LB020 - CORRELATION BETWEEN SERUM AND URINARY VITAMIN D METABOLITES USING LC-MS/MS

LB020

CORRELATION BETWEEN SERUM AND URINARY VITAMIN D METABOLITES USING LC-MS/MS

S. Wu^1,2,*, N. Ishimine², K. Takahashi³, M. Takiwaki³, K. Abe³

¹Health and Medical Science Unit, Health Science Division, Department of Medical Sciences, Shinshu University, ²Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, ³ME Business Operations, JEOL Ltd., Tokyo, Japan

Rationale: Vitamin D (VD) is involved in bone health, immunity, cardiovascular function, and cancer prevention. Recent studies suggest that 24,25-dihydroxyvitamin D₃ (24,25[OH]₂D₃) and the VD metabolite ratio (VMR = [24,25(OH)₂D₃ / 25(OH)D] × 100) may serve as indicators of VD levels. Assessment of VD levels relies on serum measurements. This study investigated the utility of urinary VD metabolites as a non-invasive alternative and whether they can serve as surrogate markers for serum VD metabolites.

Methods: We used residual serum and urine from the annual health checkup of employees at Shinshu University Hospital, Japan. Urine samples were mixed with

β-glucuronidase. Both serum and urine were processed via solid-phase extraction, followed by DAP-PA derivatization (JeoQuant^TM VD kit [JEOL, Japan]). LC-MS/MS was used to quantify serum and urinary 25(OH)D₃, 25(OH)D₂, 3-epi-25(OH)D₃, 24,25(OH)₂D₃, and urinary 23,25(OH)₂D₃. Serum whole parathyroid hormone (PTH) levels were measured using an electrochemiluminescence immunoassay, and urinary VD metabolites were adjusted for urinary creatinine. Correlations were assessed using Spearman’s rank correlation coefficient.

Results: A total of 506 participants (156 males, 350 females; median age 41 [IQR 33–51]) were included. Urinary 25(OH)D (25[OH]D₃ + 25[OH]D₂); 24,25(OH)₂D₃; and VMR were well-correlated with the corresponding serum markers (ρ = 0.61, 0.84, and 0.49, respectively; all p < 0.001). Serum 24,25(OH)₂D₃ and VMR, and urinary 24,25(OH)₂D₃, 23,25(OH)₂D₃, and VMR were inversely correlated with whole PTH (ρ = -0.24 to -0.31; p < 0.001), whereas serum and urinary 25(OH)D were weakly correlated (ρ = -0.17, p < 0.001, ρ = -0.071, p = 0.11, respectively).

Conclusion: We found a correlation between urinary VD metabolites, particularly 24,25(OH)₂D₃ and VMR, with serum values and PTH, suggesting their potential use as non-invasive markers for VD status.

Disclosure of Interest: S. Wu Grant / Research Support from: This study was conducted as a collaborative research project with JEOL Ltd., which provided financial support and research materials., N. Ishimine Grant / Research Support from: This study was conducted as a collaborative research project with JEOL Ltd., which provided financial support and research materials., K. Takahashi Grant / Research Support from: This study was conducted as a collaborative research project with JEOL Ltd., which provided financial support and research materials., M. Takiwaki Grant / Research Support from: This study was conducted as a collaborative research project with JEOL Ltd., which provided financial support and research materials., K. Abe Grant / Research Support from: This study was conducted as a collaborative research project with JEOL Ltd., which provided financial support and research materials.