Bone loss in response to long-term glucocorticoid therapy

A number of studies have shown that an excess of glucocorticoids induces osteoporosis, but the mechanism(s) and the time course of the reduction of bone mass remain uncertain. In order to clarify this issue we carried out a longitudinal clinical and histomorphometric study of patients requiring long-term glucocorticoid treatment.In 23 patients (9 men, 10 post- and 4 premenopausal women) biochemical and bone histomorphometric investigations were carried out before and during treatment with 10–25 mg/day of prednisone. Histomorphometric analysis of bone biopsies of the iliac crest showed that the decrease of TBV (up to −27%, P < 0.001) occurs predominantly within the first 5–7 months of treatment; during the subsequent stages, which include observations after 12 months of treatment, only minor changes were observed. Therefore trabecular bone loss can be satisfactorily described by a negative exponential function. None of the other histomorphometric parameters (osteoid surfaces, resorption surfaces, etc.) showed significant changes. However, the histological features of the bone biopsies during steroid therapy, showing a virtual lack of osteoblastic activity, ruled out an increase of bone resorption. Moreover, the dynamic study of the bone formation by double tetracycline labelling showed, in a small subgroup of patients, a decrease of the apposition rates (from 0.763 ± 0.053 to 0.305 ± 0.074 μ/day (mean ± SE) after treatment).No significant changes, at any time during steroid treatment, were observed in serum alkaline phosphatase, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone or urinary calcium excretion. Serum calcium increased significantly within the first 1–2 months of therapy and then it returned to baseline. Urinary hydroxyproline excretion decreased significantly within the first 1–2 months and continued to fall throughout the treatment.Thus, both biochemical and histological findings suggest that long-term glucocorticoid therapy causes a reduction of bone turnover, that the bone loss occurs predominantly within the first 6 months of treatment and that patients with lower bone mass have a lower rate of bone loss.     

Urinary excretion of prostacyclin and thromboxane metabolites in climacteric women: effect of estrogen-progestin replacement therapy

To study the role of vasodilatory prostacyclin and vasoconstrictory thromboxane A2 in climacteric vascular instabilities, overnight urine samples were collected from sixteen women suffering from hot flushes and sweating before, during and after the six months' cyclic estradiol-desogestrel therapy as well as from ten non-climacteric control women. The urine was assayed for 6-keto-PGF1a and 2,3-dinor-6-keto-PGF1a (metabolites of prostacyclin) as well as for thromboxane B2 and 2,3-dinor-thromboxane B2 (metabolites of thromboxane A2) by means of HPLC and radioimmunoassay. No difference was seen in baseline prostaroid output between the climacteric and non-climacteric study groups. Furthermore, no relation was observed between individual prostanoid excretion and severity of vasomotor symptoms before replacement therapy. The replacement therapy abolished or markedly alleviated hot flushes and sweating, but prostanoid output did not change. Our data imply that climacteric symptoms are not accompanied by changes in the production of prostacyclin and thromboxane A2.     

Dietary isoflavones differentially induce gene expression changes in lymphocytes from postmenopausal women who form equol as compared with those who do not

Human and animal studies suggest that dietary soy isoflavones reduce cancer risk, ameliorate postmenopausal syndrome and decrease bone resorption in postmenopausal women. The capacity to form the metabolite equol from daidzein is suggested as an important modulator of response to isoflavones; this capacity depends on gut colonization with appropriate bacteria. We administered a dietary supplement containing high-dose purified soy isoflavones (genistein, 558 mg/day; daidzein, 296 mg/day; and glycitein, 44 mg/day) to 30 postmenopausal women for 84 days and collected peripheral lymphocytes at timed intervals. Using microarray analysis, we determined whether changes in gene expression associated with this treatment support existing hypotheses as to isoflavones' mechanisms of action. Expression of a large number of genes was altered by isoflavone treatment, including induction of genes associated with cyclic adenosine 3',5'-monophosphate (cAMP) signaling and cell differentiation and decreased expression of genes associated with cyclin-dependent kinase activity and cell division. We report that isoflavone treatment in subjects who have the capacity to produce equol differentially affects gene expression as compared with nonproducers, supporting the plausibility of the importance of equol production. In general, isoflavones had a stronger effect on some putative estrogen-responsive genes in equol producers than in nonproducers. Our study suggests that, in humans, isoflavone changes are related to increased cell differentiation, increased cAMP signaling and G-protein-coupled protein metabolism and increased steroid hormone receptor activity and have some estrogen agonist effects; equol-production status is likely to be an important modulator of responses to isoflavones.     

