Vitamin D

Author: Lynne Brodeur, MA, MLS(ASCP)CM
Reviewers: Kevin F. Foley, PhD, DABCC, MT, SC and Joshua J. Cannon, MS, MLS(ASCP)CMSHCM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 1 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Clinical Chemistry/UA/Toxicology): 1 hour(s)

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This course discusses the role of Vitamin D in the human body and helps differentiate between the various forms of vitamin D. The mechanisms of metabolism of vitamin D are presented along with the role of the laboratory in the testing for vitamin D. The analytical variables that may affect vitamin D testing are also discussed in this course.

Objectives

  • Differentiate between the various forms of vitamin D.
  • Explain the mechanisms of metabolism of vitamin D.
  • Discuss vitamin D deficiency, screening, and risk factors.
  • List the various methodologies for testing vitamin D.
  • List the analytical variables that may affect vitamin D testing.

Course Outline

  • The Different Forms of Vitamin D
    • Role of Vitamin D
    • Receptors
    • Vitamin D Forms
    • Vitamin D2 Forms
    • Vitamin D3 Forms
    • Vitamin D is considered biologically inactive until it undergoes two enzymatic hydroxylation reactions. Where do these reactions take place?
    • The active form of vitamin D is called:
  • Vitamin D Sources and Metabolism
    • Sources
    • Metabolism
    • Absorption and Excretion
    • Recommended Daily Intake of Vitamin D
    • According to the National Academy of Medicine (NAM), what is the recommended dietary allowance of vitamin D for a 65-year-old person?
    • How much vitamin D is absorbed depends upon the presence of what substance?
  • Causes of Vitamin D Deficiency
    • Decreased Intake
    • Sunlight and Skin Pigmentation
    • Sunscreen
    • Age
    • Absorption Issues
    • Renal Disease
    • Which one of these patients is most likely to be deficient in vitamin D?
    • Which of the following factors could result in a decrease in vitamin D?
  • Diseases Associated with Decreased Vitamin D
    • Children (Growth and Development)
    • Hyperparathyroidism
    • Osteoporosis and Osteopenia
    • Immune System Impairment
    • Rickets
    • True or False: Vitamin D is not responsible for building strong bones and teeth in children.
    • Dorothy is a 70-year-old female with the following test results:Vitamin D = 9 ng/mL (20–50 ng/mL)Calcium = 7.0 mg/dL (8.5–10 mg/dL)Based on these values (normal ranges in parenthesis), predict the result of the parathyroid hormone (PTH).
  • Vitamin D Testing Methods and Methodologies
    • Historical Measurements
    • The Reference Method
    • HPLC (High-performance liquid chromatography)
    • Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
    • Immunoassays
    • Sample Requirements
    • Which types of samples would be most appropriate for vitamin D testing?
    • What are some advantages of using liquid chromatography-tandem mass spectrometry (LC-MS/MS) versus traditional immunoassay techniques?
  • Interferences
    • Medications
    • Antibody and Other Interferences
    • True or False: Heterophile antibodies may cause erroneous results in assays that utilize antibodies as their methodology.
    • A patient from the dialysis unit has a vitamin D ordered along with BUN and creatinine. The laboratory request form that accompanies this sample states that the patient has received the drug Paricalcitol (Zemplar) within the past 12 hours. Should you continue with the testing of this sample?
  • References
    • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical laboratory technicians, laboratory supervisors, and laboratory managers. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Lynne Brodeur, MA, MLS(ASCP)CM holds a master of arts degree in teaching. She is currently a full time lecturer at the University of Massachusetts Dartmouth and works per diem in Clinical Chemistry at St. Luke's Hospital in New Bedford, MA.
Reviewer Information:
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.
Joshua J. Cannon, MS, MLS(ASCP)CMSHCM received his Bachelor of Science and Master of Science in Medical Laboratory Science from Thomas Jefferson University in Philadelphia, PA. He holds Medical Laboratory Scientist and Specialist in Hematology certifications through the ASCP Board of Certification. He was a professor at Thomas Jefferson University for seven years before transitioning into his current role as Education Developer at MediaLab. His areas of expertise and professional passions include clinical hematology and interprofessional education.