Microgravity inhibits intestinal calcium absorption as shown by a stable strontium test

Zittermann, Armin; Heer, Martina; Caillot-Augusso, A.; Rettberg, Petra; Scheld, K.; Drummer, C.; Alexandre, Christian; Horneck, G.; Vorobiev, D.; Stehle, Peter

doi:10.1046/j.1365-2362.2000.00682.x

Cited by 55 publications

(35 citation statements)

References 31 publications

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“…It takes several weeks after a negative stimulus is given for calcitriol concentrations to decrease to a lower value (23 ). Likewise, it also takes several weeks after a positive stimulus is given for very low calcitriol concentrations to return to the physiological range (31 ), indicating that 1 blood measurement at a specific time point is sufficient to estimate the range in which circulating calcitriol concentrations will be seen over several months. It is an important finding that low circulating calcitriol concentrations also inhibit uptake of 25(OH)D into extrarenal tissues such as monocytes (32 ), indicating that extrarenal calcitriol synthesis is also limited if circulating calcitriol concentrations are low.…”

Section: Discussionmentioning

confidence: 99%

Circulating Calcitriol Concentrations and Total Mortality

Zittermann¹,

Schleithoff²,

Frisch³

et al. 2009

Clinical Chemistry

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BACKGROUND:Evidence is accumulating that vitamin D supplementation of patients with low 25-hydroxyvitamin D concentrations is associated with lower cardiovascular morbidity and total mortality during long-term follow-up. Little is known, however, about the effect of low concentrations of the vitamin D hormone calcitriol on total mortality. We therefore evaluated the predictive value of circulating calcitriol for midterm mortality in patients of a specialized heart center.

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Section: Discussionmentioning

confidence: 99%

Circulating Calcitriol Concentrations and Total Mortality

Zittermann¹,

Schleithoff²,

Frisch³

et al. 2009

Clinical Chemistry

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“…These flight data further documented how increased atrophy of bone mildly increases serum calcium and phosphorus, leading to the reductions in calcium-regulating hormones, to the poor conservation of calcium, and contributing to the negative calcium balance observed with spaceflight [17,25].…”

Section: Presence Of Additional Risk Factors For Bone Lossmentioning

confidence: 78%

Adaptation of the Skeletal System During Long-Duration Spaceflight

Sibonga

Cavanagh

Lang

et al. 2007

Clinic Rev Bone Miner Metab

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This review will highlight evidence from crew members flown on space missions >90 days to suggest that the adaptations of the skeletal system to mechanical unloading may predispose crew members to an accelerated onset of osteoporosis after return to Earth. By definition, osteoporosis is a skeletal disorder − characterized by low bone mineral density and structural deterioration − that reduces the ability of bones to resist fracture under the loading of normal daily activities. "Involutional" or agerelated osteoporosis is readily recognized as a syndrome afflicting the elderly population because of the insipid and asymptomatic nature of bone loss that does not typically manifest as fractures until after age 1 https://ntrs.nasa.gov/search.jsp?R=20080014098 2018-05-10T03:42:55+00:00Z ~60. It is not the thesis of this review to suggest that spaceflight-induced bone loss is similar to bone loss induced by metabolic bone disease; rather this review draws parallels between the rapid and earlier loss in females that occurs with menopause and the rapid bone loss in middle-aged crew members that occurs with spaceflight unloading and how the cumulative effects of spaceflight and ageing could be detrimental, particularly if skeletal effects are totally or partially irreversible.In brief, this report will provide detailed evidence that long-duration crew members, exposed to the weightlessness of space for the typical long-duration (4-6 months) mission on Mir or the International Space Station --1. Display bone resorption that is aggressive, that targets normally weight-bearing skeletal sites, that is uncoupled to bone formation and that results in areal BMD deficits that can range between 6-20% of preflight BMD; 2. Display compartment-specific declines in volumetric BMD in the proximal femur (a skeletal site of clinical interest) that significantly reduces its compressive and bending strength and which may account for the loss in hip bone strength (i.e., force to failure); 3. Recover BMD over a post-flight time period that exceeds spaceflight exposure but for which the restoration of whole bone strength remains an open issue and may involve structural alteration; and 4. Display risk factors for bone loss --such as the negative calcium balance and down-regulated calcium-regulating hormones in response to bone atrophy --that can be compounded by the constraints of conducting mission operations (inability to provide essential nutrients and vitamins).The full characterization of the skeletal response to mechanical unloading in space is not complete. In particular, countermeasures used to date have been inadequate and it is not yet known 2 whether more appropriate countermeasures can prevent the changes in bone that have been found in previous flights, Knowledge gaps related to the effects of prolonged (> 6months) space exposure and to partial gravity environments are substantial, and longitudinal measurements on crew members after spaceflight are required to assess the full impact on skeletal recovery.

