2.3. Analytical Parameters
Vitamin D status was assessed by measuring the sum of 25(OH)D2 and 25(OH)D3 serum concentrations, hereafter referred to as total 25(OH)D. The total 25(OH)D was quantified from 20 μL Mitra tips using volumetric absorptive microsampling technology (VAMSCapillary blood samples were collected through a finger prick using Microlet