Horm Metab Res 2009; 41(5): 402-407
DOI: 10.1055/s-0028-1128131
Humans, Clinical

© Georg Thieme Verlag KG Stuttgart · New York

Cyclic Changes of Vitamin D and PTH are Primarily Regulated by Solar Radiation: 5-Year Analysis of a German (50° N) Population

J. Reusch 1 , H. Ackermann 2 , K. Badenhoop 1
  • 1Department of Internal Medicine I, Division Endocrinology, J. W. Goethe University, Frankfurt, Germany
  • 2Department of Biomathematics, J. W. Goethe University, Frankfurt, Germany
Further Information

Publication History

received 23.05.2008

accepted 25.11.2008

Publication Date:
24 February 2009 (online)


Cutaneous vitamin D precursor production depends on UV-exposure and is ineffective in most regions above latitudes of 50° in winter. We hypothesized whether the cyclic course of vitamin D levels can be modelled with sunshine duration and would affect parathyroid hormone concentrations, but not calcium in a large patient population. We investigated 13330 blood samples from 6099 in- and out patients for 25(OH)D3, 1,25(OH)2D3, PTH, and total Ca in Frankfurt, Germany over 6.5 years. Vitamin D deficiency [25(OH)D3 <10 ng/ml] was found in 12.23% and vitamin D insufficiency [25(OH)D3 <20 ng/ml] in 40.62% of all the blood samples and more frequently during winter. We observed a significant difference between men and women, children and adults, migrants and local residents. Cycling of the curve was significantly related to Julian day for 25(OH)D3 and parathyroid hormone (PTH), but not for 1,25(OH)2D3 and Ca. The peak concentration of 25(OH)D3 was found at Aug 16th and correlated well with the length of day whereas PTH is inversely related with 25(OH)D3. Seasonal cycling of 25(OH)D3-levels correlated significantly with Julian Day and inversely with PTH. This tight feed back ensures stable Ca concentrations within narrow limits. We conclude that changes in vitamin D levels are mainly regulated by solar radiation and to a lesser degree by other factors such as nutrition.



J. Reusch

Department of Internal Medicine I

Division Endocrinology

J. W. Goethe University

Theodor-Stern-Kai 7

69590 Frankfurt/Main


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