Urinary Magnesium Concentrations Research Articles

High plasma magnesium and phosphorus levels and their correlation with struvite urolithiasis in buffaloes

BackgroundUrolithiasis is a common urinary tract disease in buffaloes, almost exclusively affects young males, and has significant economic and production impacts. We have investigated hemato-biochemical and urinary changes in an attempt to deduce their correlation with struvite urolithiasis in buffaloes. MethodsTen male buffalo calves with obstructive urolithiasis were used. Blood samples were used for hematology and elemental analysis. Urine samples were used for physico-chemical examination, microscopy, and elemental analysis. Uroliths were subjected to chemical functional group determination using the FTIR spectroscopy. ResultsThe mean neutrophil, leukocyte, and neutrophil-to-lymphocyte ratio was significantly (p < 0.05) higher in urolithic buffaloes than in healthy controls. The mean blood calcium and magnesium concentrations were significantly (p < 0.05) lower and higher in urolithic buffaloes than in healthy controls, respectively. Mean blood phosphorus concentration and calcium-phosphorus ratio were found to be non-significantly (p > 0.05) higher and lower in urolithic buffaloes than in healthy controls, respectively. The urine pH was highly alkaline. Multiple prismatic lid-shaped crystals, along with erythrocytes, leukocytes, and epithelial cells, were found in urine. The mean urinary magnesium and phosphorus concentrations were non-significantly (p < 0.05) higher in urolithic buffaloes than in healthy controls. A positive correlation of magnesium (r = 0.864, p = 0.001) and phosphorus (r = 0.849, p = 0.002) concentrations between the blood and urine was observed in urolithic buffaloes. The FTIR spectra of uroliths were similar to those of magnesium ammonium phosphate hexahydrate, MgNH4PO4·6H2O or struvite. ConclusionThe findings suggest that high plasma magnesium and phosphorus concentrations have a positive correlation with struvite urolithiasis in buffaloes.

Food groups consumption and urinary metal mixtures in women from Northern Mexico

ObjectiveWe aimed to evaluate the association between food groups and mixtures of urinary metal concentrations in a sample of women; as well as identify the most important metals within each mixture. MethodsThis is a cross-sectional analysis between food groups consumption and mixtures of various metals in urine from 439 women, ≥18 years old, from Northen Mexico. We estimated the dietary intake of 20 food groups through a validated semi-quantitative food frequency questionnaire. Urinary metal concentration of aluminum, antimony, arsenic, barium, cadmium, cesium, chromium, cobalt, copper, lead, manganese, magnesium, molybdenum, nickel, selenium, thallium, tin, vanadium, and zinc, were measured by inductively coupled plasma triple quad. We used weighted quantile sum (WQS) regression with binomial family specification to assess the association of food groups and metal mixtures, as well as to identify the most important ones. ResultsWe identified tin, lead, and antimony as the most important metals, in the metal mixtures that were positively associated with the consumption of eggs, non-starchy vegetables, fruits, seafood, corn, oil seeds, chicken, soda, legumes, red and/or processed meats, as well as negatively with the consumption of alliums, corn tortillas and/or vegetable oils. ConclusionOur findings suggest that food consumption is related to more than one metal in the study sample, and highlights the presence of some of them. Further research is required to identify the possible sources of metals in food, as well as the chronic adverse health effects attributed to their simultaneous presence.

The Association Between Essential Metal Element Mixture and Sleep Quality in Chinese Community-Dwelling Older Adults.

Previous studies have related single essential metal elements (EMEs) to sleep quality among older adults, however, the association of the EME mixture with sleep quality remained poorly understood. This study aimed to investigate the relationships between single EMEs and the EME mixture and sleep quality in older adults living in Chinese communities. This study consisted of 3957 older adults aged 60years or over. Urinary concentrations of cobalt (Co), vanadium (V), selenium (Se), molybdenum (Mo), strontium (Sr), calcium (Ca), and magnesium (Mg) were detected using inductively coupled plasma mass spectrometry. Sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). The associations of single EMEs and EME mixture with sleep quality were assessed using logistic regression and Bayesian kernel machine regression (BKMR) models, respectively. Adjusted single-element logistic regression models showed that Mo (OR = 0.927, 95%CI:0.867-0.990), Sr (OR = 0.927, 95%CI:0.864-0.994), and Mg (OR = 0.934, 95%CI:0.873-0.997) were negatively related to poor sleep quality. BKMR models exhibited similar results. Also, higher levels of the EME mixture in urine were inversely related to the odds of poor sleep quality after adjustment for covariates, and Mo had the largest conditional posterior inclusion probability (condPIP) value in the mixture. Mo, Sr, and Mg were negatively related to poor sleep quality, separately and as the mixture. The EME mixture in urine was associated with decreased odds of poor sleep quality in older adults, and Mo was the greatest contributor within the mixture. Additional cohort research is warranted to clarify the relationship of multiple EMEs with sleep quality.

