People can do vitamin D monitoring at home. See above link to www.grassrootshealth.net. They will sell you 2 test kits for serum D3 for $50 (I think). You take

People can do vitamin D monitoring at home. See above link to www.grassrootshealth.net. They will sell you 2 test kits for serum D3 for $50 (I think). You take the tests 6 months apart, and they send you the results each time, so you can test the efficacy of whatever you are changing (i.e. sun exposure). I was 39ng at my first test, near mid-range and not deficient, and decided to bump up my sun exposure a bit just in case, and never bothered with the second test. I live in a sunny area, fortunately.