No guesswork... butTest nokara D aduda kiyala guess karanna vidi nadda?
There are Rapid Tests which can be done at home. Sadly not available in SL but the cost of these range from 20 USD to in excess of 300USD per kit. The cost depends on the accuracy of the assay but the $20 one is good enough.
Note : Vitamin D exists in two forms. Much of vitamin D in the blood is bound to carrier proteins, but thete's a small fraction of “free,” unbound Vitamin D as well. Though this amounts to about 0.04% , it's still considered significant. Some special lab assays are able to meaure both.