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PubMed1996

Intestinal absorption of strontium chloride in healthy volunteers: pharmacokinetics and reproducibility.

1. The absorption kinetics of orally administered strontium chloride and its reproducibility were investigated in healthy volunteers after administering strontium either under fasting conditions (study I, n = 8) or in combination with a standardized meal (study II, n = 8). Each subject received strontium orally at day 0, 14, and 28 and intravenously at day 42. The study was performed as part of a project in which a simple clinical test for measuring intestinal calcium absorption is being developed, based on the use of stable strontium as a marker. 2. Plasma strontium concentration-time curves were analysed by noncompartment analysis and a four compartment disposition model. Within a volunteer each oral curve was fitted simultaneously with the intravenous curve, by which means a two segment model for absorption was revealed. 3. Mean absolute bioavailability of strontium was 25% without a meal and 19% with a meal, whereas the intraindividual variation was 24% and 20%, respectively. 4. Various limited sampling absorption parameters were determined in order to select a potential test parameter for measuring intestinal calcium absorption using strontium as a marker. Fractional absorption at 4 h (Fc240), obtained after co-ingestion of strontium with a meal, appeared to be the best test parameter, because it represented bioavailability well (r = 0.90).

Administration, Oral↗
PubMed2000

Increased bone strontium levels in hemodialysis patients with osteomalacia.

BACKGROUND: In this study, we report on the association between increased bone strontium levels and the presence of osteomalacia in end-stage renal failure patients treated by hemodialysis. METHODS: We performed a histologic examination and determined the strontium content and strontium/calcium ratios in bone biopsies of 100 hemodialysis patients recruited from various centers all over the world. Aside from the bone strontium concentration, the bone aluminum content was assessed. The bone zinc concentration, a nonrelevant element for bone toxicity, was also measured. RESULTS: Bone strontium levels and bone strontium/calcium ratios were increased in subjects with osteomalacia when compared with those with the other types of renal osteodystrophy. Bone strontium and bone calcium levels correlated with each other. The slope of the linear regression curve correlating these parameters was much steeper in the osteomalacic group (Y = 2.22X - 120) as compared with the other types of renal osteodystrophy (Y = 0.52X - 5.7). Within the group of patients with osteomalacia, bone strontium levels also significantly correlated with the bone aluminum content (r = 0.72, P = 0.018). No such correlation was found for the other types of renal osteodystrophy. The bone zinc concentration of subjects with normal renal function did not differ significantly from the values noted for the various types of renal osteodystrophy taken as separate groups, nor could increased bone zinc concentrations be associated with a particular bone lesion. CONCLUSIONS: Our data demonstrate an association between osteomalacia and increased bone strontium concentrations in dialysis patients. Further studies are warranted to establish whether strontium plays either a primary, secondary, or contributive role in the development of the latter type of renal osteodystrophy.

Aged↗
PubMed2002

Fluoride and strontium accumulation in bone does not correlate with osteoid tissue in dialysis patients.

BACKGROUND: Osteomalacia is now a rare disease in dialysis patients in developed countries since the withdrawal of aluminium overload. The involvement of fluoride and strontium in the pathogenesis of the disease has been suggested. The aim of this study was to investigate a possible association between osteomalacia in dialysis patients and the fluoride or strontium contents of bone. METHODS: Of 271 bone biopsies from chronic haemodialysis patients referred to our centre, we studied the nine biopsies from patients with osteomalacia. They were compared with 23 biopsies from patients with hyperparathyroidism and 24 biopsies from patients with adynamic bone disease. Histomorphometric static and dynamic indices were measured. Bone fluoride and strontium contents were measured in biopsies from haemodialysis patients, and were compared with those of control patients. RESULTS: In the nine patients with osteomalacia, we found an absence of double labelled surfaces and increased osteoid thickness. Mild aluminium overload was observed in two of the nine patients. The bone strontium content of the entire dialysis population studied was not significantly different from control values (0.023+/-0.001 vs 0.019+/-0.002% mol/mol, P=0.15). However, bone strontium level was slightly but significantly increased in patients with osteomalacia (0.030+/-0.005%), compared with both controls (0.019+/-0.002%, P<0.05) and the other bone diseases (0.021+/-0.002%, P<0.05). Bone fluoride content was significantly higher in the entire dialysis population than in the controls (0.33+/-0.04 vs 0.13+/-0.018% (g/g ash weight), P=0.04). It was increased in osteomalacic patients compared with controls and with patients having hyperparathyroidism or adynamic bone disease. There was no correlation between formation indices (OV/BV, OS/BS, Ob.S/BS) and bone fluoride or strontium content. CONCLUSIONS: We found a prevalence of osteomalacia of 3.3% in our biopsy series for chronic dialysis patients. However, although bone strontium and fluoride contents were slightly increased, no causal relationship with these individual metals and osteomalacia could be firmly established in this small number of patients. The hypothesis of strontium- or fluoride-induced osteomalacia in renal patients merits further investigation.