Increasing Phosphorus Intake Reduces Urinary Concentrations of Magnesium and Calcium in Adult Ovariectomized Cats Fed Purified Diets

We assessed the phosphorus requirement of adult cats and the relationship between phosphorus intake and the fecal and urinary excretion of calcium, magnesium and phosphorus. Female cats (ovariectomized at the onset of sexual maturity) were fed purified diets containing 4.6, 9.2, 18.4 or 27.7 mmol phosphorus/MJ in a 4 × 4-wk crossover study. During the experiment, balance studies were performed and blood samples were taken. A dietary level of 4.6 mmol phosphorus/MJ was found to be sufficient to maintain phosphorus balance and normal plasma concentrations of phosphorus in the adult ovariectomized cats. Increasing levels of dietary phosphorus in the form of NaH2PO4·2H2O caused lower urinary pH values, lower urinary concentrations of calcium and magnesium, and higher urinary concentrations of phosphorus. When dietary levels of phosphorus were raised, the percentage of apparent absorption of magnesium was lower, whereas that of phosphorus was higher. Although it could be predicted that dietary phosphorus levels higher than the National Research Council recommendation of 9.2 mmol/MJ markedly reduced urinary struvite saturation, these higher levels are discouraged because they are associated with lower plasma phosphorus concentrations and creatinine clearance.

Post-collection acidification of spot urine sample is not needed before measurement of electrolytes

IntroductionKidney stone formers can have higher oxalate and phosphate salt amounts in their urine than healthy people and we hypothesized that its acidification may be useful. The study aims to compare results of urine concentrations of calcium, magnesium, and inorganic phosphorus in the midstream portion of first voided morning urine samples without (FMU) and with post-collection acidification (FMUa) in kidney stone patients.Materials and methodsThis is a prospective single center study. A total of 138 kidney stone patients with spot urine samples were included in the study. Urine concentrations of calcium, magnesium and inorganic phosphorus were measured with and without post-collection acidification. Acidification was performed by adding 5 µL of 6 mol/L HCl to 1 mL of urine.ResultsThe median age (range) of all participants was 56 (18-87) years. The median paired differences between FMU and FMUa concentrations of calcium, magnesium, and inorganic phosphorus were: - 0.040 mmol/L, 0.035 mmol/L, and 0.060 mmol/L, respectively. They were statistically different: P < 0.001, P < 0.001, P = 0.004, respectively. These differences are not clinically significant because biological variations of these markers are much higher.ConclusionsNo clinically significant differences in urinary calcium, magnesium, and inorganic phosphorus concentrations between FMU and FMUa in patients with kidney stones were found.

Estimating 24-hour urinary excretion using spot urine measurements in kidney stone formers.

ABSTRACTBackgroundOne limitation of the use of 24-hour collection is impracticality. We analysed the performance of spot urine measurements to estimate 24-hour excretion in patients with kidney stones.MethodsA total of 74 adult patients from two centres performed a 24-hour urine collection. A sample of the last micturition was sent for spot urine analysis. Twenty patients were asked to collect two additional spot urine samples, one before dinner and the other after dinner. Urinary concentrations of creatinine, calcium, oxalate, uric acid, citrate and magnesium were measured in the 24-hour and each of the spot urine samples. Four approaches were used to estimate 24-hour urinary excretion, multiplying the ratio of the spot urinary analyte to creatinine concentration by (i) measured 24-hour urinary creatinine excretion (Prediction 1), (ii) estimated 24-hour urinary creatinine excretion (Prediction 2), (iii) assumed 1-g 24-hour urinary creatinine excretion (Prediction 3) or (iv) assumed 1.5-g 24-hour urinary creatinine excretion (Prediction 4). For each parameter we computed Lin's concordance correlation coefficients (CCCs), Bland–Altman plots and 95% limits of agreement.ResultsThe performance of estimates obtained with Prediction 1 and Prediction 2 was similar, except for citrate and uric acid, for which Prediction 2 performed worse. Both approaches performed moderately well: citrate CCC {0.82 [95% confidence interval (CI) 0.75–0.90]}, oxalate [0.66 (95% CI 0.55–0.78)], magnesium [0.66 (95% CI 0.54–0.77)], calcium [0.63 (95% CI 0.50–0.75)] and uric acid [0.52 (95% CI 0.36–0.68)]. The performance of Predictions 3 and 4 was worse.ConclusionsAlthough spot urine samples may hold promise for clinical and population-based research, at present they have limited utility in clinical practice. Measuring or estimating 24-hour creatinine, rather than assuming a given creatinine excretion, will be necessary in future studies of spot urine samples.

