The test used is 25-hydroxy vitamin D, the storage form that best reflects your overall status over recent weeks.
Indoor work patterns, sun protection, air quality and dietary habits all contribute to the low values commonly reported across urban India.
Symptoms discussed alongside low vitamin D include fatigue, muscle aches and bone discomfort, but these are non-specific and can have many other causes.
Supplementation dose and duration should always be decided by a doctor, and a repeat test is usually advised after a treatment course rather than during it.