CAP Pro Course - Chemistry - Laboratory Evaluation of Serum/Plasma Electrolytes and Acid-Base Balance

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Author: Kevin F. Foley, PhD, DABCC, MT, SC, TC(NRCC)
Reviewers: Alec Saitman, PhD; DeRhonda Crawford, MT(ASCP)

Continuing Education Credits

Objectives

  • List and describe the major electrolytes, their functions, and how they are regulated.
  • Describe the mechanisms for controlling acid-base balance in the body and identify disorders associated with acid-base base imbalance.
  • Define anion gap in relation to measured and unmeasured cations and measured and unmeasured anions.
  • Discuss conditions associated with low and high anion gap and the importance of anion gap in the differential diagnosis of metabolic acidosis.

Course Outline

  • List and describe the major electrolytes, their functions, associated conditions, and how they are regulated.
      • Serum Electrolytes
      • Serum Electrolytes, continued
      • Sodium (Na+)
      • Hyponatremia
      • Hypernatremia
      • Potassium (K+)
      • Hypokalemia
      • Hyperkalemia
      • Chloride (Cl-)
      • Hypochloremia and Hyperchloremia
      • Calcium (Ca)
      • Ionized Calcium
      • Bicarbonate (HCO3–)
      • Bicarbonate, continued
      • Decreased HCO3– (Metabolic Acidosis)
      • Increased HCO3– (Metabolic Alkalosis)
      • Measurement of Electrolytes
      • Testing Methodologies
      • Testing Methodologies, continued
      • Assessment Checks for Validity
      • A medical laboratory scientist observes a critically high K level of 6.2. Which of the following is least likely?
      • A physician orders a bicarbonate level on a patient who has ingested an excessive amount of 'heartburn tablets.' They have a blood pH of 7.49. Which f...
      • A laboratorian is asked why the total CO2 value for a specimen is higher than the bicarbonate concentration for the specimen. Which of the following i...
      • Which of the following statements is not true?
      • A sample arrives in the laboratory with an order for an electrolyte panel (Na, Cl, K, HCO3-). The medical laboratory scientist notes that the sample i...
      • A laboratorian noticed that a patient who has recurring low results for serum Na recently had an elevated result for serum copeptin (performed at an o...
      • A medical laboratory scientist has an order for whole blood ionized calcium (iCa) and pH. The sample was uncapped and left to sit before testing. This...
      • A patient with laboratory results shows persistently low potassium levels. Which of the following hormones would most likely be elevated in response?
  • Describe the mechanisms for controlling acid-base balance in the body and identify disorders associated with acid-base imbalance.
      • Acid-Base Balance
      • Acid-Base Balance, continued
      • Regulation of Acid-Base Balance
      • Buffer Systems
      • Bicarbonate Buffer System
      • Respiratory Regulation of Acid-Base Balance
      • Renal Regulation of Acid-Base Balance
      • Acid-Base Disorders
      • Respiratory Acidosis and Respiratory Alkalosis
      • Metabolic Acidosis and Metabolic Alkalosis
      • Compensation Mechanisms
      • Metabolic Compensation
      • Measurement of Acid-Base Balance Parameters
      • Measurement of Acid-Base Balance Parameters, continued
      • Ion Selective Electrodes Used for the Measurement of Arterial Blood Gas Parameters
      • To raise blood pH, which of the following can occur?
      • A patient has metabolic alkalosis with respiratory compensation. Which of the following will not be true in this patient?
      • A respiratory therapist (RT) brings a blood gas sample to the laboratory for testing. The RT states that the sample is from a patient whose ventilator...
      • A patient diagnosed with a Clostridioides difficile infection has been having serial blood pH measurements taken. The pH values have been abnormal as ...
      • A sample has a pH of 7.51 and bicarbonate concentration of 34 mEq/L (Ref Range: 22 - 28 mEq/L). Which condition would be consistent with these finding...
      • The main buffer system in blood is the bicarbonate/carbonic acid system. To maintain a normal pH of around 7.4, the bicarbonate to carbonic acid ratio...
      • A laboratory receives specimens for a patient with compensated respiratory acidosis. Which of the following would most likely be true?
  • Define anion gap in relation to measured and unmeasured cations and measured and unmeasured anions. Discuss conditions associated with low and high anion gap and the importance of anion gap in the differential diagnosis of metabolic acidosis.
      • Anion Gap
      • Anion Gap, continued
      • Anion Gap, continued
      • Increased Anion Gap
      • Decreased Anion Gap
      • Laboratory Error
      • Use of Anion Gap for Determining Causes of Metabolic Acidosis
      • Normal Anion Gap Metabolic Acidosis
      • Which of the following is included in anion gap calculations?
      • A medical laboratory scientist performing electrolyte panel testing notices that several patients have decreased anion gaps (values consistently below...
      • A medical laboratory scientist runs an electrolyte panel on a patient with the following results:Na: 139 mEq/LCl: 100 mEq/L HCO3-: 22 mEq/LK: 6 mEq/LW...
      • Which of the following is definitely true in a patient with an anion gap of 23?
      • A medical laboratory scientist receives a sample from an inpatient that has a calculated anion gap of 18. Which of the following is least likely?
      • Which of the following anions is a measured anion used in the anion gap equation?
      • A patient with a high anion gap and metabolic acidosis is being cared for in your hospital. Follow-up laboratory testing is being ordered. Which of th...
      • Which of the following conditions results in acidosis with a normal anion gap?
  • References
      • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: This program is designed as an educational and training tool for MLS, MT, and MLT personnel, medical laboratory science students and interns, pathology residents, and practicing pathologists.
Author: Kevin F. Foley, PhD, DABCC, MT, SC is the director of clinical pathology for the Kaiser Permanente Northwest region. He also teaches clinical chemistry at Oregon Health Sciences University. Dr. Foley earned his PhD in clinical pharmacology and toxicology at East Carolina School of Medicine in North Carolina.
Reviewer Information: 
Dr. Alec Saitman received his Ph.D. in Organic Chemistry at the University of California, San Diego where he focused his research on the total synthesis of marine natural products. He completed his fellowship training in clinical chemistry and toxicology in the Department of Pathology at the University of California, San Diego under the guidance of Dr. Robert Fitzgerald. Alec’s current focus in on clinical mass spectrometry method development for the quantitative analysis of small molecules in patient specimens.
DeRhonda Crawford, MT(ASCP) is the chemistry supervisor at Gwinnett Medical Center in Lawrenceville, Georgia and the technical supervisor for the Gwinnett Medical Center in Duluth, Georgia. She holds a BS in Medical Technology from the Medical College of Georgia.

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