Bone and Bones↗
PubMed2004

The correlation between palliation of bone pain by intravenous strontium-89 and external beam radiation to linked field in patients with osteoblastic bone metastases.

We studied the correlation between the efficacy of local external beam radiotherapy and the efficacy of strontium-89 in the palliation of osteoblastic metastatic bone pain in 43 patients with cancer. All 43 had been treated with hormonal or chemotherapy according to the primary malignancies and analgetic pharmacotherapy as needed, 36 received local external beam radiotherapy as a palliative before strontium-89 injection, and all 43 were ultimately treated with strontium-89 as salvage therapy. Responses to the first strontium treatment, and to the first radiation treatment if given, were taken from patient files. Pain was evaluated by Karnofsky performance status, analgesic dosage, and duration of response to treatment translated into numeric scores on a pain duration scale and an integrated response scale. The efficacy of limited field external radiation in metastatic bone pain palliation was 80.6% versus 58.1% for strontium-89. Patients treated with both external radiation and strontium had a positive correlation of 0.4 with a probability of P = 0.0158 between the responses to the 2 treatments, indicating that response to external radiotherapy could be viewed as an indicator of strontium-89 efficacy in metastatic osteoblastic bone pain palliation in the same patient. No significant correlation was found between strontium efficacy and gender, location of metastases to weight-bearing bones, duration of hormonal therapy or chemotherapy, or type of primary neoplasm.

Bone Neoplasms↗
PubMed1985

The strontium-induced calcium-release process and its implication in contractility of skeletal muscle of Rana ridibunda.

The electrical and mechanical activities of isolated frog muscle fibres have been recorded simultaneously under conditions (chloride-free saline containing 78.5 mM strontium acetate substituting for NaCl and CaCl2) that allow the development of a tubular strontium permeability. Under voltage-clamp conditions a large part of the contraction is due to the slow inward ISr since both are inhibited by Ni (10 mM). The remaining component of contraction, which seems to be potential-dependent, is not abolished by tetracaine (40 microM) which blocks the current-dependent component. A cumulative effect of strontium, which is not observed in the presence of Ni, leads to a 60-80% reduction in contractility for an estimated [Sr]i near 3 X 10(-4) M while the ending of the contraction observed when Sr is replaced by Ba is never obtained. In contrast no cumulative effect is observed when Ca substitutes for Sr. The first evoked inward current following a caffeine contracture fails to elicit a contraction, but in Ringer 78.5 Sr, contractility is progressively restored by successive depolarizations up to an amplitude which corresponds to 25-40% of the maximum activity. In the presence of Ca instead of Sr, the restoration of contractility reaches 100%. This recovery does not occur when the inward current is blocked by Ni. After strontium loading, a calcium entry fails immediately and reversibly to induce a mechanical response while barium ions induce a progressive and irreversible block of contractility. These results suggest that the strontium entry during successive depolarizations leads to a progressive replacement of intrareticular calcium by strontium. When all the calcium ions have been substituted for by strontium ions, the contractile apparatus remains capable of being activated by intrareticular strontium.

Animals↗
PubMed1969

Strontium and quantal release of transmitter at the neuromuscular junction.

1. Previous work has shown that in calcium-free solutions nerve impulses invade the motor nerve terminals at the neuromuscular junction, but fail to release transmitter. In these conditions, strontium ions applied iontophoretically to a minute part of a junction, or to the whole muscle by bath application, restore to the nerve impulse its ability to release transmitter.2. As with calcium, the transmitter released in the presence of strontium is in the form of packages (quanta) whose release can be predicted from Poisson's Theorem.3. The mean number of quanta released by a nerve impulse increases with the concentration of strontium. Strontium is much less effective than calcium in equimolar concentrations.4. Transmitter quanta released in the presence of strontium evoke larger unit potentials than quanta released in the presence of calcium. The larger size of the Sr-unit potentials is caused by a prolongation of transmitter action, presumably due to a post-synaptic effect of strontium.5. Neuromuscular transmission was blocked in some fibres when the concentration of strontium was raised beyond 10 mM. This junctional block was presumably due to a failure in the propagation of nerve impulses.6. The post-stimulation increase in the frequency of miniature end-plate potentials, which is normally seen in calcium solutions, is also observed when calcium is substituted by strontium. The post-stimulation effect increases with the concentration of strontium.7. It is concluded that strontium can substitute for calcium in the process of quantal release of transmitter. The physico-chemical mechanism of this substitution remains unknown.

