I would caution against use of this site. Although, granted the developers are respected clinicians and researchers - from the Laboratory for Quantitative Research at Massachusetts General Hospital (MGH) - nonetheless there is no revelation as to the underlying methodology of the calculators in terms of which of many divergent studies and trials are the founding ones for various computation, and more critically, unlike the Gail Model, Adjuvant! Online and Oncotype DX, no assessments from any of the risk, prognosis and outcome calculators have ever been subjected to peer-reviewed published independent validation under standard rigorous requirements, and without this any derivations are without requisite and reproducible verification, and hence unvalidated.
As to your Vitamin D levels from the 25-Hydroxy Vitamin D assay, it can take several weeks before internal levels fully respond; a rule of thumb is approximately no less than 6 weeks, so you should retest after another several weeks to be sure of reasonable uptake time.
If upon retest, levels are still significantly below 52ng/ml, one more retest should be conducted after increasing the dose. Here one suggestion is to alternate 4000 IUs on one day with 8000 on the following day, and this would average to approx. 5700 IU daily over the course of one week, about a 42% increase over your present dose level (4000 IUs). Based on the math of 25(OH)D, this should theoretically raise your level to at least 48 ng/ml. If it does not, there may be a problem of calcium utilization, in which case a high bioavailability / high utilization calcium preparation like Cal-Quick (Twinlab) should be tried, taken only with meals (towards the end of a meal).
However, the next reading (after dose increase) should give some clues as to what's going on, as we expect 25(OH)D levels to rise by about 10 ng/ml points for each increase of 1000 IUs, at least in the typical case (and dosing up to 10,000 IUs is still known to be safe if needed), and the alternating regimen is assured to provide at least 1700 additional IUs on an average daily so we'd be expecting numbers in the high 40's or above at the reading after dose increase.
Breast Cancer Watch