Suppression of C-terminal telopeptide in hypovitaminosis D requires calcium as well as vitamin D.

We compared the effects of oral calcium and vitamin D separately and together on relevant variables in 22 postmenopausal volunteers with initial serum 25OHD levels below 60 nmol/L. Subjects were allocated randomly to two regimens: group 1 received 1 week of calcium 1,000 mg, followed by 7 weeks with additional vitamin D3 1,000 i.u.

Calcium malabsorption does not cause secondary hyperparathyroidism.

We challenge the widespread assumption that malabsorption of calcium per se causes secondary hyperparathyroidism. Serum parathyroid hormone (PTH) does not rise at the menopause despite the fall in calcium absorption, nor is it raised in osteoporotic women with vertebral fractures despite their low calcium absorption. The age-related rise in serum PTH can be accounted for by the age-related fall in serum 25(OH)D and/or decline in renal function with consequent loss of the calcemic action of vitamin D on bone.

Glucose tolerance and vitamin D: effects of treating vitamin D deficiency.

Objective: We investigated the effects of vitamin D treatment on plasma glucose, serum insulin, and insulin sensitivity in vitamin D-deficient individuals without diabetes mellitus.

Methods: Thirty-three adults with vitamin D insufficiency (serum 25-hydroxyvitamin D concentration < or = 50 nmol/L) and without diabetes (12 with impaired glucose tolerance) were given two oral doses of 100 000 IU of cholecalciferol, 2 wk apart. Before the first dose and 2 wk after the second dose, a 75-g oral glucose tolerance test was performed.

Vitamin D metabolites and calcium absorption in severe vitamin D deficiency.

Contrary to frequent claims, vitamin D insufficiency does not generally cause malabsorption of calcium because serum 1,25(OH)(2)D, which is the major determinant of calcium absorption, is maintained by secondary hyperparathyroidism. Nevertheless, because malabsorption of calcium has been described in osteomalacia, there must be a 25(OH)D level below which the serum 1,25(OH)(2)D can no longer be sustained, although it has never been defined. This paper seeks to define it.

Suppression of parathyroid hormone and bone resorption by calcium carbonate and calcium citrate in postmenopausal women.

This study was conducted to compare the suppressive effects of calcium carbonate and calcium citrate on bone resorption in early postmenopause. Calcium citrate is thought to be better absorbed. We therefore tested the hypothesis that calcium as citrate is more effective than calcium as carbonate in suppressing parathyroid hormone (PTH) and C-terminal telopeptide.

Misconceptions - vitamin D insufficiency causes malabsorption of calcium.

The negative effect of vitamin D insufficiency on bone is commonly attributed to a decrease in calcium absorption although little evidence has been produced to support this assumption. Using two previously published series of elderly patients we refute this common assumption and present evidence that low circulating levels of 25 hydroxyvitamin D have a direct and deleterious effect on bone.

Vitamin D, glucose, insulin, and insulin sensitivity.

This review examines available evidence of links between abnormalities of glucose and insulin metabolism and vitamin D deficiency. Possible mechanisms of action of vitamin D include stimulation of insulin secretion and effects on insulin sensitivity. Sun exposure usually implies greater outdoor physical activity, which in itself may have beneficial effects on insulin sensitivity, unrelated to serum 25-hydroxyvitamin D concentrations.

The importance of calculating absolute rather than relative fracture risk.

The relation between fracture risk and bone mineral density (BMD) is commonly expressed as a multiplicative factor which is said to represent the increase in risk for each standard deviation fall in BMD. This practice assumes that risk increases multiplicatively with each unit fall in bone density, which is not correct. Although odds increase multiplicatively, absolute risk, which lies between 0 and 1, cannot do so though it can be derived from odds by the term Odds/(1+Odds).

The effect of menopause on bone mineral density and bone-related biochemical variables in Indonesian women.

Objective: To determine the effects of menopause on bone-related variables in Indonesian women and to compare them with corresponding data in Caucasian Australian women.

Design: A study of bone-related variables in women aged 45-55 years in Jakarta compared with corresponding historical data from Caucasian Australian women.

Measurements: Dietary intakes, bone mineral density (BMD) and calcium-related variables in blood and urine.

Seasonal change in osteoid thickness and mineralization lag time in ambulant patients.

Unlabelled: Low vitamin D levels are common. Bone biopsies taken from 121 ambulant patients were therefore reviewed. Seasonal changes in mineralization correlated inversely with serum 25-hydroxyvitamin D but not the more active metabolite, 1,25-dihydroxyvitamin D.

A system for improving vitamin D nutrition in residential care.

Objective: To assess the feasibility of administering an inexpensive preparation of vitamin D(3) 100 000 IU orally 3 monthly to aged-care residents.

Design: Prospective, controlled open-label implementation trial.

Setting: Residential aged care, November 2003 to May 2004 (primary study).

Bone resorption markers in vitamin D insufficiency.

