The Effect of the Systemic Inflammatory Response on Plasma Vitamin 25 (OH) D Concentrations Adjusted for Albumin

BACKGROUND: Plasma 25-hydroxyvitamin D (25(OH) D) deficiencies are associated with several diseases. The magnitude of systemic inflammatory response, as evidenced by C-reactive protein (CRP), is a major factor associated with lower 25(OH)D. Other aspects of the systemic inflammatory response may be important in determining plasma 25 (OH)D concentrations. AIM: To examine the relationship between plasma 25(OH)D, CRP and albumin concentrations in two patient cohorts. METHODS: 5327 patients referred for nutritional assessment and 117 patients with critical illness were examined. Plasma 25 (OH) D concentrations were measured using standard methods. Intra and between assay imprecision was <10%. RESULT: In the large cohort, plasma 25 (OH) D was significantly associated with CRP (r(s) = -0.113, p<0.001) and albumin (rs = 0.192, p<0.001). 3711 patients had CRP concentrations ≤ 10 mg/L; with decreasing albumin concentrations ≥ 35, 25-34 and <25 g/l, median concentrations of 25 (OH) D were significantly lower from 35 to 28 to 14 nmol/l (p<0.001). This decrease was significant when albumin concentrations were reduced between 25-34 g/L (p<0.001) and when albumin <25 g/L (p<0.001). 1271 patients had CRP concentrations between 11-80 mg/L; with decreasing albumin concentrations ≥ 35, 25-34 and <25 g/l, median concentrations of 25 (OH) D were significantly lower from 31 to 24 to 19 nmol/l (p<0.001). This decrease was significant when albumin concentration were 25-34 g/L (p<0.001) and when albumin <25 g/L (p<0.001). 345 patients had CRP concentrations >80 mg/L; with decreasing albumin concentrations ≥ 35, 25-34 and <25 g/l, median concentrations of 25 (OH) D were not significantly altered varying from 19 to 23 to 23 nmol/l. Similar relationships were also obtained in the cohort of patients with critical illness. CONCLUSION: Plasma concentrations of 25(OH) D were independently associated with both CRP and albumin and consistent with the systemic inflammatory response as a major confounding factor in determining vitamin D status.