Animals↗
PubMed2005

Therapy tolerance in selected patients with androgen-independent prostate cancer following strontium-89 combined with chemotherapy.

PURPOSE: Clinicians may have reservations about using strontium-89 for the treatment of bone metastases because of concerns that it may limit future use of chemotherapy. We assessed the rate of bone marrow failure in patients with prostate cancer who had received a dose of strontium-89. PATIENTS AND METHODS: This subgroup analysis involved 34 patients with androgen-independent prostate cancer who had been given a dose of strontium-89 and six weekly doses of doxorubicin after response to induction chemotherapy. We assessed subsequent hematotoxicity in terms of bone marrow failure and the ability to tolerate additional treatments during a median of 25 months (range, 7 to 76 months) after the strontium-89 was administered. RESULTS: No patients developed bone marrow failure within 6 months of receiving strontium-89. Five (15%) of 34 patients developed bone marrow failure at a median 23 months (range, 6 to 53 months) after the strontium-89 treatment. Bone marrow biopsy performed in two of these five patients showed complete replacement of the marrow by tumor. Thirty-one patients (91%) received subsequent cytotoxic treatments at a median 11 months (range, 1 to 33 months) after the strontium-89 treatment. CONCLUSION: This analysis demonstrated that a single dose of strontium-89 combined with chemotherapy did not affect the delivery of subsequent courses of chemotherapy in a select group of patients. However, a majority of these therapies were given off protocol and were administered at a dose schedule that might be considered inappropriate or inadequate. The clinical role and safety profile of radiopharmaceuticals combined with chemotherapy in prostate cancer therapy deserve further exploration.

Aged↗
PubMed2004

Strontium ranelate improves bone resistance by increasing bone mass and improving architecture in intact female rats.

UNLABELLED: Strontium ranelate given to intact rats at doses up to 900 mg/kg/day increases bone resistance, cortical and trabecular bone volume, micro-architecture, bone mass, and total ALP activity, thus indicating a bone-forming activity and an improvement of overall bone tissue quality. INTRODUCTION: Various anti-osteoporotic agents are available for clinical use; however, there is still a need for drugs able to positively influence the coupling between bone formation and bone resorption to increase bone mass and bone strength. Strontium ranelate (PROTELOS), a new chemical entity containing stable strontium (Sr), was tested for its capacity to influence bone quality and quantity. MATERIALS AND METHODS: The long-term effects of strontium ranelate on bone were investigated in intact female rats treated with various doses of strontium ranelate (0, 225, 450, and 900 mg/kg/day) for 2 years. In a second series of experiments, the effects of 625 mg/kg/day were evaluated in intact male and female rats for the same period of time. Bone mineral mass and mechanical properties were evaluated at various skeletal sites (vertebra and femur), and bone tissue micro-architecture was evaluated by static histomorphometry at the tibio-fibular junction (cortical bone) and at the tibia metaphysis (trabecular bone). Plasma total alkaline phosphatase (ALP) activity and serum levels of insulin-like growth factor-I (IGF-I) were also assessed. RESULTS: In female rats treated with strontium ranelate over 2 years, dose-dependent increases of bone strength and bone mass of the vertebral body (containing a large proportion of trabecular bone) and of the midshaft femur (containing mainly cortical bone) were detected without change in bone stiffness. Similar effects were observed in males at the level of the vertebra. This increase in mechanical properties was associated with improvements of the micro-architecture as assessed by increases of trabecular and cortical bone volumes and trabecular number and thickness. Finally, plasma total ALP activity and IGF-I were also increased in treated animals, compatible with a bone-forming activity of strontium ranelate. CONCLUSION: A long-term treatment with strontium ranelate in intact rats is very safe for bone and improves bone resistance by increasing bone mass and improving architecture while maintaining bone stiffness.

Animals↗
PubMed2000

Probing fundamental aspects of synaptic transmission with strontium.

