/keep bones and teeth strong, helps w/ muscle contraction, helps nerve carry messages between brain and body, supports immune system

What are some functions of Vit D?

Rickets, Osteomalacia/osteoporosis, inadequate dietary intake/sun exposure, liver/renal disease, acute inflammatory disorders, malabsorption syndrome

What are some causes of decreased Vit D?

Williams syndrome, supplement intake

What are some causes of increased Vit D?

increased HTN and CV risk, increased rate of infections, colon/breast/pancreatic cancers

Decreased levels of Vitamin D are linked to?

steroid use (can reduce calcium absorption)

what are some interfering factors of vit D?

inadequate sun exposure/dark skin, higher in black/hispanic individuals, female/elderly/obese, low socioeconomic status, latitudes higher than 38 degrees (colder/darker climates), institutionalized/depression, breastfed infants, meds, malabsorption syndromes, individuals who wear long robes/head coverings, liver or renal disease

What are some vitamin D deficiency risk factors?