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Kidney Week

Abstract: SA-PO165

Free Vitamin D Is Independently Associated with Mean Arterial Blood Pressure in Diabetic Patients with Impaired Kidney Function

Session Information

Category: Diabetic Kidney Disease

  • 602 Diabetic Kidney Disease: Clinical

Authors

  • Bachert, Daniela Stephanie, Dialysiscenter Potsdam /Institute for Nutritional Science, University of Potsdam, Potsdam, Germany, Potsdam, Germany
  • Pavkovic, Mira, Bayer AG, Pharmaceuticals, Wuppertal, Germany
  • Sandner, Peter, Bayer AG, Pharmaceuticals, Wuppertal, Germany
  • Zeng, Shufei, Charité University Berlin, Berlin, Germany
  • Hocher, Carl-Friedrich, Charles University, Prague, Prague, Czechia
  • Tsuprykov, Oleg, University of Potsdam, Potsdam, Germany
  • Elitok, Saban, Klinikum Ernst von Bergmann, Potsdam, Germany
  • Hocher, Berthold, University of Potsdam, Potsdam, Germany

Group or Team Name

  • Charité University Berlin
Background

Blood pressure control is key for the prevention of complications of diabetes such as CKD progression. Vitamin D is thought to play a role in blood pressure regulation in diabetic patients. Total 25-hydroxyvitamin D are currently routinely used in clinical practice to assess vitamin D status. In the circulation, vitamin D – like other steroid hormones – is bound to a special carrier – vitamin D-binding protein (DBP). Only very tiny amounts of the total vitamin D are free and potentially biologically active, because only free vitamin D interact with the vitamin D receptor. The aim of the study was to compare the association of free and total vitamin D with blood pressure in diabetic patients with impaired kidney function.

Methods

Free and total vitamin D concentration were measured in 225 diabetic patients with impaired kidney function. Mean arterial blood pressure (MAP) was calculated based on 3 independent ambulatory blood pressure measurements and was 93.1 +/- 11.0 mmHg. Patients received cholecalciferol if needed. The cholecalciferol dose was adjusted after total vitamin D measurements every 3 months to meet vitamin D serum targets as defined by the German Society of Nutritional Medicine. Multiple linear regression analysis considering age, sex, BMI, eGFR, family history of hypertension, treatment with antihypertensive drugs and diuretics as confounding factors.

Results

This study revealed that free vitamin D was independently associated with MAP (p=0.026, CI: -1.285 – -0.049) whereas total vitamin D was not associated with MAP (p=0.308; CI: - 0.285 – 0.091).

Conclusion

Free – but not total - vitamin D serum concentrations in patients with diabetes and impaired kidney function are interdependently invers correlated with blood pressure, a key disease progression factor. This study suggests that free vitamin D measurements might be a better clinical tool – as compared to measurements of total vitamin D - to adjust vitamin D therapy in diabetic patients with impaired kidney function. However, reference values and treatment targets for free vitamin D in diabetic patients with impaired kidney disease have to be established.