Strontium is capable of supporting synaptic transmission, but release is dramatically different from that evoked in calcium. By measuring presynaptic strontium levels, we gain insight into the actions of strontium, which has implications for the identification of molecules involved in different aspects of synaptic transmission. We examined presynaptic divalent levels and synaptic release at the granule cell to stellate cell synapse in mouse cerebellar slices. We find that the prolonged duration of release and paired-pulse facilitation in the presence of strontium can be accounted for by the slower removal of strontium from the presynaptic terminal. Phasic and delayed release are both driven by strontium less effectively than by calcium, indicating that a heightened sensitivity to strontium is not a feature of the binding sites involved in facilitation and delayed release. We also find that the cooperativity for phasic release is 1.7 for strontium compared with 3.2 for calcium, suggesting that differential binding may help to identify the calcium sensor involved in phasic release.

Animals↗
PubMed1991

The effects of repeated administration of various chelating agents on the removal of strontium from the mouse.

The effects of repeated ip administration of diethylenetriaminepentaacetic acid (DTPA), Kryptofix 222, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), ethylenglycol-bis-(beta-amino-ethylether)-N,N'-tetraacetic acid (EGTA), and Kryptofix 5 on the distribution and excretion of sc-injected strontium were investigated in male Swiss mice. Groups of 20 animals received 95 mg strontium nitrate/kg, and 10 min later ip treatment with one of the chelators or 0.9% saline was initiated and continued for 10 d. The animals were housed in plastic metabolism cages, and urine and feces were collected daily during the period of treatment. At the end of this period, the animals were killed and the concentration of strontium determined in their tissues. Only Kryptofix 5 and EGTA significantly increased the amount of strontium excreted into feces, whereas none of the chelators significantly enhanced the urinary elimination of strontium. Treatment with Kryptofix 5 significantly decreased the concentration of strontium in all tissues analyzed. Kryptofix 5 was the most effective agent of those tested in the removal of strontium after a single dose of strontium nitrate.

Animals↗
PubMed2000

X-Ray Absorption Spectroscopy of Strontium(II) Coordination.

Sorption of dissolved strontium on kaolinite, amorphous silica, and goethite was studied as a function of pH, aqueous strontium concentration, the presence or absence of atmospheric CO(2) or dissolved phosphate, and aging over a 57-day period. Selected sorption samples ([Sr(aq)](i) approximately 0.5-1x10(-3) m) were examined with synchrotron X-ray absorption spectroscopy (XAS) at low (13-23 K) and room temperatures to determine the local molecular coordination around strontium. Quantitative analyses of the extended X-ray absorption fine structure (EXAFS) of kaolinite, amorphous silica, and most goethite sorption samples showed a single first shell of 9-10 (+/-1) oxygen atoms around strontium at an average Sr-O bond-distance of 2.61 (+/-0.02) Å, indicating hydrated surface complexes. The EXAFS spectra were unchanged after reaction for up to 57 days. Likewise, in kaolinite sorption samples prepared in 100% nitrogen atmosphere, the presence of dissolved phosphate (0.5x10(-3) m) in addition to strontium did not change the local coordination around strontium. In two goethite sorption samples reacted in air at pH approximately 8.5, the EXAFS spectra (collected at low and room temperature) clearly showed that the local structure around strontium is that of strontianite (SrCO(3)(s)). We also noted an increase in strontium uptake on goethite in the presence of atmospheric CO(2) in batch experiments, relative to CO(2)-free experiments. These observations suggest that sorption of carbonate may nucleate the precipitation of SrCO(3) in the pH range in which carbonate sorption on goethite is near a maximum. At higher pH, carbonate surface sorption decreases as dissolved CO(2) decreases. For goethite sorption samples above pH 8.6, hydrated surface complexes, rather than a precipitate, were observed in the EXAFS spectra. Copyright 2000 Academic Press.

Journal Article↗
PubMed2005

Strontium ranelate: a new treatment for postmenopausal osteoporosis with a dual mode of action.

