Renal calcium and magnesium handling during pregnancy: modeling and analysis.

Pregnancy is associated with elevated demand of most nutrients, with many trace elements and minerals critical for the development of fetus. In particular, calcium (Ca2+) and magnesium (Mg2+) are essential for cellular function, and their deficiency can lead to impaired fetal growth. A key contributor to the homeostasis of these ions is the kidney, which in a pregnant rat undergoes major changes in morphology, hemodynamics, and molecular structure. The goal of this study is to unravel the functional implications of these pregnancy-induced changes in renal handling of Ca2+ and Mg2+, two cations that are essential in a healthy pregnancy. To achieve that goal, we developed computational models of electrolyte and water transport along the nephrons of a rat in mid and late pregnancy. Model simulations reveal a substantial increase in the reabsorption of Mg2+ along the proximal tubules and thick ascending limbs. In contrast, the reabsorption of Ca2+ is increased in the proximal tubules but decreased in the thick ascending limbs, due to the lower transepithelial concentration gradient of Ca2+ along the latter. Despite the enhanced transport capacity, the marked increase in glomerular filtration rate results in elevated urinary excretions of Ca2+ and Mg2+ in pregnancy. Furthermore, we conducted simulations of hypocalcemia and hypomagnesemia. We found that hypocalcemia lowers Ca2+ excretion substantially more than Mg2+ excretion, with this effect being more pronounced in virgin rats than in pregnant ones. Conversely, hypomagnesemia reduces the excretion of Mg2+ and Ca2+ to more similar degrees. These differences can be explained by the greater sensitivity of the calcium-sensing receptor (CaSR) to Ca2+ compared with Mg2+.NEW & NOTEWORTHY A growing fetus' demands of minerals, notably calcium and magnesium, necessitate adaptations in pregnancy. In particular, the kidney undergoes major changes in morphology, hemodynamics, and molecular structure. This computational modeling study provides insights into how these pregnancy-induced renal adaptation impact calcium and magnesium transport along different nephron segments. Model simulations indicate that, despite the enhanced transport capacity, the marked increase in glomerular filtration rate results in elevated urinary excretions of calcium and magnesium in pregnancy.

24-Hour Urinary Chemistries and Kidney Stone Risk.

RATIONALE & OBJECTIVE: Most previous studies of the relationship between urinary factors and kidney stone risk have either assumed a linear effect of urinary parameters on kidney stone risk or implemented arbitrary thresholds suggesting biologically implausible "all-or-nothing" effects. In addition, little is known about the hierarchy of effects of urinary factors on kidney stone risk. This study evaluated the independent associations between urine chemistries and kidney stone formation and examined their magnitude and shape. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: We analyzed 9,045 24-hour urine collections from 6,217 participants of the Health Professionals Follow-Up Study and Nurses' Health Studies I and II. EXPOSURE: Urine volume and pH, and concentrations of calcium, citrate, oxalate, potassium, magnesium, uric acid, phosphorus, and sodium. OUTCOME: Incident symptomatic kidney stones. ANALYTICAL APPROACH: Multivariable logistic regression analysis incorporating restricted cubic splines to explore potentially nonlinear relationships between urinary factors and the risk of forming a kidney stone. Optimal inflection point analysis was implemented for each factor, and dominance analysis was performed to establish the relative importance of each urinary factor. RESULTS: Each urinary factor was significantly associated with stone formation except for urine pH. Higher urinary levels of calcium, oxalate, phosphorus, and sodium were associated with a higher risk of stone formation whereas higher urine volume, uric acid, citrate, potassium, and magnesium were associated with a lower risk. The relationships were substantially linear for urine calcium, uric acid, and sodium. By contrast, the magnitudes of the relationships were modestly attenuated at levels above the inflection points for urine oxalate, citrate, volume, phosphorus, potassium, and magnesium. Dominance analysis identified 3 categories of factors' relative importance: higher (calcium, volume, and citrate), intermediate (oxalate, potassium, and magnesium), and lower (uric acid, phosphorus, and sodium). LIMITATIONS: Predominantly White participants, lack of information on stone composition. CONCLUSIONS: Urine chemistries have complex relationships and differential relative associations with the risk of kidney stone formation. PLAIN-LANGUAGE SUMMARY: Kidney stones are common and likely to recur. Certain urinary factors play a role in the development of stones, but their independent roles, relative importance, and shapes of association with stone formation are not well-characterized. We analyzed 24-hour urine collections from individuals with and without kidney stones. Stones were less likely in those with higher urine volume, citrate, potassium, magnesium, and uric acid and were more likely in those with higher calcium, oxalate, phosphorus, and sodium. The acidity of the urine was not related to stones. The urinary parameters showed different degrees of relative importance, with calcium, volume, and citrate being greatest. All parameters exhibited a linear or close-to-linear shape of association with stone formation.

