To study seasonal inter-individual and intra-individual variations in serum 25-hydroxy vitamin D (25(OH)D) and to explore parameters associated with 25(OH)D in a healthy Swedish adult population. 540 blood donors (60 % men; mean age 41 ± 13 years) and 75 thrombocyte donors (92 % men, aged 46 ± 11 years) were included. Serum was collected during 12 months and analyzed for 25(OH)D and parathyroid hormone (S-iPTH). The blood donors answered questionnaires concerning vitamin D supplements, smoking, physical activity, sunbed use and sun holidays. Repeated serum samples were collected from the thrombocyte donors to study the intra-individual variations in S-25(OH)D. S-25(OH)D varied greatly over the year correlating with the intensity of the UV-B irradiation (rS = 0.326; p < 0.001). During January–March, a S-25(OH)D level below the thresholds of 50 and 75 nmol/L was observed in 58 and 88 %, respectively, and during July–September in 11 and 50 % (p < 0.001). S-25(OH)D was negatively correlated with body mass index and S-iPTH, but was significantly higher in holiday makers in sunny destinations, sunbed users, non-smokers, and in the physically active. The intra-individual analyses showed a mean increase in S-25(OH)D by 8 nmol/L/month between April and August. Approximately 75 % had serum 25(OH)D values <75 nmol/L during 75 % of the year and 50 % had serum 25(OH)D <50 nmol/L during 50 % of the year. Serum 25(OH)D was strongly associated with parameters related to sun exposure, but only weakly with intake of vitamin D supplements.

Objective: To study secular trends in sex hormones, anthropometry, bone measures and fractures. Design: A random population sample was studied twice and subjects of similar age group were compared 13 years apart. Methods: X-ray-verified fractures were retrieved from a random population sample of 2400 men and women (participants 1616Z67%) aged 25-64 years from the WHO, MONICA Project in Gothenburg, Sweden, in 1995 and. Fasting serum hormones and calcaneal ultrasound were measured in every fourth subject. In fertile women, measurements were performed on cycle day interval 7-9. Results: In 2008, men had lower serum free testosterone than men of similar age in 1995 (P!0.001). Body composition, physical activity and fracture incidence were similar. In women, hormone replacement therapy (HRT) was lower in 2008, 7 vs 28% (P!0.0001), as was serum oestradiol, although use of tranquilisers and leisure time physical activity were higher. In 2008, the fracture incidence was higher in postmenopausal women, 29 vs 17% (P!0.001), and vertebral crush had increased from 8 to 19% of all fractures (PZ0.031). Serum cholesterol and triglycerides were lower in all subjects in 2008 compared with that in 1995. Conclusions: Secular trends were observed with lower serum testosterone in men in 2008, but no effect was seen on the fracture incidence of these fairly young men. In postmenopausal women in 2008, there was a higher fracture incidence along with more vertebral compressions. Lower HRT use, lower serum oestradiol and higher fall risk exposure due with more tranquilisers and leisure time physical activity in 2008 may explain the results.

SummaryObjectiveThere is limited knowledge about the natural history of normocalcaemic, vitamin D‐sufficient hyperparathyroidism (nHPT). The aim was to study the prevalence of nHPT and its relation to morbidity.DesignCross‐sectional and retrospective study at the Sahlgrenska University Hospital, Gothenburg, Sweden.SubjectsA random population of 608 men and women, age 25–64 years, was studied in 1995 as part of the WHO MONICA study and reinvestigated in 2008 (n = 410, of whom 277 were vitamin D sufficient).MeasurementsA serum intact parathyroid hormone (S‐PTH) ≥60 ng/l was considered as HPT, S‐calcium 2·15–2·49 mmol/l as normocalcaemia and S‐25(OH)D ≥ 50 nmol/l as vitamin D sufficiency. Data on fractures, stroke and myocardial infarction were retrieved until 2013, that is a 17‐year follow‐up.ResultsThe prevalence of nHPT was 2·0% in 1995 (age 25–64) and 11·0% in 2008 (age 38–79). S‐PTH was positively correlated with age and BMI. After adjustment for these variables, a high S‐PTH level (≥60 ng/l) at follow‐up was associated with previously low S‐25(OH)D, high osteocalcin, S‐PTH and both past and presently treated hypertension. No relation was seen with creatinine, cystatin C, malabsorption markers, thyroid function, glucose, insulin, lipids, calcaneal quantitative ultrasound, fractures, myocardial infarction, stroke or death at follow‐up.ConclusionsThis small random population study showed that nHPT was common, 11% at follow‐up. Only one individual developed mild hypercalcaemia in 13 years. Previous S‐PTH was predictive of nHPT and hypertension was prevalent, but no increase in hard end‐points was seen over a 17‐year period.