First use of the RANKL antibody denosumab in Osteogenesis Imperfecta Type VI

Osteogenesis imperfecta (OI) is a genetically heterogeneous disease leading to bone fragility. OI-VI is an autosomal-recessive form caused by mutations in SERPINF1. There is experimental evidence suggesting that loss of functional SERPINF1 leads to an activation of osteoclasts via the RANK/RANKL pathway. Patients with OI-VI show a poor response to bisphosphonates. We report on four children with OI-VI who had shown continuously elevated urinary bone resorption markers during a previous treatment with bisphosphonates. We treated these children with the RANKL antibody denosumab to reduce bone resorption. Intervention and results: Denosumab (1 mg/kg body weight) was injected s.c. every 3 months. There were no severe side effects. Markers of bone resorption decreased to the normal range after each injection. N-terminal Propeptide of collagen 1 was measured in the serum during the first treatment cycle and decreased also. Urinary deoxypyridinoline/creatinine was monitored in a total of seven treatment cycles and indicated that bone resorption reached the pre-treatment level after 6-8 weeks. Conclusion: This was the first use of denosumab in children with OI-VI. Denosumab was well tolerated, and laboratory parameters provided evidence that the treatment reversibly reduced bone resorption. Therefore, denosumab may be a new therapeutic option for patients with OI-VI.     

Long term effects of a single dose of intravenous Ibandronate

For defining the optimal regimen of a treatment of osteoporosis with an intravenous bisphosphonate one needs to know the duration of action of a single dose of the given drug. This allows us to establish the frequency by which a given dose has to be administered for obtaining a sufficient suppression of bone resorption over a longer period. In this study 1 and 2 mg Ibandronate were given as a single i.v. injection to young normal men and to healthy postmenopausal women on a free diet and with no treatment or supplements, and the markers of bone metabolism, as well as BMD, were followed for 6 months. Urinary C-telopeptides decreased by 81-95% 1 week after the injection and remained significantly decreased for 2 weeks after 1 mg Ibandronate, and for 4 months after 2 mg. In men, PTH increased by 80% at one week and remained significantly increased for 2 weeks, after 1mg and 2 mg Ibandronate. Plasma osteocalcin decreased slowly over 2 months in all 3 groups by 22%. Alkaline phosphatase showed similar, but not significant changes. In conclusion, the inhibition of bone resorption induced by 1 mg Ibandronate i.v. does not exceed 1 month and does not allow 3 month intervals in the treatment of osteoporosis, while 2 mg cover 3 months at least.     

A 12-week structured education and exercise program improved climacteric symptoms in middle-aged women

In the present study, 40- to 60-year-old women with climacteric symptoms were placed on a 12-week structured education and exercise program to ascertain the effects of this program on climacteric symptoms, quality of life (QOL), and attitude towards exercise. A total of 35 women served as subjects. Twenty women were enrolled in an educational and exercise program that involved learning about menopause and participating in physical activity at least three times a week (Group E). For comparison, the other 15 women did not participate in this program and were instructed to refrain from exercising during study period (Group C). The effects of the 12-week interventional program on climacteric symptoms, QOL, and attitude towards exercise were thereby investigated. The program demonstrated significant effects on climacteric symptoms in terms of Kupperman index and psychosomatic symptoms, especially paresthesia and nervousness. In other words, climacteric symptoms improved significantly in Group E. Furthermore, scores for QOL and attitude towards exercise improved in Group E after the 12-week program; however, these trends did not reach statistical significance. Hence, the 12-week structured education and exercise program was shown to be effective in alleviating climacteric symptoms.     

