Anemia Labs & Porphyrias

Possible causes of WBC abnormalities

Infection, inflammation, neoplasm/malignancy, drug reactions

Possible causes of hemoglobin/hematocrit abnormalities

Anemia, polycythemia

Possible causes of platelet abnormalities

Bleeding disorders, hypercoagulable states

RBC count

# of RBCs in a specified volume of whole blood, affected by volume status

Possible causes of increased RBC count

Dehydration, COPD, smoking, high altitude, polycythemia vera

Possible causes of decreased RBC count

Blood loss, anemia (Fe deficiency, B12/folate deficiency, hemolytic anemia, bone marrow failure), fluid overload (cirrhosis, pregnancy, CHF)

Hematocrit

Percentage of the total volume of RBCs relative to total volume of whole blood, affected by fluid status and RBC size

Relationship between Hct and Hgb

Hct = ~3x Hbg

MCV

Measure of average RBC size

MCV < 80

Microcytic

MCV 80-100

Normocytic

MCV > 100

Macrocytic

Microcytic

Little RBCs

Normocytic

Normal-sized RBCs

Macrocytic

Large RBCs

MCH

Weight of Hgb in RBC

MCHC

Hgb concentration (color)

Hypochromic

Normochromic

Hyperchromic

RDW

Measure of variation of RBC size

Anisocytosis

Condition characterized by RBCs of variable and abnormal size

Blood disorders diagnosed via peripheral smear

Leukemia, myelodysplastic syndrome, certain anemias, lymphoma, malaria

Rouleaux formation

RBCs clump together and form what looks like "stacks of coins"

Condition classically associated with rouleaux formation

Multiple myeloma

RBC agglutination

RBCs clump together

Conditions associated with macro-ovalocytes

B12 and folate deficiency

Condition associated with helmet cells and red blood cell fragments (schistocytes)

Defective heart valve

Spherocytes

Small, dense, hyperchromic RBCs lacking the normal central pallor

Condition associated with spherocytes

Hereditary spherocytosis

Conditions associated with Burr cells (echinocytes)

Metabolic disease like uremia or liver disease

Condition classically associated with basophilic stippling

Lead poisoning

Reticulocytes

Immature RBCs with retained RNA

Ferritin levels in iron deficiency

Low

Ferritin levels in iron excess

High

Possible causes of low serum iron

Acute or chronic blood loss, chronic disease, low dietary intake

Possible causes of high serum iron

Hemochromatosis, excessive dietary intake or supplementation

TIBC levels in iron deficiency

High

TIBC levels in iron overload

Low

Transferrin levels in iron deficiency

High

Transferrin levels in iron overload

Low

Transferrin saturation in iron deficiency

Low

Transferrin saturation in iron overload

High

Hemoglobin electrophoresis use

Detects hemoglobinopathies (i.e. Sickle cell anemia)

Most common cause of macrocytic anemias

B12/folate deficiency

Most common cause of hypersegmented neutrophils

Megaloblastic anemia

Diagnosis of vitamin B12 deficiency

Cobalamin level < 200 pg/mL

Confirmatory test for vitamin B12 deficiency

Elevated serum methylmalonic acid (MMA)

Length of folate storage in the body

2-3 months

Diagnosis of folic acid deficiency

Serum folate < 2 ng/mL

Confirmatory test for folate deficiency

Elevated homocysteine level (& normal MMA)

Factor assessed by reticulocyte count

Effectiveness of erythropoiesis

Causes of increased reticulocyte count

Acute bleeding, chronic blood loss, hemolysis, erythropoietin, iron/B12/folate ingestion, bone marrow transplant

Causes of decreased reticulocyte count

B12/folate/iron deficiency anemia, CKD, bone marrow failure, aplastic anemia, radiation therapy, some malignancies

Positive test that provides evidence for an immune etiology for hemolysis

Direct Coomb's test

Cause of low haptoglobin levels

Hgb hemolysis

Porphyrias

Disorder based on enzyme defects in porphyrin metabolism

Most common porphyrias

Porphyria cutanea tarda, Acute Intermittent Porphyria,

Erythropoietic protoporphyria

Porphyria Cutanea Tarda (PCT) inheritance

Autosomal dominant

Porphyria Cutanea Tarda (PCT) cause

Deficiency of urobilinogen decarboxylase

Porphyria Cutanea Tarda (PCT) associations

Hepatitis C, AUD, HIV

Porphyria Cutanea Tarda (PCT) clinical manifestations

Vesicles and bulla in dorsa of hands, scarring and small milia, hypertrichosis, mottled pigmentation