Associations of Sun Exposure with 25-Hydroxyvitamin D and Parathyroid Hormone Levels in a Cohort of Hypertensive Patients : The Graz Endocrine Causes of Hypertension (GECOH)‎ Study

Abstract EN

Sunlight-induced vitamin D, synthesis in the skin is the major source of vitamin D, but data on the relationship of sun-related behaviour with vitamin D and parathyroid hormone (PTH) levels are relatively sparse.

We evaluated whether habitual sun exposure is associated with 25-hydroxyvitamin D (25[OH]D) and PTH levels and whether there exist seasonal variations.

We examined 111 hypertensive patients in Austria (latitude 47° N).

Frequent sunbathing at home and outdoor sports were associated with higher 25(OH)D levels (P<0.05 for both).

Red or blond scalp hair as a child, memory of sunburns, preferring sunbathing, frequent stays on the beach or in open-air pools, and solarium use were associated with lower PTH levels (P<0.05 for all).

Multiple linear regression analyses including age, sex, and body mass index showed that sun exposure score was significantly associated with 25(OH)D (beta coefficient=0.27; P=0.004) and by trend with PTH (beta coefficient=−0.16; P=0.09).

These associations were more prominent in summer in which 25(OH)D levels were significantly higher compared to winter.

Translation of these findings into recommendations for the prevention and treatment of vitamin D deficiency remains a challenge for the future.