Effect of vitamin D on the systolic blood pressure in hypertensive
patients with low vitamine D levels.

Vitamin D insufficiency is common because of lack of sunshine exposure and too little availability of vitamin-D-rich foodsources. Low vitamin D concentrations are associated with an increased risk of
hypertension, diabetes and cardiovascular diseases, such as myocardial infarction. Suppletion of vitamin D
reduces the all-cause mortality in especially the elderly. Research in relation to low vitamin D concentrations and hypertension shows that:

1. The prevalence of hypertension increases when distance to the equator increases;

2. In winter measured blood pressures are higher;

3. Relative risk to hypertension increases strongly with 25-hydroxycholecalciferol concentrations below 37,5
nmol/l;

4. In the vitamin D insufficient, hypertensive elderly suppletion of the combination of calcium and vitamine
D shows larger decreases in systolic blood pressure and PTH than suppletion of calcium alone;

5. The plasma renin activity (PRA) increases with decreasing vitamin D concentrations.



In this double blind, randomised, placebo-controlled intervention study we want to evaluate the effect of cholecalciferol supplection on the systolic blood pressure in hypertensive patients
with a 25-hydroxycholecalciferol insufficiency. Secondly, the effects on PRC, aldosteron, 25-
hydroxycholecalciferol, alkaline phosphatase, PTH and the effect on the need of adjusting the
antihypertensive therapy are evaluated.



Only policlinical patients from Hospital Bronovo in The Hague, the Netherlands, can be included.

Does suppletion of vitamine D3 (cholecalciferol) have an effect on the systolic blood pressure in hypertensive, vitamin D insufficient patients?

1. H0 hypothesis: there is no effect on the systolic blood pressure;

2. H1 hypothesis: the systolic blood pressure decreases with at least 5 mm Hg.

1. T = 0, 6, 12 months:

A. Blood pressure;

B. Albumin;

C. For albumin corrected serum calcium;

D. Phosphate;

E. Plasma renin concentration;

F. Aldosteron;

G. 25-OH-Vitamin D;

H. 1,25-(OH)2-Vitamin D;

I. Parathyroid hormone (PTH);

J. Uric acid;

K. Alkaline phosphatase;

L. Fasting insulin;

M. Fasting glucose;

N. HbA1c;

O. CRP;

P. HsCRP;

Q. Creatinine/eGFR (MDRD);

R. Hemocytometry;

S. Triglycerides;

T. Cholesterol;

U. LDL-cholesterol;

V. FGF23 Calcium creatinine ratio in urine;

W. FGF23;

X. Calcium creatinine ratio in urine;

Y. Sodium creatinine ratio in urine;

Z. Abumin creatinine ratio in urine;

AA. Urine phosphate.
2. T = 0, 12 months:

A. 24-hr blood pressure (optional at T = 6 months).

1. Group 1: 2 oral tablets of cholecalciferol 1000 IE (= 50 microg) each day for 12 months;

2. Group 2: 2 placebo oral tablets each day for 12 months.

Placebo tablets are manufactured by the Central Hospital Pharmacy, The Hague.