Magnesium and Fracture Risk in the General Population and Patients Receiving Dialysis: A Narrative Review.

Purpose of Review: Magnesium is an essential mineral for bone metabolism, but little is known about how magnesium intake alters fracture risk. We conducted a narrative review to better understand how magnesium intake, through supplementation, diet, or altering the concentration of dialysate magnesium, affects mineral bone disease and the risk of fracture in individuals across the spectrum of kidney disease. Sources of Information: Peer-reviewed clinical trials and observational studies. Methods: We searched for relevant articles in MEDLINE and EMBASE databases. The methodologic quality of clinical trials was assessed using a modified version of the Downs and Black criteria checklist. Key Findings: The role of magnesium intake in fracture prevention is unclear in both the general population and in patients receiving maintenance dialysis. In those with normal kidney function, 2 meta-analyses showed higher bone mineral density in those with higher dietary magnesium, whereas 1 systematic review showed no effect on fracture risk. In patients receiving maintenance hemodialysis or peritoneal dialysis, a higher concentration of dialysate magnesium is associated with a lower concentration of parathyroid hormone, but little is known about other bone-related outcomes. In 2 observational studies of patients receiving hemodialysis, a higher concentration of serum magnesium was associated with a lower risk of hip fracture. Limitations: This narrative review included only articles written in English. Observed effects of magnesium intake in the general population may not be applicable to those with chronic kidney disease particularly in those receiving dialysis.

Justification: Le magnésium est un minéral essentiel pour le métabolisme osseux, mais on en sait peu sur la façon dont un apport en magnésium modifie le risque de fracture. Nous avons procédé à un examen narratif afin de mieux comprendre comment les maladies liées à la densité minérale osseuse et le risque de fracture sont affectés par un apport en magnésium (supplémentation, régime alimentaire ou modification de la concentration de dialysat de magnésium) chez les personnes atteintes d'insuffisance rénale. Sources: Essais cliniques et études observationnelles examinés par des pairs. Méthodologie: Nous avons répertorié les articles pertinents dans les bases de données MEDLINE et EMBASE. Une version modifiée des critères de contrôle de la qualité des études de Downs et Black a servi à évaluer la qualité méthodologique des essais cliniques retenus. Principaux résultats: Le rôle d'un apport en magnésium dans la prévention des fractures n'est pas clair, tant dans la population générale que chez les patients sous dialyse d'entretien. Chez les personnes ayant une fonction rénale normale, deux méta-analyses ont montré que les personnes dont le régime alimentaire est riche en magnésium présentent une densité minérale osseuse plus élevée; alors qu'une revue systématique n'a montré aucun effet sur le risque de fracture. Chez les patients sous hémodialyse d'entretien ou dialyse péritonéale, une concentration plus élevée de dialysat de magnésium est associée à une plus faible concentration d'hormone parathyroïdienne, mais on en sait peu sur les autres effets liés aux os. Dans deux études observationnelles portant sur des patients sous hémodialyse, une concentration plus élevée de magnésium sérique a été associée à un risque plus faible de fracture de la hanche. Limites: Cet examen narratif ne comprend que des articles rédigés en anglais. Il est possible que les effets d'un apport en magnésium observés dans la population générale ne puissent s'appliquer aux personnes atteintes d'une néphropathie chronique, en particulier aux personnes sous dialyse.

A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review.

PURPOSE OF REVIEW: Strategies to mitigate muscle cramps are a top research priority for patients receiving hemodialysis. As hypomagnesemia is a possible risk factor for cramping, we reviewed the literature to better understand the physiology of cramping as well as the epidemiology of hypomagnesemia and muscle cramps. We also sought to review the evidence from interventional studies on the effect of oral and dialysate magnesium-based therapies on muscle cramps. SOURCES OF INFORMATION: Peer-reviewed articles. METHODS: We searched for relevant articles in major bibliographic databases including MEDLINE and EMBASE. The methodological quality of interventional studies was assessed using a modified version of the Downs and Blacks criteria checklist. KEY FINDINGS: The etiology of muscle cramps in patients receiving hemodialysis is poorly understood and there are no clear evidence-based prevention or treatment strategies. Several factors may play a role including a low concentration of serum magnesium. The prevalence of hypomagnesemia (concentration of <0.7 mmol/L) in patients receiving hemodialysis ranges from 10% to 20%. Causes of hypomagnesemia include a low dietary intake of magnesium, use of medications that inhibit magnesium absorption (eg, proton pump inhibitors), increased magnesium excretion (eg, high-dose loop diuretics), and a low concentration of dialysate magnesium. Dialysate magnesium concentrations of ≤0.5 mmol/L may be associated with a decrease in serum magnesium concentration over time. Preliminary evidence from observational and interventional studies suggests a higher dialysate magnesium concentration will raise serum magnesium concentrations and may reduce the frequency and severity of muscle cramps. However, the quality of evidence supporting this benefit is limited, and larger, multicenter clinical trials are needed to further determine if magnesium-based therapy can reduce muscle cramps in patients receiving hemodialysis. In studies conducted to date, increasing the concentration of dialysate magnesium appears to be well-tolerated and is associated with a low risk of symptomatic hypermagnesemia. LIMITATIONS: Few interventional studies have examined the effect of magnesium-based therapy on muscle cramps in patients receiving hemodialysis and most were nonrandomized, pre-post study designs.