The relationship between hypomagnesemia and albuminuria in patients with type 2 diabetes mellitus.

OBJECTIVE: Diabetic nephropathy is a prevalent cause of chronic kidney disease worldwide. Magnesium plays a critical role in insulin resistance, and insulin, in turn, regulates magnesium levels. We aimed to investigate the association between hypomagnesemia and albuminuria in patients with type 2 diabetes mellitus (T2DM). DESIGN, PATIENTS AND MEASUREMENTS: This retrospective single-centre study encompassed 1178 patients aged 18 and above with T2DM, who attended our outpatient clinic between January 2019 and August 2020. Albuminuria levels were categorised according to Kidney Disease Outcomes Quality Initiative guidelines. In the literature, when examining cut-off values for hypomagnesemia, it is observed that studies typically use hospital normal level as a reference point. Hypomagnesemia, defined as magnesium levels below 1.6 mg/dL, was compared to normomagnesemia (magnesium between 1.6 and 2.4 mg/dL). The primary objective was to explore the impact of magnesium levels on albuminuria, while the secondary objective was to determine the prevalence of hypomagnesemia. The multivariate logistic regression analyses were performed according to age, gender (male), HbA1c, and presence of hypomagnesemia. RESULTS: The mean age of the participants was 58.7 ± 12.2 years, with 44% being male. Hypomagnesemia was identified in 5.3% of the patients. Advanced age and female gender were more common among patients with hypomagnesemia (p = .001). Magnesium levels exhibited a negative correlation with HbA1c and fasting blood glucose, and a positive correlation with creatinine levels (r = -.117, r = -.131, r = .117, p < .001 for all three variables). Hypomagnesemia was significantly more prevalent in patients with albuminuria (15.9% vs. 4.7%, p < .001). Moreover, participants with the presence of hypomagnesemia were independently associated with a higher risk of albuminuria (odds ratio 3,64 1.76-7.52, p = .001). CONCLUSION: Albuminuria is more frequently observed in patients with hypomagnesemia.

Dietary Magnesium Intake and Proteinuria: Is There a Relationship?

The possible relationship between dietary magnesium status and proteinuria has been suggested by a number of previous studies. However, human studies on this association are limited. Therefore, the present study aimed to investigate the independent relationship between dietary magnesium intake and urinary protein excretion. The present study was a post hoc analysis of the previous randomized clinical trial that evaluated the effect of dietary phosphorus restriction on proteinuria. The baseline data of 90 participants with proteinuria and chronic kidney disease was used to measure the association between dietary magnesium intake and proteinuria. Participants were asked to record their 24-h food intake for three days a week in a questionnaire. Urinary protein to creatinine ratio (UPCR) in a random urine sample was measured to be a marker for proteinuria. Out of 90 patients included in the study, 47 were men and 43 were women. The mean ± standard deviation of age and body mass index were 59.05 ± 14.16 years and 29.02 ± 5.54 kg/m2, respectively. The patients' average daily dietary intake of energy and magnesium were 2183 kcal and 169.44 mg, respectively. A significant inverse correlation was found between the dietary intake of magnesium and UPCR (r = - 0.219, p = 0.042). This association remained significant even after adjusting for confounding variables (ß = - 0.222, p = 0.028). The findings of the present study showed a significant inverse relationship between the magnesium intake and proteinuria. Although, the design of the current research was cross-sectional, it has provided a basis for conducting future longitudinal studies and trials to better elucidate such a relationship.