Use of a new steroid (Org OD 14) in the climacteric syndrome

A double-blind study was carried out in 60 women with climacteric symptoms: 30 women were given Org OD 14 (2.5 mg) and 30 were given a placebo to be taken daily for six weeks. The effects of the medication on the climacteric symptoms, the subjective sensations, the plasma FSH levels and endometrial histology were studied. In the treated group compared with the control group the relief or improvement of the following climacteric symptoms were recorded: perspiration, palpitations, irritability and backache. A favourable effect on the subjective sensations was noted in both groups, although no significant difference for the group which received Org OD 14 was found. At the end of the treatment with Org OD 14, the FSH levels were found to be greatly reduced in comparison with the basal values; this, however, was not the case with the placebo group. With regard to endometrial histology, no sign of hyperplasia was found in any of the patients. No relevant side effects or symptoms of estrogenic or androgenic stimulation were recorded. For the climacteric patient needing estrogen therapy, it can be concluded that Org OD 14 is an effective and innocuous medication in the doses used.     

Effect of oestrogen on the sleep,mood, and anxiety of menopausal women.

A double-blind controlled study of the effect of piperazine oestrone sulphate on sleep, depression, anxiety, and hot flushes was performed in 34 perimenopausal women. Half of the patients were given six weeks'' placebo followed by eight weeks'' oestrogen, and half remained on placebo throughout. Sleep was recorded electrophysiologically every week, and mood and anxiety were rated daily by means of visual analogue scales. Hot flushes were counted daily. Observer rating scales of anxiety and depression were complete at intervals. During the first month of active treatment the amount of intervening wakefulness in the first six hours of sleep decreased significantly more in the oestrone group than in those on placebo. Between the baseline period and the second treatment month the oestrone group showed a significantly greater decrease in the total amount of intervening wakefulness and in the frequency of awakenings. Their total amount of rapid eye movement sleep increased. Mood and anxiety improved and the number of hot flushes decreased to a similar degree in both groups. Although oestrogen did reduce the number of episodes of wakefulness in perimenopausal women complaining of insomnia, its effects on their psychological symptoms were little different to those of placebo.     

Milk basic protein promotes bone formation and suppresses bone resorption in healthy adult men

Milk contains several components effective for bone health. In the previous in vitro and in vivo studies, we have shown that milk whey protein, especially its basic protein fraction (milk basic protein [MBP]), promoted bone formation and suppressed bone resorption. This present study examines the effect of MBP on the biochemical markers of bone metabolism in healthy adult men. Experimental beverages containing MBP (300 mg of MBP a day) were given to 30 normal healthy adult men for 16 days. The serum osteocalcin concentration had increased significantly after 16 days of ingesting the experimental beverage containing MBP. Urinary cross-linked N-teleopeptides of type-I collagen (NTx) excretion had decreased significantly after 16 days of ingesting MBP. The urinary NTx excretion was related to the serum osteocalcin concentration after 16 days of ingestion. These results suggest that MBP promoted bone formation and suppressed bone resorption, while maintaining the balance of bone remodeling.     

