7: Lab Evaluation of RBCs

MCV

average volume of ONE RBC

MCH

average amount of Hb in ONE RBC

what affects MCH value?

cell size and internal Hb concentration

when is MCH the lowest?

when MCV/MCHC values are also low

RDW

coefficient of variation of red cell volume

macrocytosis

high MCV

what could cause high MCV (macrocytosis)

hemolytic REGENERATIVE anemia, FeLV, immune-mediated anemia

microcytosis

low MCV

what could cause low MCV (microcytosis)

chronic Fe deficiency, liver shunts, anemia of inflammatory disease

what could cause low MCHC?

REGENERATIVE anemias, chronic Fe deficiency, hereditary stomatocytosis

what causes high MCHC?

ARTIFACTS (vivo/vitro hemolysis, Heinz bodies, lipemia, agglutination)

what causes an increase in RDW?

large reticulocytes, Fe deficiency, fragmentation

coombs test

a blood test to diagnose hemolytic anemias

major blood cross-match is most important for:

RBC transfusions

how to test for a major blood cross-match

use donor RBCs and recipient serum

testing for a major blood cross-match. what are we looking for?

RBC antibodies in recipient

minor blood cross match is important for:

neonatal isoerythrolysis or plasma transfusions

how to test for a minor blood cross-match

use donor serum and recipient RBCs

when does iron metabolism INCREASE?

when total body Fe is low or erythropoiesis increases

when does iron metabolism DECREASE?

when total body Fe is high or inflammation is present

what does hepcidin do?

inhibits Fe release from entero/hepatocytes and macrophages

erythroferrone is produced. what should we suspect?

RBC hyperplasia

what does erythroferrone do?

systemically regulates Fe

what binds iron in the bloodstream?

transferrin

serum iron has INCREASED. what should we suspect?

hemolytic/hypoplastic/aplastic anemia, Fe overload, glucocorticoids (dogs/horses)

serum iron has DECREASED. what should we suspect?

Fe deficiency, anemia of inflammatory disease, liver shunt, glucocorticoids (cattle/goats)

ferritin has DECREASED. what should we suspect?

Fe deficiency

ferritin has INCREASED. what should we suspect?

Fe overload, hemolytic anemia, inflammation,

how does hypoxemia cause cyanosis?

low arterial pH

what can cause methoemoglobinemia?

oxidant chemicals, Cu, bok choy

clinical signs of methemoglobinemia

cyanotic skin/MMs, lethargy, ataxia, rapid HR/RR, coma

hereditary methemoglobinemia

just have cyanotic appearing skin (like on tongue).

what determines EPO concentration?

kidney production and utilization by RBCs

EPO is INCREASED. what should we suspect?

most anemias, SECONDARY erythrocytosis

erythrocytosis

abnormal increase in the number of red blood cells

EPO has DECREASED. what should we suspect?

CKD, PRIMARY erythrocytosis

Primary erythrocytosis

Increase in RBCs due to disease.

secondary erythrocytosis

Increase in RBCs; compensatory mechanism.

true or false: methemoglobinemia can produce cyanosis with NORMAL ARTERIAL PH

TRUE