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Biomedical subjects

A G Need

Publications and source records attributed to A G Need.

At least 55 records · Page 3Linked to original sources
PubMed1993

A 5-year longitudinal study of forearm bone mass in 307 postmenopausal women.

We measured forearm bone mineral content at the beginning and end of a 5 year period in 307 untreated postmenopausal volunteers. We also measured height, weight, and a number of biochemical variables in plasma and urine after an overnight fast. The initial mean age of the subjects was 59.0 years (range 39-72), and the mean years since menopause was 10.0 (range 1-37). The mean forearm BMC fell from 1034 +/- 9.6 (SEM) to 982 +/- 9.3 mg/cm (P < 0.001). The coefficient of correlation between the first and second measurements was 0.96. The mean rate of change was -1.0% per annum (with a 99% range of -4 to 1% per annum), which agreed well with previous estimates from cross-sectional data. There was a significant negative correlation between rate of change in bone mass and initial value (r = -0.23; P < 0.001), which was eliminated by expressing change as a percentage of initial bone mass. Of the other variables measured, the one that was most significantly related to the percentage change in bone mass was the urinary hydroxyproline/creatinine ratio (r = -0.35; P < 0.001), which we regard as a marker only. By stepwise regression, the only significant determinants of the rate of change in bone mass were body weight (positive, P < 0.001), years since menopause (positive, P < 0.005), urine calcium (negative, P < 0.01), and serum estrone (positive, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effects of skin thickness, age, body fat, and sunlight on serum 25-hydroxyvitamin D.

We tested the hypothesis that the age-related decline in skin thickness may contribute to the age-related decline in serum 25-hydroxyvitamin D [25(OH)D]. We measured skinfold thickness on the back of the hand, serum 25(OH)D, height, and weight in 433 normal postmenopausal women. We also noted the average daily hours of sunlight in the month in which the observations were made and in the preceding 2 mo. Serum 25(OH)D was positively related to hours of sunlight (with a time lag of 2 mo) and to skin thickness, and negatively to body mass index (wt/ht2). Serum 25(OH)D fell significantly after age 69 y. Seasonal variation of serum 25(OH)D was greater in lean than in fat subjects, which we attributed to the larger fat mass and consequent larger pool size in the latter group. The results suggest that the tendency for serum 25(OH)D to fall with age is due in part to the age-related decline in skin thickness.

Adipose Tissue↗
PubMed1993

The nature and significance of the relationship between urinary sodium and urinary calcium in women.

Orally or parenterally administered sodium is known to increase urinary calcium in experimental animals and humans, and there is well-documented correlation between urinary sodium and calcium in 24-h urine collections from normal subjects and renal stone formers. The correlation between urinary sodium and calcium is generally sodium driven, i.e., it is the sodium load that influences urinary calcium rather than vice versa, but the converse may also occur, as after an oral calcium load or in hypercalcemia. When sodium is the determinant, 100 mmol of sodium takes out approximately 1 mmol of calcium in the urine. When calcium load is the determinant, each millimole of calcium appearing in the urine is associated with an extra 10-20 mmol of sodium. Sodium-dependent calcium loss may continue indefinitely, but calcium-dependent natriuresis is self-limiting. There is a significant correlation between calcium and sodium in fasting urine from both pre- and postmenopausal women, but there is more calcium relative to sodium in postmenopausal women than in premenopausal women. In postmenopausal but not premenopausal women, urinary hydroxyproline is also related to obligatory sodium and calcium output, and restriction of salt intake lowers not only urinary sodium but also calcium and hydroxyproline. There is not only an increase in obligatory calcium excretion at the menopause, but also an increase in the fasting urinary sodium, which in turn accounts for some of the increase in calcium output. This rise in fasting urinary sodium represents a delay in sodium excretion that may have a significant effect on calcium homeostasis.

Adult↗
PubMed1993

Effects of norethisterone on bone related biochemical variables and forearm bone mineral in post-menopausal osteoporosis.

