Comparison of 4 groups of patients who did another 25(OH)D test at ∼1 year after the first one.

Sufficient-to-sufficient, patients with sufficient VD results from both tests; sufficient-to-low, patients with sufficient results from the first test but abnormally low results (VD-insufficient or deficient) from the second; low-to-sufficient, patients with abnormally low results from the first test but sufficient results from the second one; low-to-low, patients with abnormally low results from both tests. Statistical analysis was performed to assess the significance of the differences between the sufficient-to-sufficient and sufficient-to-low groups, and between the low-to-sufficient and low-to-low groups.*p**p***p