Serum alkaline phosphatase during hormone treatment in early postmenopausal women. A model for establishing optimal prophylaxis and treatment in postmenopausal osteoporosis

Sub-chronic exposure to low concentration of dibutyl phthalate affects anthropometric parameters and markers of obesity in rats

Dibutyl phthalate is an important phthalate ester extensively used in various products like plastics, adhesives, inks, pharmaceuticals, lacquers, varnishes, paper coatings, safety glasses, and cosmetics. The exposure of DBP to "one's health" is therefore inevitable. The present study focuses on elucidating the effect of low doses of DBP on anthropometric parameters and markers of obesity in rats in a 13-week study. A total of 48 rats were divided into three treatment groups as mg DBP/kg body weight per day: (a) 0 mg/kg (control), (b) 10 mg/kg (DBP-10), and (c) 50 mg/kg (DBP-50). The rats in each treatment (n = 16) were further equally divided into male and female rats for studying treatment and gender interaction. Anthropometric parameters, nutritional determinants, and markers of obesity in rats were studied. Two-way ANOVA was used to analyze the data (p < 0.05). Tukey's post hoc test was used for pairwise comparisons. DBP increased body weight gain, feed efficiency, abdominal to thoracic circumference ratio, and body mass index in rats. Serum cholesterol and alkaline phosphatase concentrations decreased with DBP treatment. Serum albumin, glucose, creatinine, and alanine transaminase increased with DBP treatments. Serum lactate dehydrogenase increased in DBP-10 but was not affected by DBP-50. Further low-dose investigations are needed to assess non-monotonic dose responses.

Assessment of osteoporotic alterations in achondroplastic patients: a case series

Achondroplasia (ACH) is the most common form of human dwarfism and has been associated with biochemical alterations of the bone tissue, also observed in cases of osteoporosis. The present case series aimed at assessing low bone density, diagnosed with spinal bone mineral density (BMD) analysis and with panoramic radiograph measurements, in ACH patients. Spinal BMD was measured by means of dual-energy X-ray absorptiometry at the lumbar region (L1-L4). On dental panoramic radiographs of the patients, the mandibular cortical width was measured separately on the right and left sides. The Klemetti Index was also assigned as appropriate for evaluating the cortical area below the mandibular foramen. Additional parameters such as patient age, gender, body mass index, and number of teeth were also recorded. BMD results showed that 5/11 cases presented with skeletal osteopenia/osteoporosis diagnoses. Additionally, mandibular cortical erosion was detected in panoramic radiographs in 8/11 cases. The BMD and panoramic radiographic alterations found in this study suggest that the diagnosis of low bone density may have a special clinical relevance in cases of bone tissue disorders, such as achondroplasia.

Effect of estrogen and calcitonin therapies on bone density in a lateral area adjacent to implants placed in the tibiae of ovariectomized rats

BACKGROUND

This study evaluated the influence of estrogen and calcitonin administration on tibial bone density in a lateral area adjacent to implants placed in ovariectomized rats (OVX).

METHODS

One screw-type titanium implant was placed bilaterally in the ovariectomized rats, and the animals assigned to one of the following groups: group 1 (n = 15): sham surgeries; group 2 (n = 15): OVX; group 3 (n = 14): OVX subcutaneously administered with calcitonin (CT) 4 days/week (16 IU/kg); group 4 (n = 14): OVX administered daily with 17beta estradiol (20 microg/kg). After 60 days, the animals were sacrificed and undecalcified sections obtained. Blood samples were collected to measure serum levels of alkaline phosphatase and calcium at the time of sacrifice. Bone density was measured in a 500 microm wide mineralized zone lateral to the implant.

RESULTS

Alkaline phosphatase levels in groups 2 and 3 (P > 0.05) were statistically higher than groups 1 and 4 (P < 0.05), and calcium serum levels were higher in group 2 than the other groups (P < 0.05). Regarding bone density, the data were grouped separately for cortical (zone A) and cancellous (zone B) bone. In zone A, intergroup analysis revealed no significant difference among groups (P > 0.05). However, in zone B, the animals that received estrogen administration (group 4) presented a higher bone density than groups 2 and 3 (P < 0.05).

CONCLUSION

It appears that estrogen therapy may prevent the negative influence of endogenous estrogen deficiency on bone density around titanium implants placed in ovariectomized rats.

