Lab Values

WHAT IS TESTED?

• Most lab tests use peripheral venous blood

• Other body fluids may be tested as well:

• Sputum

• Urine

• Pleural Fluid

• Cerebrospinal Fluid

• Feces

• Sweat

COMPONENT

S OF BLOOD

• Formed Elements – made in the bone marrow

from stem cells

• Red Blood Cells (erythrocytes)

• White Blood Cells (leukocytes)

• Platelets (thrombocytes)

• Plasma

• Contains electrolytes, clotting factors,

immunologic factors, proteins, lipids,

hormones

• Almost all the substances used by cells are

carried by the plasma

EVALUATING LAB RESULTS

• Normal values are expressed in a range that includes 95% of the normal

population (+/- 2 standard deviations)

• Each lab has to determine their own values using their particular equipment

and methods

• Possible to obtain a normal test for a patient with a disease or healthy patients

to have abnormal test results

• Evaluate results in light of other clinical findings

HEMATOLOGY

• Complete Blood Count – counts and differentiates white and red blood

cells

• White Blood Cells – primary role is to fight infection

• Neutrophils – most common, segmented and bands

• Eosinophils and Basophils – interact in allergic reactions, eosinophils

also fight parasitic infections

• Lymphocytes – T cells involved in cell mediated immunity, B cells in

antibody production

• Monocytes – phagocytosis of organisms and foreign material

HEMATOLOGY

• Red Blood Cells

• Produced in the bone marrow, lifespan of 120 days

• Primary function is to carry oxygen, made up mostly of hemoglobin

• Low RBC count impairs ability of blood to transport O2

• Normal RBC count does not mean a normal Hb level or normal O2

carrying capacity

• Hematocrit – ratio of red cell volume to that of whole blood (determined by

centrifuging)

• Hemoglobin – as above and also carries CO2 from tissues to the lungs

HEMATOLOGY

• RBC Indices

• Mean cell volume, Mean cell Hb, Mean cell concentration – used to

evaluate and classify anemias

• Anemia vs. Polycythemia

• Platelets – important in blood coagulation, platelets form blood clots

• Coagulation studies

• Bleeding time

• APTT

• PT/INR

CHEMISTRY

• Electrolytes – free ions in body fluids

• Normal function of all cells depend upon proper concentration

• Monitoring very important in patients with body fluid problems (renal

disease, IV therapy, diarrhea)

• Anion Gap

• Sweat Chloride

• Blood Urea Nitrogen (BUN) and Creatinine

• Indications of renal function

• Enzymes – liver, pancreatic, cardiac

CHEMISTRY

• Glucose – produced from digestion of carbohydrates

• Hypo/Hyperglycemia

• Proteins – needed for normal metabolic function and is the main

building substance of the body

• Total protein, Albumin

• Lipids

• Triglycerides and Cholesterol

• Tumor markers

• Drug Monitoring