In vitro, strontium ranelate increases collagen and noncollagen protein synthesis by mature osteoblast-enriched cells. Its effects on bone formation were confirmed as the drug enhanced preosteoblastic cell replication. In the isolated osteoclast, preincubation of bone slices with strontium ranelate-induced dose-dependent inhibition of the bone-resorbing activity of treated rat osteoclast. Strontium ranelate dose-dependently inhibited preosteoclast differentiation. Its effect in postmenopausal women with established osteoporosis was assessed during an international, prospective, double-blind, randomized, placebo-controlled phase 3 program comparing strontium ranelate 2 g daily with placebo. The 3-year analysis of the phase 3 study, Spinal Osteoporosis Therapeutic Intervention, evaluating the effect of strontium ranelate 2 g/day on vertebral fracture rates, revealed a significant 41% reduction in the relative risk of patients experiencing new vertebral fracture with strontium ranelate over 3 years. A second phase 3 study showed a significant reduction in the relative risk of experiencing a nonvertebral fracture in the group treated with strontium ranelate over 3 years. These results show that strontium ranelate is a new, effective, and safe treatment for vertebral and hip osteoporosis, with a unique mode of action, increasing bone formation and decreasing bone resorption leading to a rebalance of bone turnover in favor of bone formation.

Animals↗
PubMed2006

Strontium ranelate: a physiological approach for optimizing bone formation and resorption.

Osteoporosis associated with estrogen deficiency results from an imbalance between bone resorption and formation, causing deterioration of bone architecture and decreased bone mass. Anti-osteoporotic therapies that have been developed so far include either anticatabolic or anabolic drugs. Strontium ranelate is a newly developed drug that induces opposite effects on bone resorption and formation. This dual original mode of action was demonstrated in experimental studies on bone cells and pharmacological studies in animals. In vitro, strontium ranelate was shown to decrease bone resorption. This effect resulted from a decreased differentiation and resorbing activity of osteoclasts and increased osteoclast apoptosis. In contrast, strontium ranelate was shown to enhance preosteoblastic cell replication and collagen synthesis in culture without affecting bone mineralization. In vivo, strontium ranelate promoted bone formation and reduced bone resorption in intact mice, an effect which resulted in increased vertebral bone mass. Additionally, strontium ranelate was found to reduce resorption and long bone loss induced by hind limb immobilization in rats. Finally, strontium ranelate administration decreased bone resorption and maintained bone formation in adult ovariectomized rats, which resulted in prevention of bone loss. In clinical trials (Spinal Osteoporosis Therapeutic Intervention [SOTI]), bone alkaline phosphatase levels increased, whereas C cross-linking telopeptide of type I collagen (CTX) levels decreased in patients treated with strontium ranelate compared with placebo at all time points. These pharmacological and clinical studies suggest that strontium ranelate acts by increasing bone formation and decreasing bone resorption and that these effects result in improved bone mass in vivo.

Animals↗
PubMed2006

Strontium ranelate: a physiological approach for an improved bone quality.

In vitro studies have suggested that strontium ranelate enhances osteoblastic cell replication leading to an increase in bone-forming activity. Simultaneously, strontium ranelate dose dependently decreases osteoclastic activity. In vivo studies indicate that strontium ranelate decreases bone resorption and maintains a high bone formation and prevents bone loss. This positive uncoupling between bone formation and bone resorption results in bone gain and improvement in bone geometry and microarchitecture in growing animals. In intact female rats, a 2-year period of exposure to strontium ranelate significantly increased bone mechanical properties of vertebrae and midshaft femur. All the determinants of bone strength were positively influenced by the treatment like bone mass, dimension, microarchitecture, and intrinsic bone tissue quality. The increment in bone mechanical properties was characterized by an increase in maximal load but also by a dramatic improvement in energy to failure, which was essentially due to an increment in plastic energy. Such modifications observed with strontium ranelate treatment are in good agreement with the improvement in intrinsic bone quality. These results strongly suggest that new bone formed following strontium ranelate treatment is able to withstand greater deformation before fracture. Furthermore, treatment with strontium ranelate prevents the deleterious effect of ovariectomy on bone strength. In this model, a 1-year period of exposure to strontium ranelate significantly prevents alteration of bone mechanical properties of vertebrae in association with a partial preservation of the trabecular microarchitecture: a dose-dependent effect on the bone volume/trabecular volume ratio and trabecular number and thickness.

Animals↗
PubMed2006

Short-term hemostatic safety of strontium ranelate treatment in elderly women with osteoporosis.