OBJECTIVE: Progestogens may be a useful therapeutic alternative to oestrogen in the treatment of post-menopausal osteoporosis. The purpose of this study was to determine the effects of norethisterone on forearm bone mineral content and bone related biochemical variables in patients with post-menopausal osteoporosis. DESIGN/PATIENTS: The effects of treatment with norethisterone (5 mg/day) on bone related biochemical variables was determined in 44 women with post-menopausal osteoporosis. The effects of norethisterone on forearm bone mineral content (FMC) were evaluated by serial measurements in 39 of these women. MEASUREMENTS: We measured forearm mineral content, forearm mineral density, forearm fat content and fat-corrected forearm mineral density. Biochemical measurements included plasma calcium and plasma calcium fractions (ionized, protein bound, complexed and ultrafiltrable), alkaline phosphatase, bicarbonate, phosphate, albumin and globulins, serum parathyroid hormone, osteocalcin and 1,25-dihydroxyvitamin D, radiocalcium (45Ca) absorption and fasting urinary calcium/creatinine, sodium/creatinine, phosphate/creatinine and hydroxyproline/creatinine molar ratios. RESULTS: After 4 months of treatment norethisterone produced a fall in plasma calcium (mean +/- SEM from 2.40 +/- 0.14 to 2.32 +/- 0.13 mmol/l, P < 0.001), primarily in the non-ionized calcium, due to a decrease in plasma bicarbonate (from 29 +/- 0.28 to 27 +/- 0.28 mmol/l, P < 0.001). There were decreases in urinary calcium/creatinine (from 0.41 +/- 0.03 to 0.19 +/- 0.02, P < 0.01) and sodium/creatinine (from 15 +/- 1.1 to 10 +/- 0.93, P < 0.001) molar ratios and a rise in the renal tubular maximum for calcium reabsorption (TmCa) (from 2.36 +/- 0.041 to 2.55 +/- 0.059 mmol/l of glomerular filtrate, P < 0.001). Plasma phosphate, urinary phosphate/creatinine and tubular maximum for phosphate reabsorption (TMP) all fell (P < 0.01). Both the urinary hydroxyproline/creatinine (P < 0.001) and plasma alkaline phosphatase (P < 0.001) fell. Serum parathyroid hormone rose from 4.1 +/- 0.36 to 5.5 +/- 0.51 pmol/l (P < 0.02) and radiocalcium absorption increased from 0.67 +/- 0.08 to 0.81 +/- 0.10 fx/h (P < 0.01). There was no change in serum 1,25-dihydroxy vitamin D. After treatment with norethisterone for 4 months there was an increase in forearm bone mineral content (P < 0.05) and a decrease in forearm fat content (P < 0.02). After two years treatment with norethisterone fat-corrected forearm bone mineral content rose (mean change 17.0 +/- 5.5 mg/cm, P < 0.01). CONCLUSIONS: These results suggest that norethisterone prevents bone loss in post-menopausal osteoporosis by decreasing bone turnover, has a vitamin-D independent effect on intestinal calcium absorption, and increases serum parathyroid hormone levels.

Adult↗
PubMed1993

The effect of chlorothiazide on bone-related biochemical variables in normal post-menopausal women.

OBJECTIVE: To evaluate the effects of short-term administration of chlorothiazide on fasting urinary hydroxyproline, an index of bone resorption, and other bone-related biochemical parameters in normal post-menopausal women. DESIGN: Subjects served as their own control before and after chlorothiazide treatment. SETTING: Subjects were recruited by advertisement. PARTICIPANTS: Thirteen healthy post-menopausal women with a mean age of 65 years. INTERVENTION: Each subject was given chlorothiazide 500 mg bd po for 7 days. Fasting blood and urine samples were obtained immediately before the commencement of chlorothiazide (day 1) and 2 and 7 days after starting chlorothiazide. RESULTS: Chlorothiazide decreased the urinary calcium/creatinine (mean value day 1, 0.267; day 2, 0.143; day 7, 0.135; P < 0.001) and hydroxyproline/creatinine (day 1, 0.0192; day 2, 0.0145; day 7, 0.0139; P < 0.02) molar ratios. CONCLUSION: Chlorothiazide decreases fasting urinary hydroxyproline, a marker of bone resorption in post-menopausal women. This observation supports a potential role for thiazide diuretics in the prevention of osteoporosis. The observed fall in urinary hydroxyproline is of the same order as that seen after treatment with estrogen or calcium supplements.