Estrogen Deficiency Affects Bone Healing Around Titanium Implants: A Histometric Study in Rats

The purpose of this study was to evaluate the influence of an estrogen-deficient state on bone around titanium implants placed in rats. Thirty female Wistar rats were divided into 2 groups: test (n = 15), ovariectomized rats (OVX); and control (n = 15), sham-operated rats. Screw-type titanium implants were placed bilaterally in rats 21 days after ovariectomy or sham surgery. After 60 days, the animals were killed and undecalcified sections obtained. Blood samples were collected to obtain serum levels of alkaline phosphatase at the time of killing. Bone-to-implant contact (BIC), bone area (BA) around the implants, and bone density (BD) in a 500 microns-wide zone lateral to the implant were obtained and arranged separately for the cortical (zone A) and cancellous (zone B) regions. In zone A, there was no significant difference between test and control groups regarding BIC and BD (P > 0.05). A lower BA was observed in the estrogen-deficient animals (P < 0.05). In zone B, data analysis showed that estrogen deficiency could result in a lower percentage of BIC, BA, and BD (P < 0.05). In addition, a higher concentration of alkaline phosphatase was observed for the test group. An estrogen-deficient state could affect bone healing and bone density around titanium implants placed in rats, especially in the cancellous bone area.

Norethisterone acetate in combination with estrogen: effects on the skeleton and other organs. A review

This article is focused on the use of norethisterone acetate as progestogen in hormone replacement therapy. Emphasis is made on the fact that the primary reason for adding a progestogen to hormone replacement therapy is to protect the endometrium against hyperplasia. In this paper we review data that demonstrate that hormone replacement therapy that includes norethisterone acetate has positive effects on the postmenopausal bone metabolism and that it increases bone mass more than expected and more than treatment with alendronate. All available evidence is reviewed to show that norethisterone acetate, if given in the correct dosage, does not influence serum lipids and lipoproteins in any negative way. It is furthermore shown that norethisterone acetate seems to be superior compared to other progestogens to provide optimum bleeding control and endometrial protection. Also, hormone replacement therapy combinations with norethisterone acetate efficiently alleviate hot flushes. Hormone replacement therapy and the risk of breast cancer and the role of progestogens are discussed.

The effect on bone mass and bone markers of different doses of ibandronate: a new bisphosphonate for prevention and treatment of postmenopausal osteoporosis: a 1-year, randomized, double-blind, placebo-controlled dose-finding study

The present article describes the results from a phase II dose finding study of the effect of ibandronate, a new, third generation bisphosphonate, in postmenopausal osteoporosis. One hundred and eighty postmenopausal, white women, at least 10 years past a natural menopause, with osteopenia defined as a bone mineral density (BMD) in the distal forearm at least 1.5 SD below the premenopausal mean, entered and 141 (78%) completed a 12 months randomized, double-blind, placebo-controlled study. The women received 0.25, 0.5, 1.0, 2.5, or 5.0 mg ibandronate daily or placebo. All women received a daily calcium supplementation of 1000 mg Ca2+. Bone mass and biochemical markers of bone turnover were measured every 3 months throughout the study period. The average changes in bone mass showed positive outcome in all regions in the groups receiving ibandronate 2.5 and 5.0 mg. The responses in the two groups were not significantly different, although there was a tendency toward a higher response in bone mass in the group receiving ibandronate 2.5 mg, where the increase in BMD was 4.6 +/- 3.1% (SD) in the spine (p < 0.001), 1.3 +/- 3.0% (SD) to 3.5 +/- 5.3% (SD) in the different regions of the proximal femur (p < 0.03 to p < 0.002), and 2.0 +/- 1.9% (SD) in total body bone mineral content (BMC) (p < 0.001). There was no significant changes in bone mass in the group receiving calcium (placebo) and ibandronate 0.25 mg. Dose-related responses were found in all biochemical markers of bone turnover. In average, serum osteocalcin decreased 13 +/- 14% (SD) (placebo) and 35 +/- 14% (SD) (5.0 mg). Urinary excretions of breakdown products of type I collagen decreased 35 +/- 21% (SD) (placebo) and 78 +/- 28% (SD) (5.0 mg), p < 0.001 in all groups. In conclusion, the results suggest that ibandronate treatment increases bone mass in all skeletal regions in a dose dependent manner with 2.5 mg being the most effective dose. Ibandronate treatment reduces bone turnover to premenopausal levels and is well tolerated.

Hormone replacement therapy and osteoporosis

Restoration of the osteoporotic skeleton is difficult. Factors that may aggravate the bone loss or increase the risk of fractures should be eliminated. The physician may then decide whether the patient is a candidate for one of the treatments which either stop further bone loss or increase the bone mass. The decision should be based on a variety of factors and be taken together with the patient.