Metabolic effects of single-dose pamidronate administration in prostate cancer patients with bone metastases

BACKGROUND: Increased osteolysis usually accompanies sclerotic bone metastases from prostate cancer. This provides a rationale for the use of bisphosphonates to treat bone pain and prevent skeletal complications. METHODS: The fasting urinary levels of calcium, hydroxyproline (OHPRO), pyridinolines (PYD), deoxypyridinolines (DPYD), collagen cross-linked N-telopeptide (NTX) and the serum values of calcium, total alkaline phosphatase and relevant bone isoenzyme, bone gla protein (BGP), carboxy-telopeptide of type I collagen (ICTP) and parathyroid hormone (PTH) were determined at baseline and on the 15th, 30th, 60th and 90th days after single-dose (90 mg) pamidronate administration in 35 consecutive prostate cancer patients with bone metastases. These biochemical indices and serum interleukin 6 (IL-6) were also measured after four days in the last consecutive 17 cases. RESULTS: PYD, DPYD and NTX showed a significant decrease lasting four weeks (p<0.01, <0.01 and <0.001, respectively). OHPRO and ICTP did not change significantly. The NTX decline was greater than that of PYD and DPYD (maximum percent decrease: -71.3, -23.1 and -28.2, respectively). Bone formation markers and serum calcium did not change significantly. Serum PTH showed a rapid initial increase followed by a slow decrease (p<0.001). DPYD and NTX patterns did not correlate with changes in bone pain. As observed in the last 17 cases, the maximum osteolysis inhibition after pamidronate occurred on the fourth day after drug infusion. Serum IL-6 levels showed a short-lived decrease preceded by a transient rise on the fourth day. CONCLUSIONS: Pamidronate is able to induce a decrease in bone resorption without significantly influencing bone formation. The maximum decrease in bone resorption occurs very early. NTX is the most sensitive bone resorption marker in bisphosphonate therapy monitoring. Changes in IL-6 but not bone resorption markers may be useful in the prediction of symptomatic response.     

Estrogen and progestin effects on urinary calcium and calciotropic hormones in surgically-induced postmenopausal women

Seventeen surgically-induced postmenopausal (PM) women were randomized to receive either 0.625 mg of conjugated estrogens (CE) daily or 150 mg of intramuscular depomedroxyprogesterone acetate (DMPA) every 3 months. Urinary calcium/creatinine ratios were significantly higher than ratios of premenopausal controls before treatment, but were lower in all patients 2 months after both types of treatment. Compared to controls, all PM patients had similar levels of serum PTH and 25 hydroxy vitamin D before and after treatment. As a group, PM patients had lower levels of 1.25-dihydroxyvitamin D. In 5 patients who had levels which were below the normal range, 3 were treated with CE and 2 received DMPA. These patients all had significant increases in 1,25-dihydroxyvitamin D after treatment. Serum calcitonin did not change with either CE or DMPA treatment. These data suggest that, while both CE and DMPA lower calcium excretion in PM women, the mechanism(s) for the effects of hormonal treatment on bone resorption remain unsettled.     

Zinc supplementation increases bone alkaline phosphatase in healthy men.

Zinc takes part in the metabolism of bone as a constituent of the matrix and as an activator of several metallo-enzymes. Animal in vitro and in vivo studies strongly suggest that zinc supplementation could stimulate bone formation and inhibit bone resorption but data in humans remain rare. The biological effects of 50 mg zinc given orally as gluconate in 20 healthy male volunteers were investigated in a 12 weeks double-blind placebo-controlled randomized trial. To investigate bone turnover, total alkaline phosphatases activity (ALP), bone specific alkaline phosphatase activity (BAPE) and BAP mass (BAP-M) concentration were measured as parameters of bone formation while urine calcium and C-terminal collagen peptide were determined as parameters of bone resorption. Samples were obtained in fasting subjects at baseline and after 6 and 12 weeks. In zinc treated subjects, a significant increase was observed at least after 12 weeks in total ALP (p < 0.01), BAP-M (p < 0.05) and BAP-E (p < 0.02). These parameters did not significantly change in the placebo group. Urine zinc/creatinine ratio significantly increased after 6 (p < 0.03) and 12 weeks (p < 0.04) in the zinc-treated group and was significantly different from the placebo group (p < 0.002). There was no significant effect of zinc supplementation on parameters of bone resorption. In conclusion, zinc supplementation at supraphysiological doses increased parameters of bone formation in healthy men while parameters of bone resorption remained unchanged.     

