Whirlpool EV130 E Instrukcja Użytkownika Pobierz pdf (Strona 182)

UV-Strahlungswirkungen

Vitamin D Status in Deutschland

Birte Hintzpeter

, Gert BM Mensink

, Christa Scheidt-Nave

Robert Koch-Institut, Seestraße 10, 13353 Berlin

1 Introduction

Vitamin D is unique as it can be produced from both endogenous sources through

ultraviolet-B (UVB) radiation of the skin as well as exogenous sources including in-

take of various dietary forms. There is general agreement that serum 25-OHD is the

best indicator of vitamin D status as it reflects the total production of vitamin D

from both endogenous and exogenous sources. However, it is difficult to clearly de-

fine cut-off levels for vitamin D deficiency. The question of an optimal threshold for

25-OHD concentrations has focused mainly upon the relationship between serum

PTH and serum 25-OHD. Hence, cut-off values can be set according to Lips. There

is no doubt that 25-OHD concentrations below 12.5 nmol/L can result in bone dis-

eases such as rickets among children or osteomalacia among adults. Values below 25

nmol/L can lead to functional alterations such as secondary hyperparathyroidism and

therefore to osteoporosis, especially in the elderly. In order to ensure normal bone

turnover, serum 25-OHD concentrations above 50 nmol/L are required, indicating a

vitamin D replete status.

There is increasing body of evidence from recent studies showing an inadequate vita-

min D status to be associated with the pathogenesis of various chronic diseases in-

volving the immune system and low grade inflammation. There is evidence that

1,25-OH

D is not exclusively produced in the kidney, but in many other tissues, such

as prostate, colon, skin and osteoblasts. This extrarenal synthesis occurs under the in-

fluence of cytokines and is important for paracrine regulation of cellular functions,

including cell growth. 1,25-OH

D has an antiproliferative effect and downregulates

inflammatory markers. Thus, vitamin D deficiency may play a role in the develop-

ment of several diseases such as multiple sclerosis, cardio vascular diseases, type 1

and 2 diabetes, and specific types of cancer .

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