Question 1

What's the difference between vitamin D2 and D3 on my test results?

Accepted Answer

Vitamin D3 (cholecalciferol) is the form your body makes naturally from sunlight or that you get from animal sources, while vitamin D2 (ergocalciferol) comes from plant sources or fortified foods. Both forms work similarly in your body, and the important value is your total 25-hydroxy vitamin D level. Studies have shown that vitamin D3 may raise blood levels more effectively than vitamin D2.

Question 2

How often should I test my vitamin D levels?

Accepted Answer

If you have risk factors for vitamin D deficiency, healthcare providers may recommend checking your vitamin D levels regularly to ensure they're in a healthy range. For most people, annual testing is sufficient, though those with deficiency may need more frequent monitoring during treatment. Seasonal variations can affect levels, so some individuals test twice yearly.

Question 3

Can I take vitamin D supplements if my levels are low?

Accepted Answer

Treatment for vitamin D deficiency typically involves supplements, as eating more vitamin D-rich foods usually isn't sufficient to correct deficiency. The dosage may vary depending on severity, age, weight, and whether you're pregnant or breastfeeding. Vitamin D supplements generally don't cause adverse effects at recommended doses, and it's difficult to overdose unless taking massive amounts.

Question 4

Why might my vitamin D be low even if I spend time in the sun?

Accepted Answer

Sunscreen with SPF as low as 15 reduces vitamin D production by 99.9%. People with darker skin are better protected from UV rays but need to spend longer in the sun to produce the same amount of vitamin D as those with lighter skin. Geographic location also matters: people in northern regions may not get enough vitamin D from sunlight alone, especially during colder months.

Question 5

What conditions can affect vitamin D absorption?

Accepted Answer

Several factors can cause suboptimal vitamin D levels including lack of sunshine exposure, inadequate intake, malabsorption due to conditions like celiac disease, depressed liver function, and certain medications including antiepileptic drugs like phenytoin, phenobarbital, and carbamazepine. People with GI tract diseases, those who've had bariatric surgery, and individuals with chronic kidney and liver disease are at higher risk for deficiency.

Question 6

Is this the same test as checking my active vitamin D levels?

Accepted Answer

This 25-hydroxy vitamin D test is not the same as calcitriol (1,25 di-OH Vitamin D), which must be ordered separately. Serum 25(OH)D is the barometer for vitamin D status, while serum 1,25(OH)2D provides no information about vitamin D status and is often normal or even elevated due to secondary hyperparathyroidism associated with vitamin D deficiency. The 25-hydroxy test is the preferred initial assessment.

Vitamin D (25-Hydroxy)