Dose dependent response of symptoms,pituitary, and bone to transdermal oestrogen in postmenopausal women.

The effect of the plasma oestradiol concentration on climacteric symptoms, gonadotrophin release, and bone resorption was studied in three groups of postmenopausal women given 0.025 mg, 0.05 mg, or 0.1 mg transdermal oestradiol daily. There was a dose related reduction in symptoms, plasma follicle stimulating hormone concentration, and urinary calcium and hydroxyproline excretion. The relation of the response to plasma oestradiol values was similar for each variable with an initial large reduction and little change in response to increases in the plasma oestradiol concentration above 150 pmol/l (41 pg/ml). Hormone replacement therapy producing an effect equivalent to higher oestradiol concentrations is likely to increase the risk of side effects without conferring any additional benefit.     

Efficacy and safety of a phytoestrogen preparation derived from Glycine max (L.) Merr in climacteric symptomatology: a multicentric, open, prospective and non-randomized trial.

A multicentric, open, prospective, observational and no-randomized clinical trial was carried out in Spain with 190 postmenopausal women receiving a soy preparation rich in isoflavones (PHYTO SOYA, capsules containing 17.5 mg isoflavones). The main object of the present study was to investigate its efficacy in alleviating the symptomatology derived from the lack of estrogen, mainly hot flushes, but also other symptoms such as sleep disorder, anxiety, depression, vaginal dryness, loss of libido and bone pain. Each patient received 35 mg isoflavones per day in two doses. During the four months' treatment, a statistically significant decrease in the number of hot flushes with PHYTO SOYA was experienced by 80.82% women; only 5,48% patients did not improve with the treatment. The average reduction was 47.8%, which is equivalent to 4 hot flushes. All the other studied parameters also showed a statistically significant decrease. No severe side-effects were reported and tolerance was excellent. Treatment with PHYTO SOYA resulted in a significant improvement of the symptomatology that accompanies the lack of estrogen during menopause.     

Hippuric acid and 3-(3-hydroxyphenyl) propionic acid inhibit murine osteoclastogenesis through RANKL-RANK independent pathway

Nutritional factors influence bone development. Previous studies demonstrated that bone mass significantly increased with suppressed bone resorption in early life of rats fed with AIN-93G semi-purified diets supplemented with 10% whole blueberry (BB) powder for 2 weeks. However, the effects of increased phenolic acids in animal serum due to this diet on bone and bone resorption were unclear. This in vitro and in ex vivo study examined the effects of phenolic hippuric acid (HA) and 3-(3-hydroxyphenyl) propionic acid (3-3-PPA) on osteoclastic cell differentiation and bone resorption. We cultured murine osteoclast (macrophage) cell line, RAW 264.7 cells, and hematopoietic osteoclast progenitor cells (isolated from 4-week-old C57BL6/J mice) with 50 ng/ml of receptor activator of nuclear factor κ-Β ligand (RANKL). Morphologic studies showed decreased osteoclast number with treatment of 2.5% mouse serum from BB diet–fed animals compared with those treated with serum from standard casein diet–fed mice in both RAW 264.7 cell and primary cell cultures. HA and 3-3-PPA, but not 3–4-PPA, had dose-dependent suppressive effects on osteoclastogenesis and osteoclast resorptive activity in Corning osteo-assay plates. Signaling pathway analysis showed that after pretreatment with HA or 3-3-PPA, RANKL-stimulated increase of osteoclastogenic markers, such as nuclear factor of activated T-cells, cytoplasmic 1 and matrix metallopeptidase 9 gene/protein expression were blunted. Inhibitory effects of HA and 3-3-PPA on osteoclastogenesis utilized RANKL/RANK independent mediators. The study revealed that HA and 3-3-PPA significantly inhibited osteoclastogenesis and bone osteoclastic resorptive activity.     

