Vitamin D-Binding Protein and the Role of its Gene Polymorphisms in the Mortality of Sepsis Patients

OBJECTIVE

This study aimed to determine the role of vitamin D-binding protein (VDBP) gene polymorphisms (especially at locus rs7041), vitamin D-binding protein levels, and vitamin D levels in mortality in sepsis patients.

PATIENTS AND METHODS

We performed the analytic observational study with a case-control approach. A total of 80 patients were included in this study, 40 patients were grouped as the case group and 40 patients were grouped as the control group. The patients were diagnosed with sepsis and treated in the Intensive Care Unit (ICU), M. Djamil Hospital, Indonesia. The VDBP rs7041 gene polymorphism was analyzed using the polymerase chain reaction procedure. VDBP and vitamin D levels were examined using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The case group showed lower mean vitamin D and VDBP levels than the control group (P<0.05). There were more variations in the rs7041 gene VDBP (mutant) locus in the case group than in the control group, and this difference was considered statistically significant, P<0.05. The results of this study indicate that the occurrence of polymorphism or variations at locus rs7401 (mutant) causes a decrease in VDBP and vitamin D levels. A decrease in vitamin D levels correlates with the incidence of mortality in sepsis patients.

CONCLUSION

Polymorphism gene VDBP at locus rs7041 causes a decrease in the production of VDBP, a vitamin D carrier protein.

Characterization of vitamin D metabolism in active acromegaly in the setting of bolus (150,000 IU) cholecalciferol treatment

PURPOSE

To reveal distinctive features of vitamin D metabolism in patients with active acromegaly compared to healthy individuals, particularly in the setting of cholecalciferol treatment.

METHODS

The study group included 34 adults with active acromegaly, and the control group included 30 apparently healthy adults with similar age, sex, and BMI. All participants received a single dose (150,000 IU) of cholecalciferol aqueous solution orally. Laboratory assessments including serum vitamin D metabolites (25(OH)D₃, 25(OH)D₂, 1,25(OH)₂D₃, 3-epi-25(OH)D₃ and 24,25(OH)₂D₃), free 25(OH)D, vitamin D-binding protein (DBP) and parathyroid hormone (PTH) as well as serum and urine biochemical parameters were performed before the intake and on Days 1, 3, and 7 after the administration. All data were analyzed with nonparametric statistics.

RESULTS

Patients with acromegaly had tendency to lower baseline 25(OH)D₃ levels (p = 0.05) and lower 25(OH)D₃ levels (p < 0.05) during the follow-up. They were also characterized by PTH suppression (lower baseline PTH levels and lower prevalence of secondary hyperparathyroidism), altered production of main vitamin D metabolites (higher 1,25(OH)₂D₃ and lower 24,25(OH)₂D₃ levels with corresponding lower 25(ОН)D₃/1,25(ОН)₂D₃ and higher 25(ОН)D₃/24,25(ОН)₂D₃ ratios) as well as concordant biochemical features (higher levels of serum phosphorus and albumin-adjusted calcium levels) throughout the study (p < 0.05). The acromegaly group showed an increase in DBP levels after cholecalciferol intake as opposed to the control group (p < 0.05) and had lower increase in free 25(OH)D levels (p < 0.05). Δ25(OH)D₃ was similar between the groups (p > 0.05), showed a negative correlation with the disease activity markers-both IGF-1 levels (r = -0.44, p < 0.05) and fasting GH levels (r = -0.56, p < 0.05)-and lacked correlation with BMI in the acromegaly group (p > 0.05).

CONCLUSION

Patients with active acromegaly have dysregulated vitamin D metabolism characterized by higher 1,25(ОН)₂D₃, lower 24,25(ОН)₂D₃ and altered DBP production. The response to vitamin D supplementation in acromegaly patients might be influenced by hormonal excess. Obtained results require reproducibility check and further study to develop specific clinical recommendations.

TRIAL REGISTRATION

NCT04844164 (release date: April 9, 2021; retrospectively registered).

Unbound Vitamin D Concentrations Are Not Decreased in Critically Ill Patients

OBJECTIVE

Free concentrations of highly protein bound hormones, such as cortisol and thyroxine, are unchanged in critical illness despite substantial decreases in total concentration. Total 25-hydroxyvitamin D (25(OH)D) concentration is decreased in critical illness, but the free concentration of 25(OH)D has had less attention. The aim of this study was to compare total and calculated free 25(OH)D concentrations in critically ill patients with healthy controls.

DESIGN

Case control study.

METHODS

38 patients with critical illness were compared with 68 healthy controls. 25(OH)D was measured by liquid chromatography tandem mass spectrometry (LCMS/MS) and vitamin D binding protein (VDBP) by direct sandwich enzyme-linked immunosorbent assay (ELISA). Total and calculated free 25(OH)D concentrations were compared using unpaired T-tests.

RESULTS

Total 25(OH)D concentrations were significantly lower in critically ill patients than controls (37 (95% CI 31 - 43) vs 57 (53 - 60) nmol/L). Calculated free concentrations of 25(OH)D were not lower in critically ill patients than healthy controls (26 (22 - 29) vs 19 (18 - 20) pmol/L).

CONCLUSIONS

Calculated free 25(OH)D concentrations are not decreased in critical illness. Measuring total 25(OH)D concentrations in patients with critical illness potentially underestimates vitamin D and overestimates the number of patients who are deficient in vitamin D. This article is protected by copyright. All rights reserved.