25-Hydroxyvitamin D response to cholecalciferol supplementation in hemodialysis.

Background And Objectives: Recent understanding of extrarenal production of calcitriol has led to the exploration of native vitamin D treatment in dialysis patients. This paper reports the pharmacokinetics of 25-hydroxyvitamin D response to 10,333 IU cholecalciferol given weekly in subjects on chronic dialysis.

Design, Setting, Participants, & Measurements: This randomized, double-blind, placebo-controlled trial of 15 weeks of oral cholecalciferol in subjects with stage 5 CKD requiring maintenance hemodialysis was conducted from November of 2007 to March of 2010.

Calcium supplementation does not augment bone gain in young women consuming diets moderately low in calcium.

In earlier observational work, the dietary calcium:protein ratio was directly related to bone accrual in healthy postadolescent women. In this study, we sought to test the hypothesis that augmented calcium intake would increase postadolescent skeletal consolidation, using a double-blind, randomized, placebo-controlled design. We recruited 152 healthy young women (age 23.

The elusive concept of bone quality.

This paper outlines information from recent publications that aid our understanding of bone quality in relation to osteoporosis. In practical terms, bone quality designates the properties of bone that contribute to strength but are not assessed by bone densitometry. While osteoporosis is still defined in terms of bone density, the limitations of this approach, long questioned, have become indisputable.

Calcium absorptive efficiency is positively related to body size.

Background: Calcium absorption efficiency is a more important determinant of calcium balance than calcium intake itself. The sources of variability in absorptive performance are only partly elucidated.

Purpose: The aim of the study was to explore the relationship between body size and calcium absorption efficiency.

Risedronate for prevention and treatment of osteoporosis in postmenopausal women.

Risedronate sodium is an N-containing bisphosphonate that has been approved for the prevention and treatment of osteoporosis in postmenopausal women. An increase in the rate of bone remodelling is a regular feature of oestrogen withdrawal during the menopausal transition, but excessive remodelling leads to bone fragility. Risedronate and similar compounds reduce the rate of bone remodelling by suppressing the action of osteoclasts.

Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol.

Background: The cholecalciferol inputs required to achieve or maintain any given serum 25-hydroxycholecalciferol concentration are not known, particularly within ranges comparable to the probable physiologic supply of the vitamin.

Objectives: The objectives were to establish the quantitative relation between steady state cholecalciferol input and the resulting serum 25-hydroxycholecalciferol concentration and to estimate the proportion of the daily requirement during winter that is met by cholecalciferol reserves in body tissue stores.

Design: Cholecalciferol was administered daily in controlled oral doses labeled at 0, 25, 125, and 250 micro g cholecalciferol for approximately 20 wk during the winter to 67 men living in Omaha (41.

Bone microstructure in osteoporosis: transilial biopsy and histomorphometry.

The bone fragility of osteoporosis is not fully explained by a deficit in bone mass. Histomorphometric examination of transilial bone biopsies has identified microstructural defects that-in light of what is known about the mechanical properties of structural materials-further compromise bone strength. Histomorphometric measures describe the biopsy specimen, the configuration of its trabeculae in space, and the extent to which its trabecular lattice is intact.

Effects of above average summer sun exposure on serum 25-hydroxyvitamin D and calcium absorption.

The purpose of this study was to examine the effects of summer sun exposure on serum 25-hydroxyvitamin D [25(OH)D], calcium absorption fraction, and urinary calcium excretion. Subjects were 30 healthy men who had just completed a summer season of extended outdoor activity (e.g.

Calcium and weight: clinical studies.

Data from six observational studies and three controlled trials in which calcium intake was the independent variable (and either bone mass or blood pressure the original outcome variable) have been reanalyzed to evaluate the effect of calcium intake on body weight and body fat. Analysis reveals a consistent effect of higher calcium intakes, expressed as lower body fat and/or body weight, and reduced weight gain at midlife. Similarly, studies relating nutrient intake to body composition report negative associations between calcium intake and body weight at midlife and between calcium and body fat accumulation during childhood.