Laboratory Values: A Guide to Understanding Lab Results
Laboratory test results account for almost 70% of medical decisions made by healthcare providers. Thus, medical professionals must be adequately trained in the execution of the tests, more so in interpreting laboratory values, which are the most critical components of medical data.
This article provides pharmacists and pharmacy technicians with a refresher regarding laboratory values. It includes their reference ranges, meanings, and medical implications.
What’s In The Article?
How to Interpret Basic Metabolic Panel (BMP) Values
How to Interpret Complete Blood Count (CBC) Values
How to Interpret Coagulation Test Values
Final Thoughts
How To Interpret Basic Metabolic Panel (BMP) Values
A Basic Metabolic Panel (BMP) is a test that calculates the presence of eight various substances in the blood.
Glucose Test.
It helps diagnose or monitor diabetes and insulin abnormalities. Normal laboratory values: 70-110 mg/dL if fasting Abnormally high amounts: suggest the presence of diabetes mellitus, acute stress response, or Cushing’s syndrome. Deficiency: suggests insulinoma, hypothyroidism, hypopituitarism, or Addison’s disease.
Calcium (Ca) Test.
It helps diagnose or monitor renal hyperparathyroidism and malignancies. Normal laboratory values: 9-10.5 mg/dL Abnormally high amounts: suggest hypercalcemia, hyperparathyroidism, lung and renal carcinoma, or Addison’s disease. Deficiency: suggests hypoparathyroidism, renal failure, rickets, or a Vitamin D deficiency.
Sodium (Na) Test.
It measures the amount of sodium in the blood, which is necessary for nerve and muscle functions. Normal laboratory values: 136-145 mEq/L Abnormally high amounts: suggest Cushing’s syndrome, excessive sweating, or diabetes insipidus Deficiency: suggests Addison’s disease, diarrhea, vomiting, diuretics, or Cushing’s syndrome.
Potassium (K) test.
It helps monitor renal function and maintain cardiac function. Normal laboratory values: 3.5-5.0 mEq/L Abnormally high amounts: suggest renal failure, hemolysis, infection, or acidosis. Deficiency: suggest burns, diarrhea, vomiting, diuretics, or Cushing’s syndrome.
Blood Urea Nitrogen (BUN) Test.
This test indirectly measures kidney function through liver function. Normal laboratory values: 10-20 mg/dL Abnormally high amounts: suggest hypovolemia, shock,
burns, dehydration, congestive heart failure (CHF), myocardial infarction (MI), gastrointestinal disease (GI), bleeding, orsepsisDeficiency: suggests liver failure, overhydration due to fluid overload (syndrome of inappropriate antidiuretic hormone secretion or SIADH), or malnutrition.
Creatinine (Cr) Test.
It directly measures kidney function. Creatinine is a residual chemical compound from energy-producing muscle processes. Normal laboratory values: 0.6-1.2 mg/dL for males; 0.5-1.1 mg/dL for females. Abnormally high amounts: suggest glomerulonephritis, pyelonephritis, urinary tract obstruction, shock, dehydration, or congestive heart failure (CHF). Deficiency: suggests debilitation, muscular dystrophy, or myasthenia gravis.
How To Interpret Complete Blood Count (CBC) Values
A
Red Blood Count (RBC) Test.
This test is typically used to screen patients for anemia. Normal laboratory values: 4.7-6.1 cells/mcL for males; 4.2-5.4 cells/mcL for females Abnormally high amounts: suggest high altitude, congenital heart disease, or dehydration. Deficiency: suggests anemia, hemorrhage, hemolysis, or leukemia.
Hemoglobin (Hgb) Test.
It reflects the number of red blood cells in the blood. Normal laboratory values: 14-18 g/dL for males; 12-16 g/dL for females. Abnormally high amounts: suggest congenital heart disease, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), high altitudes, or dehydration. Deficiency: suggests anemia, hemorrhage, hemolysis, or nutritional deficiency,
Hematocrit (Hct) Test.
It refers to the proportion of red blood cells to the fluid component called plasma. It is commonly used to diagnose anemia. Normal laboratory values: 42-52% for males; 37-47% for females Abnormally high amounts: suggest congenital heart disease, severe dehydration, or eclampsia. Deficiency: suggests anemia, hyperthyroidism, cirrhosis, hemolytic reactions, or hemorrhage.
White Blood Cell (WBC) Test.
It may be carried out to detect the presence of an infection. Normal laboratory values: 5,000-10,000/mcL Abnormally high amounts: suggest infection, leukemic neoplasia, trauma, stress, or Inflammation. Deficiency: suggests drug toxicity, bone marrow failure, or infection.
Platelet (Plt) Count Test.
It is a test administered to measure the number of platelets in the blood. Normal laboratory values: 150,000-400,000/mcL Abnormally high amounts: suggest malignant disorder, rheumatoid arthritis, or iron deficiency anemia. Deficiency: suggests hypersplenism, hemorrhage, immune thrombocytopenia, or leukemia.
How To Interpret Coagulation Test Values
Coagulation tests are blood tests that evaluate the function of one or more coagulation factors.
Prothrombin Time (PT).
It measures the ability of coagulation factors I, II, V, VII, and X. Normal laboratory values:11-12.5 seconds Abnormally long duration: suggests cirrhosis,
hepatitis, vitamin K deficiency, hereditary factor deficiency, or disseminated intravascular coagulation (DIC). Abnormally short duration: suggests an increased risk for blood clots.International Normalized Ratio (INR).
It measures the time for the blood to clot. Normal laboratory values: 0.8-1.1 seconds Abnormally long duration: suggests that the patient’s blood is too thin, and has an increased risk for bleeding, or is on warfarin (Coumadin) therapy. Abnormally short duration: suggests that the patient’s blood is not thin enough while on warfarin therapy.
Partial Thromboplastin Time (PTT).
It is used to measure the clot formation pathway and monitor the thinning of the blood during heparin therapy. In an activated partial thromboplastin time (aPTT), an activator is added to speed up clotting time. Normal laboratory values: 60-70 seconds Activated Partial thromboplastin time (aPTT): 30-40 seconds Abnormally long duration: suggests disseminated intravascular coagulation (DIC), hemophilia, liver cirrhosis, vitamin K deficiency, or heparin administration. Abnormally short duration: suggests early stages of DIC or extensive cancer.
D-dimer.
It is a test to confirm if the patient has a blood clotting disorder, such as pulmonary embolism (PE) and deep vein thrombosis (DVT). Normal laboratory values: <250 ng/mL
Validity of Laboratory Values
Healthcare providers should note that lab test results are not definitive diagnoses, and several situations may influence laboratory values. For instance, if the patient is healthy, yet the generated laboratory values suggest otherwise, it may not be a cause for concern. Due diligence is also required to avoid errors in diagnoses.
Final Thoughts
Laboratory values play a significant role in diagnosing and monitoring a patient’s condition. They help medical professionals assess which possible treatments and maintenance measures are necessary to ensure the optimum health of their patients. It is essential to practice due diligence in obtaining these values to prevent mistakes that might endanger patients’ lives.