The effects of gonadotrophin-releasing hormone agonists on iliac crest cancellous bone structure in women with endometriosis

The administration of gonadotrophin-releasing hormone (GnRH) analogs to premenopausal women causes hypoestrogenism and bone loss, but the effects on cancellous microstructure have not been determined. In this study we have assessed bone structure in transiliac biopsies obtained from women before and after treatment for endometriosis with GnRH analogs. Twenty-one premenopausal women were studied, paired biopsies being obtained in 13; five women received both GnRH analogs and Org OD 14 (Tibolone, Livial). Comparison of pre- and post-treatment biopsies in women treated only with GnRH analogs showed a reduction in indices related to connectivity (node-to-terminus ratio, node-to-loop strut length, p < 0.02) and increase in inversely related indices (terminus-to-terminus and node-to-terminus strut length, p < 0.03). No significant changes were seen in any of the structural indices in women receiving both GnRH and Org OD 14 therapy. Activation frequency and bone formation rate at tissue level increased in women treated with GnRH agonists alone, although this change was not statistically significant. Our results suggest that bone loss induced by GnRH analogs may be associated with adverse effects on cancellous microstructure which are unlikely to be reversed following cessation of therapy. Concurrent treatment with Org OD 14 appears to prevent these changes.

Effect of transdermal oestradiol on the haemostatic balance of menopausal women

OBJECTIVE

To determine the effect of transdermal oestrogen replacement therapy on the haemostatic balance of menopausal women.

DESIGN

Open, parallel group, prospective study.

SETTING

Three hospital-based menopause clinics.

SUBJECTS

Fifty-two postmenopausal women receiving transdermal hormone replacement therapy (Estrapak 50) for 6 months. Comparison group of 48 untreated postmenopausal women studied in parallel.

MAIN OUTCOME MEASURES

Changes in platelet number, plasma concentrations of coagulation factors and their natural inhibitors, fibrinolytic activity, and rheological parameters.

RESULTS

Estrapak 50 had no significant thrombophilic effect on any of the outcome measures.

CONCLUSION

The haemostatic balance and thus the risk of thrombosis would not appear to be upset by this dose of transdermal oestrogen.

Biochemical markers of bone turnover. II: Diagnosis, prophylaxis, and treatment of osteoporosis

Osteoporosis is a major health problem and is becoming increasingly important in our aging society. In many of the Western countries, patients with hip fracture occupy more hospital beds than patients with any other disease. Measures to combat osteoporosis are urgently needed, but the best way of doing so is uncertain. Osteoporosis prevention can be targeted at a subgroup of the population at high risk of disease. Alternatively, the intervention can be aimed at the entire population. Both preventive strategies have been proposed for osteoporotic fractures. Some researchers advocate population programs to increase weight-bearing exercise and calcium intake or to reduce smoking, but there is little direct evidence of their effectiveness. The most widespread opinion is that bone mass measurement is the most accurate predictor of fracture risk. Prediction of fracture risk may mean treatment for several years with drugs with not only effects, but also adverse effects. This encourages attempts to optimize the diagnostic procedures.

Influence of estrogen replacement therapy on endogenous calcitonin production rates

Calcitonin is now a well-accepted therapy for inhibition of bone loss, both in the first years of menopause and in established osteoporosis. However, its exact role in the pathogenesis of that disease as well as the interactions between calcitonin production and estrogen metabolism remain unsolved. In order to clarify the influence of estrogen replacement therapy (ERT) on calcitonin secretory capacity, we measured whole plasma immunoreactive calcitonin basal levels, metabolic clearance rates and production rates in a group of postmenopausal women, before and after a daily intake for 28 days of 0.625 mg/day of conjugated equine estrogens, and again 4 weeks after the withdrawal of that estrogen replacement therapy. No significant changes appeared in immunoreactive calcitonin or immunoreactive calcitonin metabolic clearance rate but the production rate significantly increased over the 28 days (mean +/- SEM, from 21.3 +/- 5.1 pg/ml to 25.2 +/- 5.9 pg/ml, p less than 0.05), and then decreased 4 weeks after therapy was withdrawn to the initial level (17.9 +/- 3.6 pg/ml). We concluded that estrogen replacement therapy significantly increases calcitonin secretory capacity. This confirms the interactions between calcitonin production and estrogen metabolism, and may provide an explanation concerning the mode of action of estrogen replacement therapy in prevention of postmenopausal bone loss.