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“…Although Dumond et al (33) There is controversy over the association between the concentration of 25(OH)D and Ca absorption, which could be carefully extrapolated for Sr. A number of authors have found positive correlations (13,16,21,22,31,34), whereas others have not (15,22,29,35,36). Graff et al (35) found no significant difference in fractional Ca absorption between children with and without active rickets, despite the lower 25(OH)D concentrations in the former group.…”

Section: Discussionmentioning

confidence: 99%

“…The majority of studies evaluating Sr absorption administered it only with water (6,26,27,28,29,30). Some used a standard breakfast with a known Ca content based on the selection against Sr in favor of Ca in the intestinal tract (8,28,30,31). A standard breakfast was shown to reduce the Sr FAD at each evaluation time as well as the variance within and between subjects, but the shape of the absorption curves remained unchanged (27,30).…”

Section: Discussionmentioning

confidence: 99%

“…The choice of the fasting state and administration of Sr dissolved in water could raise discussion on the modulating effect of a meal on the transit time through the stomach and intestine. On the other hand, there is a lack of uniformity in the composition of the meals applied in the various tests described in the literature (27,30,31). Furthermore, the recommendation for the therapeutic use of strontium ranelate is that it should be taken at least 2 h before any meal.…”

Section: Discussionmentioning

confidence: 99%

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Vitamin D supplementation and strontium ranelate absorption in postmenopausal women with low bone mass

Vilaça

Camargo

Rocha

et al. 2014

European Journal of Endocrinology

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Background: Strontium ranelate is used to treat osteoporosis. Calcium (Ca) and strontium (Sr) have common chemical features and are absorbed by the same pathways. Vitamin D has a main role in calcium intestinal absorption. The aim of this study was to investigate whether vitamin D status is a determinant of strontium ranelate absorption. Methods: Twenty-five patients with vitamin D deficiency (25(OH)D!50 nmol/l) and 25 with vitamin D sufficiency (25(OH)DO75 nmol/l) underwent a 4-h oral Sr overload test. Sr absorption was evaluated as the fraction of absorbed dose and the area under the curve. After the baseline overload test, the deficient patients were treated until reaching sufficient vitamin D levels (25(OH)DO75 nmol/l) and the test was repeated. Results: Changing vitamin D status from deficient to sufficient resulted in a significant increase in 1,25(OH) 2 D (24.97G 4.64!34.62G9.14 pg/ml, P!0.001) and a reduction in parathyroid hormone (73.87G37.50!58.24G20.13 pg/ml, PZ0.006). Nevertheless, no differences were found in the parameters used to evaluate Sr absorption between the vitamin D deficient and sufficient groups. In addition, vitamin D3 replacement in the deficient group did not result in enhanced Sr absorption. Conclusion: Vitamin D status did not interfere with strontium ranelate absorption. Taking into account the benefits of adequate vitamin D status in osteoporotic patients, we strongly recommend the treatment of vitamin D deficiency. However, the data demonstrate that such treatment does not enhance strontium ranelate absorption in patients with mild deficiency.

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Microgravity inhibits intestinal calcium absorption as shown by a stable strontium test

Abstract: Intestinal calcium absorption can be diminished after only three weeks of microgravity. Changes are associated with a severe suppression of circulating calcitriol levels, but are independent of exogenous vitamin D supply and serum PTH levels.

Cited by 55 publications

References 31 publications

Circulating Calcitriol Concentrations and Total Mortality

Circulating Calcitriol Concentrations and Total Mortality

Adaptation of the Skeletal System During Long-Duration Spaceflight

Vitamin D supplementation and strontium ranelate absorption in postmenopausal women with low bone mass

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