Vitamin D levels can fluctuate for several reasons related to sunlight exposure, diet, health conditions, and medication use. Low levels (deficiency) are often linked to limited time in the sun, low intake of vitamin D–rich foods, or conditions that reduce absorption, such as certain digestive disorders. Chronic kidney or liver disease, obesity, and medications like glucocorticoids, anticonvulsants, or some HIV treatments can also lower vitamin D.
Conversely, high levels (excess) are less common but may result from taking too many supplements, consuming large amounts of fortified foods, or from rare medical conditions such as sarcoidosis or lymphoma, which can increase the body’s production of active vitamin D.
Yes. Some at-home kits use a small finger-prick sample mailed to a lab, though clinic tests are usually more precise.
Testing is generally recommended for people at risk of deficiency — including those with limited sun exposure, darker skin tones, malabsorption disorders, or chronic kidney disease.
No fasting is required, but you may be asked to skip supplements the day before.
Most labs report results within one to three business days.
If your levels are normal and you don’t have risk factors, testing every few years is enough. People taking supplements or experiencing chronic illness may need checks every 6–12 months.
Usually, yes, when ordered for a medical reason such as bone disease or deficiency symptoms. However, insurance is not required for lab testing through Hers.
An untreated deficiency can weaken bones (osteomalacia or osteoporosis), raise fracture risk, and cause muscle weakness or fatigue.
It depends on location, skin tone, and time spent outdoors. Many people in northern climates or with darker skin require supplements or fortified foods.
• Calcium and phosphorus tests
• Parathyroid hormone (PTH) test
• Comprehensive metabolic panel (CMP)
• Bone density (DEXA) scan
• Kidney and liver function tests