The Effects of Magnesium Supplementation on Serum Magnesium and Calcium Concentration in Patients With Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

The aim of this systematic review and meta-analysis was to summarize all the existing randomized controlled trials (RCTs) evidence and to evaluate the effects of magnesium supplementation on serum magnesium, calcium and urinary magnesium concentrations in patients with type 2 diabetes compared with the control. Two independent authors systematically searched online databases including Embase, Scopus, PubMed, and Web of Science from inception until 30th January 2022. RCTs complying with the inclusion criteria were included in this meta-analysis. The heterogeneity among the included studies was assessed using Cochrane’s Q test and I-square (I2) statistic. Data were pooled using a random-effects model and weighted mean difference (WMD) was considered as the overall effect size. Sixteen trials were included in this meta-analysis. Serum magnesium (mean difference, 0.15 mg/dL; 95% confidence interval [CI], 0.06 to 0.23; p = 0.001) and urinary magnesium (WMD, 1.99 mg/dL; 95% CI, 0.36 to 3.62; p = 0.017) concentrations were significantly increased after magnesium supplementation when compared with the control group. However, magnesium supplementation did not have any significant effect on serum calcium (WMD, −0.09 mg/dL; 95% CI, −0.27 to 0.08; p = 0.294) level when compared with the control group. This meta-analysis demonstrated that magnesium supplementation significantly increased Serum magnesium levels which may have played an indirect role in improved clinical symptoms in patients with type 2 diabetes.

Urinary magnesium predicts risk of cardiovascular disease in Chronic Kidney Disease stage 1–4 patients

Observational studies on dietary or circulating magnesium and risk of cardiovascular disease (CVD) in Chronic Kidney Disease (CKD) stage 1-4 have reported no-to-modest inverse associations. 24 h Urinary magnesium concentration (24h UMg), an indicator of intestinal magnesium absorption, may provide better insight into the connection of CKD progression. We examined 3179 participants aged 18-74 years with CKD stage 1-4 in the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE) study, a prospective population-based cohort study. Data were analysed using Spearman rank-order correlation coefficients for all comparisons. We also performed a time-to-event analysis of the data using the Kaplan-Meier survival model, Cox proportional hazard model and competing risk Fine and Gray subdistribution hazard model. During a median follow-up of 4.19 years (interquartile range, 3.43-5.09 years), when modelling end-stage renal disease (ESRD), CVD and death, 24h UMg was associated with risk of CVD (HR, 1.612 (95% CI, 1.056-2.460)), while no significant association with ESRD and death endpoints could be detected. 24 h UMg risk variants display a modest association with CVD in CKD stage 1-4 patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03041987. Registered January 1, 2012. (retrospectively registered) (https://www.clinicaltrials.gov/ct2/show/NCT03041987?term=Chinese+Cohort+Study+of+Chronic+Kidney+Disease+%28C-STRIDE%29&rank=1).

Association Between Magnesium and Oxidative Stress in Patients with Obesity

Background: The role of minerals in preventing the generation of oxidative stress in obese individuals has been evaluated. Magnesium is an antioxidant nutrient and a cofactor of enzymes involved in the cell membrane stabilization, attenuating the effects of oxidative stress. Objective: To evaluate the association between magnesium and concentrations of thiobarbituric acid reactive substances (TBARS) in patients with obesity and eutrophic women. Methods: A cross-sectional study was conducted with 73 women, divided into two groups: case group (patients with obesity, n=27) and control group (eutrophic women, n=46). Measurements of body mass index and waist circumference were performed. Dietary magnesium intake was assessed by the three-day food record using the NutWin software. Urinary magnesium concentration was measured by atomic absorption spectrophotometry method. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were also determined. Results: Mean values of dietary magnesium intake were 161.59 ± 60.04 and 158.73 ± 31.96 for patients with obesity and control group, respectively, with no significant difference between the groups studied (p &gt;0.05). The value of urinary excretion of magnesium was lower than the reference values in both groups, with no significant difference between the groups studied (p &gt;0.05). The plasma concentration of thiobarbituric acid reactive substances was significantly higher in patients with obesity compared to the control group (p &lt;0.001). There was no correlation between levels of magnesium biomarkers and the concentration of TBARS (p &gt;0.05). Conclusion: Patients with obesity showed a reduced dietary magnesium intake which seems to induce hypomagnesuria as a compensatory mechanism. The marker of oxidative stress evaluated in this study was not influenced by magnesium.