Acid-Base Equilibrium↗
PubMed1993

Relationships between metacarpal morphometry, forearm and vertebral bone density and fractures in post-menopausal women.

The relationships between metacarpal morphometric, vertebral and forearm density measurements and the prevalence of vertebral and peripheral fractures were examined in 239 postmenopausal women (median age 63, range 32-84 years). Metacarpal cortical area/total area ratio (CA/TA) was measured with needle calipers, forearm mineral density (FMD) by single photon absorptiometry and vertebral mineral density (VMD) by single energy quantitative computed tomography. Of the 239 subjects 97 had not suffered any fractures, 44 had at least one previous vertebral fracture but no peripheral fractures, 41 had a history of peripheral fracture but no vertebral fracture and 57 had suffered both peripheral and vertebral fractures. There were significant correlations between a single measurement of CA/TA and both FMD (r = 0.65, p < 0.001) and VMD (r = 0.41, p < 0.001). Similar correlations existed between the mean of multiple measurements of CA/TA and both FMD and VMD. CA/TA (p < 0.001), FMD (p < 0.001) and VMD (p < 0.001) were reduced in subjects who had suffered fractures, when compared with the no fracture group. The percentage of cases in each of the four fracture groups (vertebral fracture only, peripheral fracture only, peripheral and vertebral fracture, peripheral or vertebral fracture) misclassified with reference to the no fracture group were similar with CA/TA, FMD or VMD measurements. We suggest that metacarpal morphometry, which is widely available at relatively low cost, yields cross-sectional information about bone density and fracture risk, comparable with that obtained by forearm and vertebral densitometry.

Absorptiometry, Photon↗
PubMed1993

Anabolic steroids in postmenopausal osteoporosis.

The anabolic steroids were first developed in the 1950's to provide the anabolic advantages of androgens with less androgenic action. They are widely used in the treatment of osteoporosis, although their effectiveness has only recently been demonstrated with the advent of bone densitometry. It is now established that their administration leads to a significant increase in bone mass in osteoporotic men and women associated with an apparent conversion of fat into muscle tissue. The bone gain is of the order of 3% per annum but the maximal effect is obtained in the first few months. The bone gain is probably due to stimulation of bone formation and is associated with elevation of serum albumin and fat-free skinfold thickness. The most serious side-effect with parenteral use is lowering of voice pitch but there is some evidence that oral anabolic steroids may adversely affect liver function. The optimum dose and duration of therapy has not yet been established.

Adult↗
PubMed1992

Effects of oophorectomy on biochemical and bone variables in the rat.

The metabolic effects of oophorectomy (Oophx) were studied in 6-month-old rats maintained on a normal chow diet. Nine weeks following operation, Oophx animals had a significantly lower femoral trabecular bone volume (BV/TV) than sham-operated animals; mean (SD) Oophx 8.5 (3.8)%; Sham 13.4 (2.5)%; P = 0.013). They also had a higher urine hydroxyproline (P less than 0.001), serum alkaline phosphatase activity (P less than 0.001), serum phosphate (P less than 0.001) and lower serum albumin (P less than 0.001) than the controls. Serum osteocalcin was inversely related to the BV/TV in the Oophx animals at 9 weeks post operation (r = -0.85, P = 0.007, n = 8). A fall in serum ionized calcium from 3 to 9 weeks post operation correlated with a fall in urinary hydroxyproline in the Oophx animals (r = 0.57, P = 0.002, n = 27). The data are consistent with a model of ovarian hormones acting directly to modulate bone cell activity as well as exerting an effect on the renal handling of phosphate.

Alkaline Phosphatase↗
PubMed1992

Osteoporosis and Klinefelter's syndrome.