CONTEXTE MOTIVANT LA REVUE: Les stratégies visant à atténuer les crampes musculaires sont parmi les principales priorités de recherche des patients hémodialysés. L'hypomagnésémie étant un possible facteur de risque, nous avons procédé à une revue de la littérature afin de mieux en comprendre l'épidémiologie, et d'examiner la physiologie et l'épidémiologie des crampes musculaires. Nous souhaitions également examiner les données probantes issues d'études interventionnelles portant sur l'effet des thérapies à base de dialysat de magnésium et de magnésium oral sur les crampes musculaires. SOURCES: Articles examinés par les pairs. MÉTHODOLOGIE: Nous avons cherché les articles pertinents dans les principales bases de données bibliographiques, notamment MEDLINE et EMBASE. La qualité méthodologique a été évaluée à l'aide d'une version modifiée des critères de contrôle de la qualité des études de Downs et Black. PRINCIPAUX RÉSULTATS: L'étiologie des crampes musculaires chez les patients hémodialysés est mal comprise et il n'existe aucune stratégie de prévention ou traitement clairement fondé sur des données probantes. Plusieurs facteurs pourraient jouer un rôle, notamment de faibles concentrations sériques de magnésium. La prévalence de l'hypomagnésémie (concentration inférieure à 0,7 mmol/L) chez les patients hémodialysés variait de 10 à 20 %. Une faible consommation de magnésium dans l'alimentation, la prise de médicaments inhibant l'absorption du magnésium (ex. les inhibiteurs de la pompe à protons), l'excrétion accrue du magnésium (ex. dose élevée de diurétiques de l'anse) et une faible concentration de dialysat de magnésium figuraient parmi les causes d'hypomagnésémie. Un taux de dialysat de magnésium inférieur ou égal à 0,5 mmol/L pourrait être associé à une diminution de la concentration sérique de magnésium au fil du temps. Les résultats préliminaires de certaines études observationnelles et interventionnelles suggèrent qu'une concentration sérique plus élevée de magnésium dans le dialysat augmenterait les concentrations sériques de magnésium et pourrait réduire la fréquence et la sévérité des épisodes de crampes musculaires. La qualité des preuves appuyant ce bienfait est cependant limitée. Des essais multicentriques et à plus vaste échelle sont nécessaires pour juger si un traitement à base de magnésium peut véritablement réduire les crampes musculaires chez les patients hémodialysés. Dans les études menées jusqu'à maintenant, l'augmentation de la concentration de dialysat de magnésium semblait bien tolérée et a été associée à un faible risque d'hypermagnésémie symptomatique. LIMITES: Peu d'études interventionnelles ont examiné l'effet de la prise de magnésium sur les crampes musculaires des patients hémodialysés, et la plupart de celles-ci constituaient des plans pré- ou post-études non randomisées.

Gabapentin dose and the 30-day risk of altered mental status in older adults: A retrospective population-based study.