Effect of a maximal exercise test on serum and urinary concentrations of magnesium, phosphorous, rubidium and strontium in athletes

AimThis study aims to determine the changes induced by a maximal exercise test until exhaustion on the serum and urinary concentrations of Magnesium (Mg), Phosphorous (P), Rubidium (Rb) and Strontium (Sr) in athletes (AG) and sedentary students (SG). MethodsFifty subjects participated in the study divided into two groups. In AG there were twenty-five male athletes and in SG there were twenty-five male sedentary students. Both groups performed an exercise test until exhaustion, starting at 8 or 10 km/h respectively, and increasing the speed at 1 km/h every 400 m. Serum and urine samples were obtained from all participants before and after the test. ResultsRegarding the basal status, AG showed lower values of Mg in serum (p < 0.05) and urine (p < 0.01), but higher concentrations of serum P (p < 0.05) in comparison to SG. Comparing the pre and post-test values, corrected or non-corrected for hemoconcentration in serum and for creatinine in urine, AG showed a decrease in serum Mg (p < 0.05), in serum P (p < 0.01) and in urinary Sr (p < 0.01) while an increase was observed in urinary P (p < 0.05) and in urinary Rb (p < 0.05). ConclusionsIt can be concluded that a treadmill test until exhaustion leads to changes in serum and urinary concentrations of minerals in both AG and SG males. This may reflect an adaptive response of the body to overcome the physical stress and, in some cases, to avoid loss of these elements.

Effect of heat exposure and physical exercise until exhaustion in normothermic and hyperthermic conditions on serum, sweat and urinary concentrations of magnesium and phosphorus.

The aim of this survey was to ascertain the difference in the levels of Magnesium (Mg) and Phosphorus (P) after an exercise test in normothermia and hyperthermia before and after heat acclimation in comparison to their respective pre-test values. Twenty-nine male university students were divided into an Experimental Group (EG) (n = 15) and a Control Group (CG) (n = 14). All of them voluntarily participated in this investigation. Both groups performed an incremental test until exhaustion on a cycloergometer in normothermia (22 °C) and hyperthermia (42 °C). EG underwent 9 sessions of heat acclimation (100 °C) in a sauna (Harvia C105S Logix Combi Control; 3-15 W; Finland). Once the experimental period was completed, all initial measurements were carried out again under identical conditions. Urine and blood samples were obtained before and after each trial. Sweat samples were collected at the end of every test performed in hyperthermia. The samples were frozen at -80 °C until further analysis by ICP-MS. Lower seric Mg levels were observed in both groups at the end of pre-acclimation tests. After acclimation, only EG experimented a decrease of Mg in serum after testing (p < .01). The urinary excretion was unaffected in the pre-acclimated period, but EG experimented an increase in Mg after trials in the post-acclimation evaluation (p < .01). Mg sweat loss decreased significantly after heat acclimation (p < .05). P did not undergo changes, except in its urinary excretion, which was elevated after the normothermia trial in the post-acclimation period (p < .05). It seems that exercise in hyperthermia altered Mg status but not P homeostasis. Additionally, heat acclimation reduces Mg losses in sweat while increasing its loss in urine. Thus, Mg supplementation should be considered in unacclimated and acclimated subjects if physical exercise is going to be performed in hyperthermic conditions.

