Vitamin D: When Testing May Be Necessary

Before delving deeper into who should be getting their vitamin D level checked, first let’s talk about vitamin D’s role in the body.  

Vitamin D is necessary for bone health so that calcium and phosphorus can be used to build new bones. You may have heard of Rickets; this is a disorder that causes bones to be soft and weak in children due to a deficiency of vitamin D. 

Vitamin D is unique in that it can be obtained orally, or most people’s bodies can create it from direct sunlight on the skin when outdoors. It is a fat-soluble vitamin, which means it does not dissolve in water and is absorbed best when taken with fat-containing foods. This also means it is possible to overdose on supplements of vitamin D, but not from dietary intake or sunlight exposure.

Certain medical conditions are known to cause vitamin D deficiency and people with these conditions should have their vitamin D levels checked:

Cystic fibrosis, Crohn’s disease, celiac disease, and individuals who have undergone weight loss surgeries often have altered absorption of vitamin D.  

Kidney and liver diseases reduce these organs’ ability to convert vitamin D into its active hormone form, Calcitriol, resulting in a deficiency.  

Dysfunction of the parathyroid gland will also cause vitamin D deficiency due to the parathyroid role in maintaining blood levels of calcium.  

Individuals with multiple sclerosis (MS) are recommended to maintain higher than average vitamin D levels and may need more frequent monitoring and more intense supplementation than others. Research has actually shown that maintaining normal levels of vitamin D may have a protective effect and lower the risk of developing MS.  

Individuals who are obese, which is anyone with a body mass index of 30 or above.

What are possible symptoms of vitamin D deficiency?

Muscle aches, weakness, pain, and/or cramping. Painful bones. Difficulty thinking clearly or remembering things. Mental health changes including depression and frequent mood swings. Fatigue. Changes in sleep include poorer sleep quality and reduced sleep duration. Also, reduced endurance. Excessive sweating on the head. Hair that is thin, brittle, or excessive hair loss. Wounds that heal slowly or recurring infections. Dizziness. High blood pressure, heart disease, or stroke. Weight gain. 

Studies show that vitamin D deficiency is prevalent, affecting about 42% of the population of the United States, but is variable depending on the time of year. 

Since we can synthesize vitamin D from sunlight exposure, fewer people are deficient during months with more daylight hours than during winter. As we age our risk of vitamin D deficiency also increases due to multiple factors.

Anyone with a medical condition known to affect vitamin D levels should have an assessment performed. But, for everyone else there are no clinical guidelines that are set in stone. 

Therefore, if you are suspicious that you are vitamin D deficient because you:

• do not spend at least 20 minutes in direct sunlight at least four days per week 

• do not eat a diet with sufficient vitamin D intake 

• and/or have symptoms mentioned above, then discuss with your medical provider if you should have a level checked. 

Or increase your dietary intake of vitamin D and/or increase your direct sun exposure and keep a log of your symptoms and see if the increased vitamin D intake decreases your symptoms.

Obesity and vitamin D deficiency have a complicated relationship, which I discuss in the article here: Obesity and Vitamin D Deficiency- Correlation vs. Causation.