To follow up with the “handy reference cheat sheet” series from my previous blog post (A Quick Reference for Common Adult Lab Values Part 1), I will review hematological lab value references. Today’s chief focus will include interpretations of lab values for complete blood cell count (CBC), white blood cell count (WBC) with differential, anemia, anticoagulation, and a transitory discussion of drug-induced hemolytic anemia in Glucose-6-phospahte dehydrogenase (G6PD) deficiency individuals.
G6PD deficiency is the world’s most common x-linked heredity disorder, affecting some 400 million people (of African, Mediterranean, and Southeast Asian descent). A deficiency in G6PD causes red blood cells (RBC) to break down prematurely (hemolysis) due to reduction of the membrane’s integrity. Hemolysis typically ensues oxidative stress from acute fever/bacterial infections, diabetic acidosis, neonatal hyperbilirubinemia, fava beans and, last but not least, oxidative drugs.
Common symptoms frequently consist of pale skin, jaundice, dark colored urine, transient splenomegaly, hepatomegaly, abdominal pain, hemoglobinuria, and increased heart rate.
Diagnosis: Clinical findings of G-6-PD deficiency are characterized by bite cells (also known as blister cell), Heinz bodies, reticulocytosis (an increase production of immature red blood cell), and an abrupt decline in hemoglobin concentration. The use of florescent spot tests can sufficiently establish diagnosis by detecting G6PD enzymes deficiency. A false negative diagnosis is conceivable in acutely, active hemolytic episodes, in which the affected RBCs are quickly cleared from circulation. Under these circumstances, the validity of the test is nulled, and should be repeated in a few weeks post a hemolytic episode.
Generally, diagnostic tests will reveal the following in hemolytic anemia in G6PD deficiency patients:
- Liver enzymes
- Lactate dehydrogenase (a good marker for gaging severity)
- ¯ RBC
- Presence of bite cells on smear
- Heinz bodies inside RBCS on stained blood smear (during early stages)
- Negative Coombs’ test (as hemolysis not induced by immune response)
Avoidance of triggers: A number of oxidative drugs can precipitate an acute episode of hemolytic anemia in patients with G6PD deficiency. Certain medications can interact with oxygen and hemoglobin to form and accumulate intracellular H2O2 (hydrogen peroxide) and oxidants, resulting in RBC destruction.
The following are some medications that should be avoided in G6PD deficiency patients:
- Sulfacetamide (Klaron)
- Mafenide (sulfamylon) Cream
- Nitrofural (Furacin)
- Nalidixic acid (synthetic floroquinolone)
- Anti-malaria agents
- Antineoplastic agent
- Flutamide (Eulexin)
- Rasburicase (Elitek)
- Aspirin-containing products, NSAIDS
- Fe (iron overload)
- Methylene blue
- Vitamin K3 & K4
For the extended, more detailed list of drugs and products to avoid, please visit G6PD Deficiency Association.
Adult lab references in the pipeline:
- cardiac markers
- thyroid functions
- blood gases
Feature photo credit: http://www.normadiagnostics.com/Index.aspx?MN=Hematology&LN=English
Heinz Bodies photo credit: https://www.studyblue.com/notes/note/n/cells/deck/2625830
Bite cells photo credit: https://www.studyblue.com/notes/note/n/heme/deck/10756608