Antithetic effects of ryanodine and ruthenium red on osteclast-mediated bone resorption and intracellular calcium concentrations

In the process of bone remodeling, osteoclasts are responsible for resorption of bone. High levels of intracellular calcium decrease the bone resorbing activity of osteoclasts and increase detachment of osteoclasts from the bone surface. The regulatory role of intracellular calcium in bone resorption is not clearly understood. To understand this phenomenon, we studied the effects of the intracellular calcium modulators ryanodine and ruthenium red on bone resorption using the disaggregated osteoclast pit assay. Changes in intracellular calcium concentrations after treatment with these compounds were detected with the fluoroprobe fura2. With ryanodine, a significant, dose-dependent decrease in bone resorption was detected. This inhibition of bone resorption was reversible upon the removal of ryanodine. Ryanodine increased intracellular calcium concentrations, suggesting that the mechanism of inhibition by ryanodine was via alterations in intracellular stores of calcium. After treatment with ruthenium red, osteoclasts resorbed significantly more bone compared to vehicle-treated cells. This increase in bone resorption correlated with a decrease in intracellular calcium concentrations. The addition of parathyroid hormone or ruthenium red to osteoclast cultures containing ryanodine did not attenuate the decrease in bone resorption caused by ryanodine, suggesting that the mechanism of ryanodine inhibition of bone resorption may involve the “locking” of a calcium channel in an open position. © 1995 Wiley-Liss, Inc.     

A dose finding study of a super long-acting luteinizing hormone-releasing hormone analog (leuprolide acetate depot, TAP-144-SR) in the treatment of central precocious puberty. The TAP-144-SR CPP Study Group.

The effect of leuprolide acetate (D-Leu6-[des-Gly10-NH2]-LH-RH ethylamide acetate) for depot suspension (TAP-144-SR), a synthetic analog of luteinizing hormone-releasing hormone, was examined in three doses in 36 patients (34 girls, 2 boys) with central precocious puberty. TAP-144-SR was injected subcutaneously every four weeks for twelve weeks, and clinical symptoms and plasma and urinary levels of various hormones were followed every four weeks. Eleven girls given 10 micrograms/kg showed a significant decrease in peak plasma LH and FSH responses to LH-RH test, but basal plasma LH and FSH did not change significantly. In 13 patients (11 girls and 2 boys) given 30 micrograms/kg and 12 girls given 90 micrograms/kg, both basal and peak LH and FSH were significantly suppressed. Urinary excretion of LH decreased significantly in all groups except in the 10 micrograms/kg group. Urinary excretion of FSH did not change significantly in the 10 and 30 micrograms/kg groups, but it decreased significantly in the 90 micrograms/kg group. In girls, plasma and urinary estradiol also fell greatly, but the difference was insignificant except in the 90 micrograms/kg group. Regression of sexual characteristics was observed in almost half of the patients at the 12th week of the treatment. Side effects were minimal. A dose of more than 30 micrograms/kg of TAP-144-SR is effective in suppressing gonadotropins and causing improvement of clinical symptoms, and appears to be useful in treating children with central precocious puberty.     

Inhibition of Osteocyte Apoptosis Prevents the Increase in Osteocytic Receptor Activator of Nuclear Factor κB Ligand (RANKL) but Does Not Stop Bone Resorption or the Loss of Bone Induced by Unloading