OBJECTIVE: We wanted to measure forearm mineral density and bone-related biochemical variables in patients with Klinefelter's syndrome. DESIGN: Measurements made in patients with Klinefelter's syndrome were compared to those obtained in age-matched normal male volunteers. PATIENTS: We studied 22 patients with Klinefelter's syndrome (12 of whom had received sex hormone therapy) and 22 control subjects. MEASUREMENTS: We measured forearm mineral density, forearm fat content, fat-corrected forearm mineral density, plasma calcium and ionized calcium, serum osteocalcin, testosterone and dehydroepiandrosterone sulphate, and urinary hydroxyproline/creatinine ratio. RESULTS: Forearm mineral density was lower in the Klinefelter's group than in the control subjects (P less than 0.05) and below the control range in 5 patients. The fat content of the forearm was greater in the Klinefelter's group (P less than 0.002). Serum osteocalcin and testosterone were lower, while ionized calcium and the urinary hydroxyproline/creatinine ratio were higher in the Klinefelter's group (P less than 0.002). Serum dehydroepiandrosterone sulphate and testosterone were significantly related in the Klinefelter's group (r = 0.64, P less than 0.001), but not in the controls (r = 0.22, NS). Forearm mineral density and fat-corrected forearm mineral density were significantly related to serum testosterone in the Klinefelter's group (r less than 0.63; P less than 0.01), but not in the control subjects (r less than 0.03, NS). CONCLUSIONS: Decreased bone density occurs in about 25% of patients with Klinefelter's syndrome and probably reflects both decreased bone formation and increased bone resorption.

Adult↗
PubMed1992

Trabecular spacing in post-menopausal Australian women with and without vertebral fractures.

Histomorphometric measurements were made from iliac crest biopsies of 32 women with vertebral fractures and 37 women without fracture. All were post-menopausal Australian women who had presented with back pain to a hospital out-patient endocrinology clinic. Bone from the fracture cases was characterised by loss of individual trabecular elements, with the remaining trabeculae being spaced further apart than those in the non-fracture women (p less than 0.0001). This resulted in a significant decrease in trabecular bone volume (p less than 0.01). In addition osteoid surface was reduced (p less than 0.01). Dynamic parameters of bone turnover were not significantly different between the two groups. These data should be useful for the assessment of iliac bone histomorphometry in Australian post-menopausal women suspected of having osteoporosis.

Aged↗
PubMed1992

Relative contributions of years since menopause, age, and weight to vertebral density in postmenopausal women.

Vertebral mineral density (VMD) was measured by quantitative computerized tomography (QCT) in 16 premenopausal and 243 untreated postmenopausal women without vertebral compression. The mean VMD in the premenopausal group was 157 +/- 10.1 mg/mL, which is close to previously reported values. In the postmenopausal women, VMD fell significantly with age and years since menopause (YSM) separately and together, but the relation to YSM was more significant than that to age. After logarithmic transformation of YSM, the fall in bone density with logYSM was highly significant (P less than 0.001), and that with age was not quite significant. In 36 pairs of women matched for YSM, there was no significant difference in VMD between the subjects up to and over 55 yr of age. In 32 pairs matched for age, VMD was significantly lower in those over 55 yr than in those up to 55 yr (P = 0.005). There was also a significant correlation between VMD and body weight. After this was allowed for, the correlation between VMD and logYSM remained highly significant, but the correlation with age was not significant. We conclude that the fall in vertebral body trabecular bone in postmenopausal women is self-limiting, amounts to about 35% bone loss in 25 yr (most of it in the first 5 yr), and corresponds to but is proportionately greater than the trabecular component in postmenopausal forearm bone loss.

Adult↗
PubMed1991

Calcium absorption in normal and osteoporotic postmenopausal women.

Hourly fractional absorption of radiocalcium (alpha), serum calcitriol, and a number of other variables were measured in 152 normal and 148 osteoporotic postmenopausal women. Alpha, body weight, and serum albumin were all significantly lower in the osteoporotic than in the normal women, and plasma alkaline phosphatase, fasting urinary calcium, sodium, and hydroxyproline were all significantly higher in the osteoporotic than in the normal group. The most significant determinant of alpha in each group was the serum calcitriol concentration, but calcium absorption relative to serum calcitriol was significantly lower in the osteoporotic than in the normal women. The serum calcitriol level was slightly but not significantly lower in the osteoporotic than in the normal group and accounted for only 20% of the difference in alpha between them. The implied "resistance" to calcitriol in the osteoporotic group was significantly related to serum albumin and body weight but independent of age. Urinary hydroxyproline was an inverse function of alpha and a positive function of fasting urinary calcium in the osteoporotic group.

