Effect of cholecalciferol on the systolic blood pressure in hypertensive, vitamine D insufficient patients.

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 the relation of low vitamin D concentrations and hypertension shows that:
- the prevalence of hypertension increases when distance to the equator
increases
- in winter measured blood pressures are higher
- relative risk to hypertension increases strongly with
25-hydroxycholecalciferol concentrations below 37,5 nmol/l
- 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.
- the plasma renin activity (PRA) increases with decreasing vitamin D
concentrations
There is research done to confirm the anti-inflammatoire activity of vitamin D
in vitro by the CHDR in Leiden. In this research the anti-inflammatoire
activity of vitamin D in vivo will be investigated.

To evaluate the effect of cholecalciferol supplection on the systolic blood
pressure in hypertensive patients with a 25-hydroxycholecalciferol
insufficiency. Secondly, the effects on PRA, aldosteron,
25-hydroxycholecalciferol, alkaline phosphatase, PTH and the effect on the need
of adjusting the antihypertensive therapy are evaluated. Evaluation if the
anti-inflammatoire activity of vitamin D in vivo can be confirmed.

double blind, randomised, placebo-controlled intervention study.

group 1 takes 2 tablets of cholecalciferol 1000 IE each day for 12 months.
group 2 takes 2 placebo tablets each day for 12 months.
The placebo tablets are manufactured by the Central Hospital Pharmacy, The
Hague.

The extra load consists of 1 extra visit to the policlinic (including blood
pressure control, blood and urine sampling) and 2 times a 24-hrs bloodpressure
monitoring (+1x optional). In addition the subject needs to take 2 extra
tablets daily for 12 months.

The risk of adverse events with this dose of cholecalciferol and with the low
concentration of 25-hydroxycholecalciferol at the time of inclusion is very
low. The only known adverse event, which usually occurs only after taking high
daily doses chronically (> 10.000 IE per day) is hypercalcemia. By determining
the calciumconcentrations in blood every 6 months, we expect to recognize this
adverse event in an early stage. In addition all subjects are warned for the
adverse event and how to recognize it in an early stage (by: feeling of
weakness, fatigue, headage, dry mouth, nausea, vomiting, diarrhea, obstipation,
dizziness, disturbance of movement coordination, muscle- and bonepain, itch and
cardiac palpitation).

The extra load is considered to be mediocre, the risks to be minimal.