Magnesium Decreases Urine Supersaturation but Not Calcium Oxalate Stone Formation in Genetic Hypercalciuric Stone-Forming Rats.

BACKGROUND/AIMS: Hypercalciuria is the most common identifiable risk factor predisposing to CaOx stone formation. Increased oral magnesium intake may lead to decreased CaOx stone formation by binding intestinal Ox leading to decreased absorption and/or binding urinary Ox to decrease urinary supersaturation. This study assessed the effect of oral magnesium on 24-h urine ion excretion, supersaturation, and kidney stone formation in a genetic hypercalciuric stone-forming (GHS) rat model of human idiopathic hypercalciuria. METHODS: When fed the oxalate precursor, hydroxyproline, every GHS rat develops CaOx stones. The GHS rats, fed a normal calcium and phosphorus diet supplemented with hydroxyproline to induce CaOx, were divided into three groups of ten rats per group: control diet with 4.0 g/kg MgO, low MgO diet (0.5 g/kg), and high MgO diet (8 g/kg). At 6 weeks, 24-h urines were collected, and urine chemistry and supersaturation were determined. Stone formation was quantified. RESULTS: The GHS rats fed the low and high Mg diets had a significant reduction and increase, respectively, in urinary Mg compared to those fed the control diet. Dietary Mg did not alter urine Ca excretion while the low Mg diet led to a significant fall in urinary Ox. Urine supersaturation with respect to CaOx was significantly increased with low Mg, whereas urine supersaturation was significantly decreased with high Mg. There was no effect of dietary Mg on stone formation within 6 weeks of treatment. CONCLUSION: Dietary magnesium decreases urine supersaturation but not CaOx stone formation in GHS rats.

Effect of phyllanthus niruri on metabolic parameters of patients with kidney stone: a perspective for disease prevention

ABSTRACT Phyllanthus niruri (P.niruri) or stone breaker is a plant commonly used to reduce stone risk, however, clinical studies on this issue are lacking. Objective: To prospectively evaluate the effect of P. niruri on the urinary metabolic parameters of patients with urinary lithiasis. Materials and Methods: We studied 56 patients with kidney stones <10mm. Clinical, metabolic, and ultrasonography assessment was conducted before (baseline) the use of P. niruri infusion for 12-weeks (P. niruri) and after a 12-week (wash out) Statistical analysis included ANOVA for repeated measures and Tukey's/McNemar's test for categorical variables. Significance was set at 5%. Results: Mean age was 44±9.2 and BMI was 27.2±4.4kg/m2. Thirty-six patients (64%) were women. There were no significant changes in all periods for anthropometric and several serum measurements, including total blood count, creatinine, uric acid, sodium, potassium, calcium, urine volume and pH; a significant increase in urinary potassium from 50.5±20.4 to 56.2±21.8 mg/24-hour (p=0.017); magnesium/creatinine ratio 58±22.5 to 69.1±28.6mg/gCr24-hour (p=0.013) and potassium/creatinine ratio 39.3±15.1 to 51.3±34.7mg/gCr24-hour (p=0.008) from baseline to wash out. The kidney stones decreased from 3.2±2 to 2.0±2per patient (p<0.001). In hyperoxaluria patients, urinary oxalate reduced from 59.0±11.7 to 28.8±16.0mg/24-hour (p=0.0002), and in hyperuricosuria there was a decrease in urinary uric acid from 0.77±0.22 to 0.54±0.07mg/24-hour (p=0.0057). Conclusions: P.niruri intake is safe and does not cause significant adverse effects on serum metabolic parameters. It increases urinary excretion of magnesium and potassium caused a significant decrease in urinary oxalate and uric acid in patients with hyperoxaluria and hyperuricosuria. The consumption of P.niruri contributed to the elimination of urinary calculi.