Influence of a physical exercise until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urinary concentrations of magnesium and phosphorus

AimThe aim of this study was to evaluate the effect of the performance of a maximal exercise test until exhaustion in normothermic and hyperthermic conditions on body concentrations of magnesium (Mg) and phosphorus (P). Methods19 adult males (age: 22.58 ± 1.05 years) performed two maximum incremental exercise tests on a cycloergometer separated by 48 h. The first was performed in normothermia (22 ± 2 °C) and the second in hyperthermic conditions induced with a sauna (42 ± 2 °C). Blood and urine samples were taken before and after each test. ResultsThe tests in hyperthermia did not produce ergospirometric alterations or a noticeable cardiovascular drift. Serum Mg concentrations underwent a reduction after the stress test in hyperthermia (p > 0.05) but not in normothermia. Nevertheless, urinary and erythrocyte concentrations of Mg, and urinary, erythrocyte and serum concentrations of P did not undergo alterations in either conditions. ConclusionsIt seems that exercise in hyperthermic conditions induces a tissue redistribution of Mg in the body, a fact which was not observed in normothermic conditions.

MP31-19 THE IMPACT OF TWENTY-FOUR HOUR URINE STUDY ON STENT EARLY ENCRUSTATION (SEE)

You have accessJournal of UrologyStone Disease: Medical & Dietary Therapy II1 Apr 2018MP31-19 THE IMPACT OF TWENTY-FOUR HOUR URINE STUDY ON STENT EARLY ENCRUSTATION (SEE) Daniel Rittenberg, William Berg, Yefim Sheynkin, Scott Herfel, and David Schulsinger Daniel RittenbergDaniel Rittenberg More articles by this author , William BergWilliam Berg More articles by this author , Yefim SheynkinYefim Sheynkin More articles by this author , Scott HerfelScott Herfel More articles by this author , and David SchulsingerDavid Schulsinger More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1048AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Stent Early Encrustation (SEE) presents a complicated technical challenge. We sought to examine and characterize differences in twenty-four hour urine (TFHU) studies between encrusters and non-encrusters. METHODS An IRB approved prospective study identified patients with SEE, defined as a calcified stent identified within 3 months of stent placement. From June 2016 to November 2017, patients with indwelling ureteral stents were evaluated for SEE upon exchange or removal and compared to patients without SEE. Demographic data and culture data were evaluated. TFHU studies were examined and compared between these two groups. RESULTS There were fifteen cases of SEE identified. The average age was 48 years old, with 53% being female. Thirteen patients screened were identified as non-encrusters, 42% of which were female, with an average age of 54 years. Non SEE patients were found to have statistically significant higher urinary concentrations of uric acid (0.729 vs 0.460 g/day, p = 0.05), sulfate (43.2 vs 20.0 mEq/day, p = 0.02), magnesium (115.1 vs 57.2 mg/day, p = 0.01), ammonium (44.6 vs 22.0 mmol/day, p = 0.02), and total creatinine (1954.9 vs 1157.2 mg/day, p = 0.03). Additionally, when compared to SEE, non SEE patients had a trend towards significance in total urine volume (2.253 vs 1.344 liters, p = 0.06) and urinary citrate (654.2 vs 374.8, p = 0.08. CONCLUSIONS Non SEE patients were found to have a significantly higher concentration of stone inhibitors. Additionally, urine volume and urinary citrate, were higher in the non SEE patients, although not statistically significant. Further investigation into concentrations of these stone inhibitors may lead to future development of ureteral stent composition to prevent SEE. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e419 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Daniel Rittenberg More articles by this author William Berg More articles by this author Yefim Sheynkin More articles by this author Scott Herfel More articles by this author David Schulsinger More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Magnesium supplementation: Pharmacokinetics in cardiac surgery patients with normal renal function

BackgroundIntravenous magnesium is routinely administered in intensive care units (ICU) to treat arrhythmias after cardiothoracic surgery. There are no data on the pharmacokinetics of continuous magnesium infusion therapy. ObjectiveTo investigate the pharmacokinetics of continuous magnesium infusion, focusing on serum and urinary magnesium concentration, volume of distribution and half-life. MethodsWe administered a 10 mmol bolus of magnesium-sulfate followed by a continuous infusion of 3 mmol/h for 12 h in twenty cardiac surgery patients. We obtained blood and urine samples prior to magnesium administration and after one, six, and 12 h. ResultsMedian magnesium levels increased from 1.09 (IQR 1.00–1.23) mmol/L to 1.59 (1.45–1.76) mmol/L after 60 min (p < .001), followed by 1.53 (1.48–1.71) and 1.59 (1.48–1.76) mmol/L after 6 and 12 h. Urinary magnesium concentration increased from 9.2 (5.0–13.9) mmol/L to 17 (13.6–21.6) mmol/L after 60 min (p < .001). Cumulative urinary magnesium excretion was 28 mmol (60.9% of the dose given). The volume of distribution was 0.25 (0.22–0.30) L/kg. There were no episodes of severe hypermagnesemia (≥3 mmol/L). ConclusionCombined bolus and continuous magnesium infusion therapy leads to a significant and stable increase in magnesium serum concentration despite increased renal excretion and redistribution.