Hormonal prevention and treatment of osteoporosis--state of the art 1990

Osteoporosis is a growing disease, and attention should be directed to possible means of preventing and treating this disease. Osteoporosis may be caused by a number of diseases (secondary osteoporosis), but it most often occurs in otherwise healthy persons. The major risk factors are a low bone mass at skeletal maturity, and a rapid bone loss. Postmenopausal bone loss may be prevented by hormone replacement therapy. All types of oestrogens and all administration forms are effective, as long as a sufficient serum concentration is obtained. The greatest benefit of hormone replacement therapy is obtained if instituted right after the menopause, when the bone loss is most rapid. But oestrogen will also arrest the bone loss when instituted much later in life.

Time-dependent variations in bone turnover parameters during 2 months' cyclic treatment with different doses of combined estrogen and progestogen in postmenopausal women

We determined the time-dependent variations in biochemical estimates of bone resorption and bone formation in 30 healthy postmenopausal women treated for two consecutive cycles of 28 days with a sequential estrogen/gestagen therapy. The women received either 1, 2, or 4 mg estradiol (E2) for 22 days and 1 mg norethisterone acetate (NETA) from day 13 to 22 of each cycle. Blood samples were drawn twice a week, ie, 16 blood samples in each woman. Biochemical estimates of bone resorption (fasting urinary hydroxyproline/creatinine, fasting urinary calcium/creatinine) decreased significantly during the two treatment cycles. In contrast, there was no overall decrease in bone formation parameters (plasma bone Gla protein [pBGP], serum alkaline phosphatase), and serum alkaline phosphatase decreased significantly during the estrogen-only phase, but increased during the E2 plus NETA phase. The present study supports our previous suggestion that NETA stimulates bone formation in early postmenopausal women.

Hormonal replacement therapy and the skeletal system

The two most important risk factors for maintaining skeletal health are the bone mass obtained at skeletal maturity (peak bone mass) and the subsequent bone loss. Those women with a low peak bone mass and a rapid bone loss are thus at increased risk of developing osteoporosis in the future, and should be identified. This may be accomplished by determination of the bone mass combined with an estimate of the rate of the postmenopausal bone loss. The bone mass can be accurately assessed in the forearm by single photon absorptiometry. The postmenopausal bone loss can be estimated by three or four biochemical markers of bone turnover. The women at highest risk of developing osteoporosis should be offered preventive therapy, e.g., hormonal replacement therapy (HRT). HRT arrests the bone loss not only in early, but also in elderly postmenopausal women. The effect lasts as long as the therapy is continued. Several epidemiological studies have demonstrated that HRT decreases the number of osteoporotic fractures.

Calcitonin, estradiol, and hydroxyproline as parameters in the early diagnosis of involutional osteoporosis. The importance of the "second calcitonin phenomenon"

Bone metabolism was studied in a group of 92 subjects. A greater age-related decrease in calcitonin and estradiol concentrations exists in women than in men, though this difference was not significant; it was significant, however, when the values of the three different groups of women were compared. We present what we have called the second calcitonin phenomenon, that is, a highly significant difference in women between a second basal calcitonin level and the primary admission value. In the calcium infusion test, men considered to be osteoporotic showed a deceleration in the rapid loss of reserve calcitonin deposits.

Effects of conjugated equine oestrogens with and without the addition of cyclical norgestrel on serum and urine electrolytes, and the biochemical indices of bone metabolism and liver function

Serum and urine electrolytes, and biochemical indices of bone metabolism and liver function were measured in 51 post-menopausal women treated with two hormone replacement therapy regimens for 24 wk. Twenty-six of the women were treated continuously with conjugated equine oestrogens (0.625 mg/day) and the remainder were treated as above with the addition of norgestrel (0.15 mg/day) during the last 12 days of each 28-day cycle. Both treatment regimens affected electrolytes in a similar manner. The most consistent effect was a reduction in serum sodium levels and a reduction in urinary sodium/creatinine ratios. The combined regimen appeared to have a greater effect on sodium reabsorption. Both regimens decreased all the biochemical indices of bone metabolism measured, viz serum calcium (corrected for albumin), phosphate and alkaline phosphatase and urinary calcium/creatinine and hydroxyproline/creatinine ratios. The preparations used decreased the parameters by similar amounts over the 24 wk indicating that both were equally effective in reducing bone turnover. The data suggested, however, that the combined regimen had a more profound effect on bone metabolism during the early phase of treatment. The two treatment regimens had broadly the same effects on the biochemical indices of liver function, reducing albumin levels and all the liver enzymes. Judging by these indices neither regimen had a deleterious effect on liver function. We conclude that the two hormone replacement regimens have similar effects on the biochemical indices measured, but there are subtle differences between the two treatments which merit further research.