Perfil de riesgo litogénico en pacientes con urolitiasis en Paraguay / Lithogenic risk in patients from Paraguay with urolithiasis

The lithogenic risk profile is a graphical representation of metabolic factors and urinary saturation involved in the stone formation with their respective critical values. Aim: To determine the lithogenic risk profile in patients with urolithiasis. Material and Methods: Personal data such as anthropometric, history of diseases and family history of urolithiasis were recorded. Different compounds acting as promoters or inhibitors of crystallization were measured in serum and urine samples, and the data obtained were used to calculate urinary saturation using Equil software. Results: We included 30 men and 43 women with a median age of 45 (34-54) years. Overweight and family history of urolithiasis was reported in 63 and 32% respectively. Crystallization risk was detected in 74% of participants. The most common urinary abnormalities were hypocitraturia in 48% and hypercalciuria in 40%. Conclusions: The lithogenic profile revealed urinary saturation compatible with crystallization risk in 74% of the studied patients.

Are patients with lichen planus really prone to urolithiasis? Lichen planus and urolithiasis

ABSTRACT Purpose to investigate whether patients with lichen planus (LP) are really prone to urolithiasis or not. Patients and Methods We performed a prospective analysis of 40 patients diagnosed with lichen planus (LP) (group I), and 40 volunteers did not have LP before (group II). Participants were all checked for urolithiasis by radiological investigations. Blood samples were analyzed for biochemistry parameters including calcium and uric acid. 24-h urine samples were analyzed to investigate oxalate, citrate calcium, uric acid, magnesium, sodium and creatinine. Results Men/women ratio and mean age were similar between group I and II (p>0.05). A presence or history of urolithiasis was detected in 8 (20%) and 2 (%5) patients in group I and II, respectively (p<0.05). Hypocitraturia was the most common anomaly with 35% (n:14) in group I. The rate of hypocitraturia in group II was 12.5% (n:5) and the difference was statistically significantly different (p=0.036). In group I, hyperuricosuria and hyperoxaluria followed with rates of 27.5% (n:11) and 25% (n:10), respectively. The rate of hyperuricosuria and hyperoxaluria were both 5% (n:2) in group II and the differences were significant (p<0.05). Hyperuricemia was another important finding in the patients with LP. It was detected in 13 (32.5%) patients in group I and in 1 (2.5%) participant in group II (p=0.001). Conclusion According to our results, metabolic disorders of urolithiasis were highly detected in the patients with LP. However, similar to the etiology of LP, the exact reasons for these metabolic abnormalities in LP remain a mystery.

Influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes / Influencia de magnesio en la bioquímica del hierro y el estrés oxidativo en pacientes con diabetes tipo 2

Introduction: Studies have shown that oxidative stress, found in patients with type 2 diabetes, may be due to changes in the metabolism of minerals, such as magnesium and iron. Data related to compartmentalization of these minerals in diabetes are scarce and controversial. Objective: This study assessed the influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes. Methods: A case-control study in male and female subjects aged 27-59 years, divided into two groups: type 2 diabetes (n=40) and control (n=48). Intake of magnesium and iron was assessed by three-day food record. Plasma, erythrocyte and urinary levels of magnesium, serum iron, ferritin, total iron binding capacity, fasting glucose, glycated hemoglobin, insulin, creatinine clearance and plasma thiobarbituric acid reactive substances (TBARS) were analyzed. Results and Discussion: Magnesium intake and plasma magnesium were lower in diabetic subjects. There was low urinary magnesium excretion, with no difference between groups. Although normal, the diabetic group had lower serum iron and ferritin concentrations compared to control subjects. Plasma TBARS in diabetic patients was higher than control while creatinine clearance was lower. An inverse correlation between erythrocyte magnesium and serum iron and ferritin was observed in the diabetes group. Conclusions: Diabetes induced hypomagnesemia and this, associated with chronic hyperglycemia, may have enhanced oxidative stress. Erythrocyte magnesium may have contributed to prevent iron overload and worsening of oxidative stress and hyperglycemic status (AU)

