Test to Diagnose Vitamin D Deficiency
Find out if you are low in Vitamin D?
You may or may not have any symptoms due to Vitamin D deficiency. The best approach is to get your vitamin D level checked. It's a simple blood test. However, it's very important to get the correct test for Vitamin D.
There are two tests for vitamin D level:
25 OH Vitamin D and 1,25 OH Vitamin D.
25 OH Vitamin D (and NOT the 1,25 OH Vitamin D) is the correct test for diagnosing Vitamin D deficiency.
Range of 25 OH Vitamin D level:
Another common problem is the normal range provided by the lab that comes with the results. In my experience, most normal ranges provided by the lab are incorrect.
A 25 OH vitamin D level less than 30 ng/ml (or 75 nmol/L) is considered low by most endocrinologists.
The normal range of 25 OH vitamin D should be 30-100 ng/ml which is equal to 75-250 nmol/L.
How to Convert Vitamin D level in nmol/L into ng/ml?
The conversion factor is 2.5
nmol/L divided by 2.5 = ng/ml
For example, a 25 OH vitamin D level of 50 nmol/L divided by 2.5 = 20 ng/ml
This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, Endocrinology and Metabolism.
Dr. Zaidi is a former Assistant Clinical Professor of Medicine at UCLA. Currently he is Medical Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.
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