Severe vitamin D deficiency (serum 25 hydroxyvitamin D (25(OH)D) below 12.5 nmol/L) causes rickets and osteomalacia, but there is good evidence that lesser degrees of hypovitaminosis D (vitamin D insufficiency) have deleterious effects on bone and other organs. Evidence of impaired mineralization, suggestive of vitamin D insufficiency, has been found in bone biopsies of hip fracture patients in the UK, and several studies around the world have shown a rise in serum parathyroid hormone (PTH) as 25(OH)D levels fall below 50 nmol/L.

Relationship between fasting serum glucose, age, body mass index and serum 25 hydroxyvitamin D in postmenopausal women.

Objective: Because it has been reported that vitamin D, given to mother or infant, can prevent type I diabetes in children, that diabetes is more common in adults with low serum vitamin D and that insulin secretion and action are related to vitamin D levels in healthy young adults we examined the relationship between serum vitamin D metabolites and fasting serum glucose in patients attending our outpatient clinics.

Design: Retrospective examination of convenience sample of postmenopausal women attending our osteoporosis clinics.

Patients: A total of 753 postmenopausal women attending a university hospital outpatient clinic and not on any treatment known to affect glucose metabolism.

Does the response of bone mass to calcium supplements depend on calcium absorption efficiency?

Objective: Calcium supplements can reduce bone resorption and slow bone loss after the menopause, but these effects may be limited by poor intestinal absorption. Since the increase in blood ionised calcium and decrease in serum parathyroid hormone after a calcium load are diminished in patients with poor calcium absorption, we aimed to see whether the response of bone mineral content (BMC) to calcium is related to initial calcium absorption.

Design: We retrospectively examined the changes in forearm BMC in 164 patients (139 women and 25 men) receiving calcium therapy alone for low bone density in a university hospital.

Effect of age on calcium absorption in postmenopausal women.

Background: It is assumed that calcium absorption decreases with age, but this is not well documented. We report a study that addresses this issue.

Objective: The aim was to establish the extent and timing of any age-related change in calcium absorption in postmenopausal women.

A longitudinal study of bone-related biochemical changes at the menopause.

Objective: To evaluate the effects of the menopause on bone-related biochemical variables in a longitudinal study.

Design: Recruitment by advertisement of premenopausal women over the age of 44 for measurement of selected variables and collection of blood and urine samples for deep freezing, followed by annual check of menopausal status and repeat collection of blood and urine samples for deep freezing after the menopausal transition.

Patients: A total of 104 women with confirmed premenopausal status and on no treatment likely to affect calcium or bone metabolism were admitted to the study over a period of 2 years.

The effects of age and other variables on serum parathyroid hormone in postmenopausal women attending an osteoporosis center.

It has been known for many years that serum PTH rises with age, and it has been suggested that this rise may contribute to bone loss in postmenopausal women. It has been variously attributed to declining renal function, declining calcium absorption efficiency, and declining serum 25-hydroxyvitamin D [25(OH)D] levels. We studied the effects of age, weight, renal function, radiocalcium absorption, serum ionized calcium, and serum 25(OH)D on serum PTH levels in 918 postmenopausal women attending an osteoporosis center.

Radiocalcium absorption is reduced in postmenopausal women with vertebral and most types of peripheral fractures.

Intestinal calcium absorption accounts for 60% of the variance in calcium balance and is therefore a potentially very important determinant of bone status. Whether measured by the balance technique or with radiocalcium, it is known to be significantly reduced in postmenopausal women with vertebral and hip fractures. By contrast, there is very little information about calcium absorption in other types of postmenopausal fracture.

Efficacy and safety of raloxifene 60 milligrams/day in postmenopausal Asian women.

In healthy Caucasian postmenopausal women, raloxifene increases bone mineral density (BMD), decreases biochemical markers of bone turnover, and lowers low-density lipoprotein (LDL) cholesterol, without effects on high-density lipoprotein (HDL) cholesterol and triglycerides. This randomized, double-blind study examines the effects of raloxifene 60 mg/d (n = 483) or placebo (n = 485) in healthy postmenopausal Asian women (mean age 57 yr) from Australia, Hong Kong, India, Indonesia, Malaysia, Pakistan, Philippines, Singapore, Taiwan, and Thailand. Serum osteocalcin, serum N-telopeptide, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides were assessed at baseline and 6 months.

Additive effects of raloxifene and alendronate on bone density and biochemical markers of bone remodeling in postmenopausal women with osteoporosis.

Both raloxifene (RLX) and alendronate (ALN) can treat and prevent new vertebral fractures, increase bone mineral density (BMD), and decrease biochemical markers of bone turnover in postmenopausal women with osteoporosis. This phase 3, randomized, double-blind 1-yr study assessed the effects of combined RLX and ALN in 331 postmenopausal women with osteoporosis (femoral neck BMD T-score, less than -2). Women (aged < or = 75 yr; > or = 2 yr since their last menstrual period) received placebo, RLX 60 mg/d, ALN 10 mg/d, or RLX 60 mg/d and ALN 10 mg/d combined.