Antilithiatic and Hepatoprotective Effects of Ferula assa-foetida Oleo-gum-resin on Ethylene Glycol-Induced Lithiasis in Rats

Objective: In this study, antiurolithiasic and hepatoprotective effects of Ferula assa-foetida oleo-gum-resin (asafoetida) were evaluated in Wistar rats. Methods: Negative control rats were provided with ethylene glycol (EG, 1%) in drinking water for 28 days. In treatment group, asafoetida was used simultaneously once daily for 28 days at the dose of 25 mg/kg. 8-h urine was collected from experimental animals at the end of the experiment. Urine level of creatinine, uric acid, urea, K+, Ca2+, Mg2+, Na+, phosphorus, and serum level of transaminase (alanine aminotransferase (ALT) and aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were evaluated. In addition, histopathological changes in kidney and liver were stained in hematoxylin and eosin. Results: Asafoetida showed a significant effect on urine volume; water intake and urinary ionic parameters were altered by EG, which elevated the calcium and inorganic phosphate; and asafoetida significantly reduced the elevated levels of these ions. In addition, asafoetida significantly elevated the urinary concentration of magnesium. ALT, AST, LDH, and ALP were elevated by EG and asafoetida significantly reduced the elevated levels of these parameters. The histological findings also showed improvement after treatment with the asafoetida. Conclusion: The presented data indicate that administration of asafoetida prevented the growth of urinary stones and also have hepatoprotective effect in experimental EG nephrolithiasis in Wistar rats.

Relationship between magnesium status and cardiovascular risk in obese women

Abstract Introduction The literature has shown reduced plasma concentrations of magnesium in obese individuals. It has been suggested that magnesium deficiency or changes in metabolism of this mineral participate in the pathophysiology of hypertension, arrhythmia and other cardiovascular diseases in obese patients. Objective This study evaluated the relationship between magnesium status and cardiovascular risk parameters in obese women. Methods Cross-sectional study involving 127 women, divided into two groups: obese (n = 63) and eutrophic (n = 64). The analysis of magnesium intake was carried out through the three-day food record and also Nutwin software. The plasma, erythrocyte and urinary magnesium concentrations were determined by flame atomic absorption spectrophotometry. Waist circumference was measured, and waist/height ratio and conicity index were calculated for assessment of cardiovascular risk. Results The mean value of magnesium intake was lower than those recommended. All the patients showed adequate mean concentrations of magnesium in plasma and erythrocytes. The urinary excretion of this mineral was lower than the reference values in both groups. Values of waist circumference, waist/height ratio and conicity index were higher in obese women (P Conclusion Obese patients intake foods with low dietary magnesium content, and they show hypomagnesuria as a compensatory mechanism to keep the plasma concentration of this mineral in adequate levels. The correlation analysis does not reveal the influence of magnesium on cardiovascular risk markers.

Pharmacokinetics of Magnesium Bolus Therapy in Cardiothoracic Surgery

To investigate the pharmacokinetics of a 20 mmol magnesium bolus in regards to serum and urinary magnesium concentration, volume of distribution, and half-life. Prospective, experimental study. A university-affiliated teaching hospital. Twenty consecutive cardiac surgery patients treated with magnesium bolus therapy for prevention of arrhythmia. A 20-mmol bolus of magnesium sulfate was administered intravenously. Median magnesium levels increased from 1.04 (interquartile range 0.94-1.23) mmol/L to 1.72 (1.57-2.14) mmol/L after 60 minutes of magnesium infusion (p < 0.001) but decreased to 1.27 (1.21-1.36) and 1.16 (1.11-1.21) mmol/L after 6 and 12 hours, respectively. Urinary magnesium concentration increased from 6.3 (4.2-14.5) mmol/L to 19.1 (7.4-34.5) mmol/L after 60 minutes (p < 0.001), followed by 22.7 (18.4-36.7) and 15 (8.4-19.7) mmol/L after 6 and 12 hours, respectively. Over the 12-hour observation period, the cumulative urinary magnesium excretion was 19.1 mmol (95.5% of the dose given). The median magnesium clearance was 10 (4.7-15.8) mL/min and increased to 14.9 (3.8-20.7; p = 0.934) mL/min at 60 minutes. The estimated volume of distribution was 0.31 (0.28-0.34) L/kg. Magnesium bolus therapy after cardiac surgery leads to a significant but short-lived increase of magnesium serum concentration due to renal excretion and distribution, and the magnesium balance is neutral after 12 hours.

