Upon completion of the chapter and exercises, the student pharmacist will be able to
Recognize normal ranges for common laboratory values in adults.
Identify common causes for abnormal laboratory values.
List circumstances that may produce false-negative or false-positive laboratory results.
Interpret the clinical significance of abnormal laboratory values.
Utilize clinical laboratory data to monitor various disease states.
You are rounding on an internal medicine advanced pharmacy practice experience with the ICU team. When preparing for rounds, note that there was a new admission last night—an Olympic bicyclist who was struck by a car. Begin reviewing the patient's laboratory data in preparation for rounds.
On admission to the hospital last night, patient X had the following CBC:
- WBC: 7,200 cells/mm3
- RBC: 3.7 × 106 cells/mm3
- Hgb: 10 g/dL
- Hct: 30%
- MCV: 92 μm3/cell
- MCH: 30 pg/cell
- MCHC: 35 g/dL
Discussion Questions—Part 1:
- What do the above abbreviations represent?
- Which of the laboratory values are abnormal?
- What type of anemia is present?
- What is the most likely cause of the anemia in this patient?
- In addition to the CBC, what other laboratory tests were most likely ordered for this patient upon admission to the hospital?
- What abnormalities (if any) would you expect to see on these laboratory tests?
Several days later the patient begins to spike fevers. A CBC, chest x-ray, UA, and blood and urine cultures are done to look for possible sources of infection. The CBC and UA results are as follows:
- CBC with differential
- WBC: 17,900 cells/mm3
- WBC differential
- -Segs: 65%
- -Bands: 10%
- -Lymphocytes: 17%
- -Monocytes: 5%
- -Eosinophils: 2%
- -Basophils: 0.5 %
- RBC: 4.2 × 106 cells/mm3
- Hgb: 14 g/dL
- Hct: 42%
- MCV: 90 μm3/cell
- MCH: 31 pg/cell
- MCHC: 36 g/dL
- Urine color: straw, cloudy
- SG: 1.010
- pH: 7.2
- Protein: trace
- Glucose: negative
- Ketones: negative
- Blood: trace
- Bilirubin: zero
- Leukocyte esterase: positive
- Nitrites: positive
Discussion Questions—Part 2:
- What abnormalities are noted in the CBC?
- What is a "left shift," and what does it indicate? Is a left shift present?
- What abnormalities are noted on the UA?
- What is the most likely cause of these abnormalities?
- What follow-up actions/treatments will probably be needed as a result of these abnormal laboratory tests?
This chapter is designed to provide an overview of common laboratory tests used in clinical practice. The most frequently used tests such as complete blood count (CBC), electrolytes and blood chemistries, and urinalysis (UA) are provided first, followed by other clinical and diagnostic tests grouped by disease state or body system.
- Normal values may vary from laboratory to laboratory, depending on techniques and reagents used.
- Normal values may also vary depending on the patient's age, gender, weight, height, and ...