Absorption↗
PubMed1991

Cross sectional and longitudinal study of bone mineral content of the distal forearm in adult premenopausal women.

The range of fat corrected distal forearm mineral content (FMC) (at a site which comprises approximately 75% cortical and 25% trabecular bone) and the effect of aging on FMC were determined in normal premenopausal women. In 106 women (mean age 39; range 18-56) the mean FMC was 1.184 (SD 148) g/cm; fat correction increased this to 1.239 (SD 148) g/cm. There were significant correlations between fat corrected FMC and height, weight and BMI (r greater than 0.16; P less than 0.05). In 43 of these women (mean age 35; range 18-51) repeat measurements of FMC were performed. The last measurement was separated from the first by a mean time interval of 27 +/- 3 months. There was no significant change in uncorrected FMC (baseline 1.185 +/- 0.21 g/cm compared with their final measurement 1.182 +/- .020 g/cm; P = 0.51). Fat-corrected FMC (baseline 1.229 +/- .021 g/cm compared with 1.223 +/- .020 g/cm later) tended to decrease although this change was not significant (P = 0.06). Age ranked cusum analysis demonstrated a non-significant fat-corrected rate of change in FMC of -.3% yr in those over 35 years of age (P less than 0.10). This data suggests that if there is any distal forearm bone loss before the menopause it is negligible.

Adolescent↗
PubMed1991

Evidence for a renal calcium leak in postmenopausal women.

We have measured calcium, albumin, globulin, bicarbonate, and anion gap in the plasma; and calcium, sodium, and creatinine in the urine, in 115 premenopausal and 140 postmenopausal normal women after an overnight fast, and calculated the calcium fractions in the plasma and the calcium/and sodium/creatinine ratios in the urine. The total ultrafiltrable calcium was significantly higher in the postmenopausal group, mainly due to their higher complexed calcium fraction, due in turn to their higher bicarbonate and anion gap concentrations. Urinary calcium was also significantly higher in the postmenopausal group even after correcting for sodium. After matching for total calcium and each of the calcium fractions in turn, the urinary calcium remained significantly higher in the post- than in the premenopausal sets even after correction for sodium. The implication is that the rise in urinary calcium at the menopause is due to reduced tubular reabsorption of calcium rather than to an increase in filtered load. We suggest that estrogens promote tubular reabsorption of calcium and that the rise in bone resorption at the menopause could be accounted for, at least in part, by the effect of estrogen deficiency on the kidney.

Acid-Base Equilibrium↗
PubMed1991

Effects of three different calcium preparations on urinary calcium and hydroxyproline excretion in postmenopausal osteoporotic women.

Some authors have claimed that 'solubilized' calcium preparations are better absorbed than calcium carbonate, while others have reported that all forms are equally well absorbed. We measured radiocalcium absorption in 35 postmenopausal osteoporotic women and then gave them on three successive evenings, in random order, three different proprietary calcium preparations (Sandocal containing 1 g of effervescent calcium, Calsup containing 1 g of calcium as the carbonate, and Caltrate containing 1.2 g of calcium as the carbonate). The daily urinary calcium excretion rose significantly and similarly on all three supplements and was greater in the high calcium absorbers than the low calcium absorbers. The fasting urinary hydroxyproline excretion was significantly decreased the morning after administration of each preparation, and one-way analysis of variance showed no significant difference between the days of administration or the type of supplement. The decrease was greater for high absorbers than for low absorbers on all three supplements but the differences did not reach statistical significance. By 36 hours after the last calcium supplement the urinary hydroxyproline had returned to baseline. The response of hydroxyproline excretion (and by implication bone resorption) appears to be rapid in onset and short lived. Strict compliance is therefore important in patients on calcium therapy.

Absorption↗