Common variants in CLDN14 are associated with differential excretion of magnesium over calcium in urine.

The nature and importance of genetic factors regulating the differential handling of Ca2+ and Mg2+ by the renal tubule in the general population are poorly defined. We conducted a genome-wide meta-analysis of urinary magnesium-to-calcium ratio to identify associated common genetic variants. We included 9320 adults of European descent from four genetic isolates and three urban cohorts. Urinary magnesium and calcium concentrations were measured centrally in spot urine, and each study conducted linear regression analysis of urinary magnesium-to-calcium ratio on ~2.5 million single-nucleotide polymorphisms (SNPs) using an additive model. We investigated, in mouse, the renal expression profile of the top candidate gene and its variation upon changes in dietary magnesium. The genome-wide analysis evidenced a top locus (rs172639, p=1.7×10-12), encompassing CLDN14, the gene coding for claudin-14, that was genome-wide significant when using urinary magnesium-to-calcium ratio, but not either one taken separately. In mouse, claudin-14 is expressed in the distal nephron segments specifically handling magnesium, and its expression is regulated by chronic changes in dietary magnesium content. A genome-wide approach identified common variants in the CLDN14 gene exerting a robust influence on the differential excretion of Mg2+ over Ca2+ in urine. These data highlight the power of urinary electrolyte ratios to unravel genetic determinants of renal tubular function. Coupled with mouse experiments, these results support a major role for claudin-14, a gene associated with kidney stones, in the differential paracellular handling of divalent cations by the renal tubule.

ANTI-UROLITHIATIC POTENTIAL OF METHANOLIC EXTRACT OF HYGROPHILA SALICIFOLIA ON ETHYLENE GLYCOL INDUCED UROLITHIASIS IN RATSq

The anti-urolithiatic action of Hygrophila salicifolia (Acanthaceae) was determined by ethylene glycol induced lithiasis. Ethylene glycolated water (0.75% v/v) was given to experimental animals for 28 days to produce stone in kidney. Methanolic extracts of Hygrophila salicifolia were given from the 1st day as inhibitory agent. Urinary parameters such as calcium, oxalate and inorganic phosphate level were raised by ethylene glycol where as test extract lowered down the raised level of these ions in urine. Methanolic extract of Hygrophila salicifolia also increased urinary magnesium concentration while raised concentration of serum creatinine was found to be cut down during the experiment. Methanolic extract of test drug was found impressively better from histological study. These results obtained from the study confirmed the anti-urolithiatic potential of Hygrophila salicifolia.

The Contribution of Selected Urinary Solutes to the Determination of Urinary Osmolality in Guatemalan Preschool Children Consuming a Common Menu Offering

Background: Although water is the most abundant and most vital of all human nutrients, hydration is among the most ignored aspects of human nutrition. Many different solutes are eliminated by the kidneys in the urine flow, potentially contributing to the osmotic charge of this body fluid and acting as determinants of the urinary osmolality [Uosm]. Objectives: To measure urine osmolality concurrently with urea, uric acid, calcium, magnesium, potassium, sodium and inorganic phosphorus in a 24 h sample and to determine the patterns of their mutual interactions towards assessing the primary determinants of Uosm. Methods: Seventy-eight children from 2 to 7 years old, 40 girls and 38 boys, with median age of 57 mo underwent 24 h urine collections, with an aliquot separated for measuring urine osmolality by freezing-point-depression osmometry and solute concentrations by various analytical chemistry techniques. Spearman correlations and multiple regression models were run to assess interactions. Results: Backward-elimination multiple-regression models found that the urinary concentrations of inorganic phosphorus, urea, sodium, potassium and magnesium explained 95.1% of the variance in Uosm among the seven analytes quantified; calcium and uric acid made negligible contribution. Conclusion: The analyses allowed us to confirm the determinant roles of urea and the principal electrolytes, sodium and potassium, for urine osmolality and to appreciate coordination in the collateral collinear associations with other excreted solutes.