INTRODUCTION: Vitamin D has been associated with extra-skeletal pathologies through mechanisms involving inflammatory and oxidative stress processes. Ischemia-modified albumin (IMA) is one of the earliest indicators of ischemia, and is regarded as a marker of oxidative stress. In the present study, the IMA level in serum samples with various 25-OH vitamin D [25(OH)D] concentrations was examined for signs of oxidative stress as a result of vitamin D deficiency.
METHODS: A total of 80 serum samples requested by clinicians for 25(OH)D testing and analysis were randomly selected and divided into 4 groups (n=20 in each group) according to the 25(OH)D concentration. Group 1: ≤10 ng/mL (severe deficiency), Group 2: 10-20 ng/mL (deficiency), Group 3: 20-30 ng/mL (insufficiency), and Group 4: ≥30 ng/mL (sufficiency) were formed. Serum IMA was measured spectrophotometrically, and the results were expressed in absorbance units (ABSU).
RESULTS: The IMA level in Group 1 through Group 4 was 0.541±0.082 ABSU, 0.515±0.059 ABSU, 0.438±0.085 ABSU, and 0.467±0.102 ABSU, respectively. The IMA level was found to be significantly different in comparisons between Groups 1 and 3, Groups 1 and 4 and Groups 2 and 3 (p=0.001, p=0.032, p=0.022, respectively); no significant difference was found in other comparisons of the groups. There was a weak negative correlation between serum 25(OH)D and IMA level (r= -0.346; p=0.002).
DISCUSSION AND CONCLUSION: The serum IMA level is elevated in severe vitamin D deficiency and vitamin D insufficiency due to increased oxidative stress resulting from the inadequate antioxidant function of vitamin D. The IMA level may have been higher in the vitamin D sufficiency group compared with the insufficiency group due to a possible pro-oxidant effect of vitamin D as its level rises. If this hypothesis is confirmed with future studies, it may be appropriate to consider a serum 25(OH)D level of between 20 and 30 ng/mL sufficient.