Gabapentin is an effective treatment for chronic neuropathic pain but may cause dizziness, drowsiness, and confusion in some older adults. The goal of this study was to assess the association between gabapentin dosing and adverse outcomes by obtaining estimates of the 30-day risk of hospitalization with altered mental status and mortality in older adults (mean age 76 years) in Ontario, Canada initiated on high dose (>600 mg/day; n = 34,159) compared to low dose (≤600 mg/day; n = 76,025) oral gabapentin in routine outpatient care. A population-based, retrospective cohort study assessing new gabapentin use between 2002 to 2014 was conducted. The primary outcome was 30-day hospitalization with an urgent head computed tomography (CT) scan in the absence of evidence of stroke (a proxy for altered mental status). The secondary outcome was 30-day all-cause mortality. The baseline characteristics measured in the two dose groups were similar. Initiation of a high versus low dose of gabapentin was associated with a higher risk of hospitalization with head CT scan (1.27% vs. 1.06%, absolute risk difference 0.21%, adjusted relative risk 1.29 [95% CI 1.14 to 1.46], number needed to treat 477) but not a statistically significant higher risk of mortality (1.25% vs. 1.16%, absolute risk difference of 0.09%, adjusted relative risk of 1.01 [95% CI 0.89 to 1.14]). Overall, the risk of being hospitalized with altered mental status after initiating gabapentin remains low, but may be reduced through the judicious use of gabapentin, use of the lowest dose to control pain, and vigilance for early signs of altered mental status.

Higher anti-depressant dose and major adverse outcomes in moderate chronic kidney disease: a retrospective population-based study.

BACKGROUND: Many older patients have chronic kidney disease (CKD), and a lower dose of anti-depressants paroxetine, mirtazapine and venlafaxine is recommended in patients with CKD to prevent drug accumulation from reduced elimination. Using information available in large population-based healthcare administrative databases, we conducted this study to determine if ignoring the recommendation and prescribing a higher versus lower dose of anti-depressants associates with a higher risk of adverse events. METHODS: We conducted a population-based cohort study to describe the 30-day risk of delirium in older adults who initiated a higher vs. lower dose of these three anti-depressants in routine care. We defined delirium using the best proxy available in our data sources - hospitalization with an urgent head computed tomography (CT) scan. We determined if CKD status modified the association between anti-depressant dose and outcome, and examined the secondary outcome of 30 day all-cause mortality. We used multivariable logistic regression analyses to estimate adjusted odds ratios (relative risk (RR)) and 95% confidence intervals. RESULTS: We identified adults (mean age 75) in Ontario who started a new study anti-depressant at a higher dose (n=36,651; 31%) or lower dose (n=81,160; 69%). Initiating a higher vs. lower dose was not associated with an increased risk of hospitalization with head CT (1.09% vs. 1.27% (adjusted RR 0.90; 95% CI, 0.80 to 1.02), but was associated with a lower risk of all-cause mortality (0.76% vs. 0.97% RR 0.82; 95% CI, 0.71 to 0.95). Neither of these relative risks were modified by the presence of CKD (p=0.16, 0.68, respectively). CONCLUSIONS: We did not observe an increase in two adverse outcomes when study anti-depressants were initiated at a higher dose in elderly patients with moderate CKD. Contrary to our hypothesis, the 30-day risk of mortality was lower when a higher versus lower dose of anti-depressant was initiated in these patients, a finding which requires corroboration and further study.

Paraffin as oxygen vector modulates tyrosine phenol lyase production by Citrobacter freundii MTCC 2424.

The efficiency of three oxygen-vectors liquid paraffin, silicone oil and n-dodecane in the production of tyrosine phenol lyase (TPL) by Citrobacter freundii MTCC 2424 was evaluated at 4% (v/v) concentration. The liquid paraffin as oxygenvectors was found to exhibit a stimulatory effect on TPL synthesis. The liquid paraffin at 6% (v/v) resulted in 34% increase in the TPL synthesis accompanied by a 13% increase in the production of cell mass at a 10 L scale. This improvement in TPL and cell mass production in the presence of liquid paraffin can be related to the fact that liquid paraffin was capable of maintaining dissolved O2 concentration above 28% throughout the course of the fermentation. Maintenance of the dissolved O2 concentration above 28% could be viewed in terms of an adequate oxygen supply to the rapidly dividing cells of the bacterium, which in turn resulted in enhanced synthesis of TPL and cell mass.

Infective endocarditis of the tricuspid valve.

Infective endocarditis (IE) usually involves the left-sided valves, and IE involving the tricuspid valve (TV) is rare, often developing in intravenous drug users (IDU). We present a case of a 32-year-old male, an intravenous drug abuser (IDA), who presented with nonspecific septic symptoms, and was treated with TV conserving surgery. Pathological examination confirmed tissue destruction, friable thrombotic vegetations, and microorganisms in the leaflet tissue.