Serum Vitamin D levels
|Why is this test done?||This test is used to determine hydroxy-vitamin D levels in the blood. Vitamin D measurements are mainly performed to ascertain whether there is a deficiency.|
|How to prepare:||
|Associated Tests:||In some cases, total calcium is ordered at the same time as the serum vitamin D test.|
This test should be performed on those 50 years of age and older at increased risk for vitamin D deficiency. It should also be ordered when undergoing therapy for osteoporosis. A second measurement should be taken 3-4 months after vitamin D supplementation has been initiated to reassess concentrations. Once the optimal level of vitamin D is reached, no additional measurements are required.
What does an abnormal test result mean?
If the result is too high
Sarcoidosis and some types of lymphoma may cause excess amounts of vitamin D. Elevated vitamin D serum concentrations are often accompanied by hypercalcemia. Hyperparathyroidism, vitamin D toxicity and type-II vitamin D-dependent rickets may also cause high levels of vitamin D.
If the result is too low
Vitamin D levels below target values may be indicative of a dietary vitamin D deficiency. However, hypoparathyroidism, pseudohypoparathyroidism, malignant hypercalcemia, renal insufficiency, hyperphosphatemia, hypomagnesemia and type-1 vitamin D-dependent rickets can also cause results to be lower.
What you need to know before the test
Before going for blood tests, a procedure or other exam, it is best to always bring a list of all the drugs you take (prescription, OTC and natural health products). Unless told otherwise, you should take your medication as usual on the day of the test. When in doubt, ask your pharmacist for more information.
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.