Search Results

You are looking at 1 - 3 of 3 items for

  • Author: Jan Stepan x
Clear All Modify Search
Free access

David Cibula, Jana Skrenkova, Martin Hill and Jan J Stepan

Background

The aim was to evaluate changes of bone mineral density (BMD) and markers of bone turnover in healthy adolescents, and in adolescent users of combined oral contraceptives (COCs) with different ethinylestradiol (EE) contents.

Methods

In this prospective crossover study, 56 healthy females (15–19.5 years) with desire to use hormonal contraception were randomized to COC with either 30 or 15 μg of EE in crossover design of 9-month intervention each in reverse order. Nonusers of the same age (n=28) served as controls. BMD at lumbar spine (LS), total femur, femoral neck, distal radius, and total body, and serum markers (N-propeptide of type I procollagen, and type I collagen C-telopeptide) were measured at baseline and after 9 and 18 months.

Results

In COC nonusers, BMD significantly increased at LS and radius, while markers decreased. In COC users, BMD did not increase, with the exception of LS BMD in the 30 μg COC group (P<0.05). In the crossover design, a difference between the low- and very low-dose COC users was found in LS BMD changes (P<0.05), where increase in BMD was more impaired in the 15 μg COC users. The skeletal effects of COC remained significant after adjustments for age and smoking status. Markers declined faster in COC users during the first period, while they remained stable or even increased during the second 9 months.

Conclusion

Physiological acquisition of LS BMD during adolescent age may be prevented by use of COC, especially those containing very low dose of EE.

Free access

Maria Luchavova, Vit Zikan, Dana Michalska, Ivan Raska Jr, Ales A Kubena and Jan J Stepan

Background

We hypothesized that with the administration of teriparatide (TPTD) treatment at different times, we would be able to modify the physiological circadian rhythm of bone turnover.

Methods

The concentration of serum C-terminal telopeptide of collagen type I (βCTX), serum N-terminal propeptide of procollagen type I (P1NP), serum ionized calcium (iCa), and plasma PTH were measured every 3 h over a 24 h period in 14 postmenopausal osteoporotic women (aged 72.4±9.3 years) treated with 20 μg TPTD for long term, given at different times of the day. General linear model-repeated measurements (GLM RM) were performed to analyze the circadian rhythms as well as intergroup comparisons.

Results

GLM-RM for both related groups showed a significant influence of time of day on all measured variables except P1NP. The analysis for each group separately provided a powerful model for βCTX (P<0.001, η 2=0.496), serum iCa (P<0.001, η 2=0.423), plasma PTH (P<0.001, η 2=0.283), and serum PINP (P<0.001, η 2=0.248). While the evening TPTD treatment showed a marked circadian rhythm for serum βCTX, the morning TPTD treatment rather suggested circasemidian rhythm. The P1NP rhythm followed a much smaller amplitude of the rhythm than βCTX. Changes in serum iCa were positively related to changes in serum βCTX (P<0.001) and negatively related to changes in PTH (P<0.001).

Conclusion

Timing of TPTD administration may significantly change the 24 h variation in bone turnover markers as well as calcium-parathyroid axis in postmenopausal osteoporotic women.

Free access

Paul Lips, Kevin D Cashman, Christel Lamberg-Allardt, Heike Annette Bischoff-Ferrari, Barbara Obermayer-Pietsch, Maria Luisa Bianchi, Jan Stepan, Ghada El-Hajj Fuleihan and Roger Bouillon

Vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) <50 nmol/L or 20 ng/mL) is common in Europe and the Middle East. It occurs in <20% of the population in Northern Europe, in 30–60% in Western, Southern and Eastern Europe and up to 80% in Middle East countries. Severe deficiency (serum 25(OH)D <30 nmol/L or 12 ng/mL) is found in >10% of Europeans. The European Calcified Tissue Society (ECTS) advises that the measurement of serum 25(OH)D be standardized, for example, by the Vitamin D Standardization Program. Risk groups include young children, adolescents, pregnant women, older people (especially the institutionalized) and non-Western immigrants. Consequences of vitamin D deficiency include mineralization defects and lower bone mineral density causing fractures. Extra-skeletal consequences may be muscle weakness, falls and acute respiratory infection, and are the subject of large ongoing clinical trials. The ECTS advises to improve vitamin D status by food fortification and the use of vitamin D supplements in risk groups. Fortification of foods by adding vitamin D to dairy products, bread and cereals can improve the vitamin D status of the whole population, but quality assurance monitoring is needed to prevent intoxication. Specific risk groups such as infants and children up to 3 years, pregnant women, older persons and non-Western immigrants should routinely receive vitamin D supplements. Future research should include genetic studies to better define individual vulnerability for vitamin D deficiency, and Mendelian randomization studies to address the effect of vitamin D deficiency on long-term non-skeletal outcomes such as cancer.