Apoptosis of osteocytes and osteoblasts precedes bone resorption and bone loss with reduced mechanical stimulation, and receptor activator of NF-κB ligand (RANKL) expression is increased with unloading in mice. Because osteocytes are major RANKL producers, we hypothesized that apoptotic osteocytes signal to neighboring osteocytes to increase RANKL expression, which, in turn, increases osteoclastogenesis and bone resorption. The traditional bisphosphonate (BP) alendronate (Aln) or IG9402, a BP analog that does not inhibit resorption, prevented the increase in osteocyte apoptosis and osteocytic RANKL expression. The BPs also inhibited osteoblast apoptosis but did not prevent the increase in osteoblastic RANKL. Unloaded mice exhibited high serum levels of the bone resorption marker C-telopeptide fragments of type I collagen (CTX), elevated osteoclastogenesis, and increased osteoclasts in bone. Aln, but not IG9402, prevented all of these effects. In addition, Aln prevented the reduction in spinal and femoral bone mineral density, spinal bone volume/tissue volume, trabecular thickness, mechanical strength, and material strength induced by unloading. Although IG9402 did not prevent the loss of bone mass, it partially prevented the loss of strength, suggesting a contribution of osteocyte viability to strength independent of bone mass. These results demonstrate that osteocyte apoptosis leads to increased osteocytic RANKL. However, blockade of these events is not sufficient to restrain osteoclast formation, inhibit resorption, or stop bone loss induced by skeletal unloading.     

Anti-resorptive effect of pilose antler blood (Cervus nippon Temminck) in ovariectomized rats

Anti-bone resorption activity of pilose antler blood (Cervus nippon Temminck) were evaluated in ovariectomized Wistar rats. The rats were randomly divided into sham operated group (SHAM), ovariectomized group (OVX) and pilose antler blood treated group. The ovariectomized rats were treated with pilose antler blood orally in 4000 microl/kg daily doses for 10 weeks. Compared with SHAM group, serum 17 beta-estradiol level decreased significantly and osteocalcin level increased significantly in OVX group, indicating successful model of osteoporosis. The experiments showed that the bone mineral density of the lumbar spine and left femur in OVX group decreased remarkably compared to SHAM group but normalized by treatment with pilose antler blood. Additionally, serum levels of insulin-like growth factor-land testosterone were lower obviously in OVX group than those in SHAM group but preserved by pilose antler blood treatment. However, no obvious changes in serum levels of calcium, phosphorus, total alkaline phosphatase and osteoprotegerin were observed among three groups. These results suggested that administration of pilose antler blood was effective in alleviating osteoporosis in ovariectomized rats.     

Changes in RANKL/OPG/RANK gene expression in peripheral mononuclear cells following treatment with estrogen or raloxifene

The RANKL/OPG/RANK pathway is the key mediator of osteoclastogenesis. Mononuclear cells may be implicated in post-menopausal osteoporosis. The effect of estrogen or raloxifene on bone resorption and the expression of RANKL/OPG/RANK in peripheral blood mononuclear cells (PBMCs) was examined. Twenty-nine women with post-menopausal osteoporosis were treated with estrogen (HRT) or raloxifene for 12 months. Bone mineral density (BMD) was measured at baseline and at 12 months at the spine and hip. Serum C-terminal telopeptide (CTX) and OPG were measured at baseline and at 1, 3, 6 and 12 months. PBMCs were isolated from 17 women and changes in RANKL, OPG and RANK mRNA were determined. The effects of estrogen or raloxifene in PBMCs in vitro were also assessed. BMD increased following treatment (lumbar spine % change mean [S.E.M.]: 4.3% [0.9], p<0.001). Serum CTX decreased (6 months: -43.7% [6.0], p<0.0001). Serum OPG declined gradually (12 months: -26.4% [4.4], p<0.001). RANKL, OPG and RANK gene expression decreased (6 months: RANKL 50.0% [24.8] p<0.001, OPG: 21.7% [28] p<0.001, RANK: 76.6% [10.2] p=0.015). Changes in OPG mRNA correlated with changes in BMD (r=-0.53, p=0.027) and CTX (r=0.7, p=0.0044). Down-regulation in RANKL, OPG, RANK mRNA and reduction in bone resorption was also seen in vitro. These results suggest that the expression of RANKL/OPG/RANK in PBMCs are responsive to the slowing in bone turnover/remodeling associated with treatment with estrogen or raloxifene. Further confirmatory studies are needed.