BACKGROUND: Strontium ranelate offers significant clinical benefits in terms of efficacy, tolerability, and ease of administration in the treatment of postmenopausal osteoporosis. However, there are some data revealing an association between strontium ranelate treatment and increased incidence of venous thromboembolism (VTE), suggesting possible adverse prothrombotic effects of the drug. OBJECTIVE: To assess the effect of strontium ranelate treatment on primary hemostasis, secondary hemostasis, and the natural anticoagulant defense system, together with prothrombotic markers, in elderly women with osteoporosis. METHODS: This study was designed in a prospective manner. Thirty-five elderly women diagnosed with osteoporosis were included. During a 2 month treatment period, participants received strontium ranelate 2 g. Platelet Function Analyzer-100 (PFA-100) in vitro bleeding time was performed to depict primary hemostasis. Secondary hemostatic parameters including prothrombin time, international normalized ratio, activated partial thromboplastin time, anti-cardiolipine immunoglobulin (Ig) M and IgG, antiphospholipid IgM and IgG, protein C, protein S, antithrombin III, lupus anticoagulant, fibrinogen, thrombin, activated protein C resistance, and plasma levels of d-dimer were assessed. These parameters were tested before and after 2 month treatment with strontium ranelate. RESULTS: Mean +/- SD age of the patients was 72.82 +/- 5.69 years. After 60 days of treatment, there was no statistically significant prolongation in PFA-100 in vitro bleeding time and no statistically significant change in the critical hemostatic parameters in patients receiving strontium ranelate that led to discontinuation of the treatment. None of the subjects developed clinical VTE during the 2 month period of strontium ranelate treatment. CONCLUSIONS: The hemostatic safety of strontium ranelate in the elderly population with osteoporosis was shown over 2 months of treatment; however, its long-term hemostatic safety should be evaluated further.

Aged↗
PubMed2002

[In vitro study on the cytotoxicity of strontium substituted hydroxyapatite].

OBJECTIVE: To evaluate the cytotoxicity of strontium substituted hydroxyapatite. METHODS: Cell Relative Growth Rate(RGR) method, MTT assay and Flow Cytometry(FCM) method were used, and the strontium substituted hydroxyapatite contained different strontium concentration(0%,1%,5%,10%,100%). RESULTS: It was found that there's no apparent cytotoxicity of all the strontium substituted hydroxyapatite,but the cytotoxicity increased as the strontium concentration raised. As the FCM method appeared, there was no apparent difference between the pure hydroxyapatite and 1%,5% strontium substituted hydroxyapatite. CONCLUSION: Strontium substituted hydroxyapatite has good biocompatibility, and 10%,100% strontium substituted hydroxyapatite has weak cytotoxicity.

English Abstract↗
PubMed1986

Bone chemistry and prehistoric diet: strontium studies of laboratory rats.

Strontium analysis of prehistoric human bone for the reconstruction of past diets is a relatively new technique in anthropology. In order to evaluate certain assumptions of the method, diets with low and high levels of strontium were fed to male, virgin female, and pregnant female laboratory rats. Analysis of the femurs of these rats by inductively coupled plasma/atomic emission spectrometry indicates that dietary intake is directly reflected in levels of strontium in bone ash. When dietary strontium levels were low, the observed ratio for bone:diet in the laboratory rats averaged 0.26, a value similar to that observed by other investigators. Among the groups fed high levels of strontium, pregnant females accumulated the most and virgin females accumulated the least strontium in bone. Males were intermediate. Gender differences in bone strontium among prehistoric human populations are considered in these terms.

Animals↗
PubMed1995

[Determination of intestinal strontium absorption--assessment and validation of routinely manageable test procedures].

Intestinal strontium absorption has been discussed recently as an indirect measure for calcium uptake. Prerequisite for the clinical use of an oral strontium test is the availability of a reliable procedure including controlled strontium supply, sample pretreatment and analysis as well as the assessment of normal values. In the present study, a group of young females (n = 33; 24.0 +/- 2.7 y; BMI 21.5 +/- 1.9) received an oral dose of 2.27 mmol strontium in a standardized breakfast that contained 0.625 mmol calcium. Before and 220 min after the bolus serum strontium concentrations were determined by means of atomic absorption spectrophotometry (coefficient of variation: within day 4.8%, n = 10; day-to-day 9.5%, n = 8). The error of the method was 2.7%. Calculation of the fractional strontium absorption rate considered the respective distribution volume (extracellular fluid; either estimated using body weight or determined by means of bioimpedance analysis [BIA]). Average absorption rates were 13.3 +/- 3.1% and, considering BIA measurement 13.6 +/- 2.6%, respectively. Smoking, exercise and, use of oral contraceptives showed no effects. Our oral strontium test is characterized by excellent reliability, easy handling and low costs and, thus, is suitable for routine use.

Administration, Oral↗