Introducción: Los estudios han demostrado que el estrés oxidativo, que se encuentra en pacientes con diabetes tipo 2, puede ser debido a cambios en el metabolismo de los minerales, como el magnesio y el hierro. Los datos relacionados con la compartimentación de estos minerales en la diabetes son pocos y cuestionables. Objetivos: Evaluar la influencia del magnesio sobre parámetros bioquímicos de hierro y el estrés oxidativo en pacientes con diabetes tipo 2. Métodos: Estudio caso-control en los sujetos masculinos y femeninos de edad 27 a 59 años, divididos en dos grupos: la diabetes tipo 2 (n = 40) y control (n = 48). La ingesta de magnesio y hierro se evaluó por tres días registro de alimentos. Plasma, eritrocitos y los niveles urinarios de magnesio, hierro sérico, ferritina, capacidad total de fijación del hierro, glucosa en ayunas, hemoglobina glucosilada, la insulina, el aclaramiento de creatinina y el plasma se analizaron tiobarbitúrico sustancias reactivas al ácido (TBARS). Resultados y Discusión: La ingesta de magnesio y el magnesio en plasma fueron más bajos en los pacientes diabéticos. Hubo baja excreción urinaria de magnesio, sin diferencias entre los grupos. Aunque lo normal, el grupo de diabéticos tenían concentraciones de hierro y ferritina sérica inferiores en comparación con los sujetos control. TBARS plasmáticos en los pacientes diabéticos fue mayor que en el control, mientras que la depuración de creatinina fue menor. Se observó una correlación inversa entre el magnesio y el hierro en suero de los eritrocitos y la ferritina en el grupo de diabetes Conclusiones: Diabetes hipomagnesemia inducida y esto, asociado a la hiperglucemia crónica, pueden haber mejorado el estrés oxidativo. Magnesio eritrocitaria puede haber contribuido a evitar la sobrecarga de hierro y el empeoramiento de estrés oxidativo y el estado de hiperglucemia (AU)

Use of the probability of stone formation (PSF) score to assess stone forming risk and treatment response in a cohort of Brazilian stone formers

Introduction The aim was to confirm that PSF (probability of stone formation) changed appropriately following medical therapy on recurrent stone formers. Materials and Methods Data were collected on 26 Brazilian stone-formers. A baseline 24-hour urine collection was performed prior to treatment. Details of the medical treatment initiated for stone-disease were recorded. A PSF calculation was performed on the 24 hour urine sample using the 7 urinary parameters required: voided volume, oxalate, calcium, urate, pH, citrate and magnesium. A repeat 24-hour urine sample was performed for PSF calculation after treatment. Comparison was made between the PSF scores before and during treatment. Results At baseline, 20 of the 26 patients (77%) had a high PSF score (> 0.5). Of the 26 patients, 17 (65%) showed an overall reduction in their PSF profiles with a medical treatment regimen. Eleven patients (42%) changed from a high risk (PSF > 0.5) to a low risk (PSF < 0.5) and 6 patients reduced their risk score but did not change risk category. Six (23%) patients remained in a high risk category (> 0.5) during both assessments. Conclusions The PSF score reduced following medical treatment in the majority of patients in this cohort. .

Estudio comparativo de la excreción urinaria de boro, calcio, magnesio y fósforo en mujeres posmenopáusicas con y sin osteoporosis / Comparative study of the urinary excretion of boron, calcium, magnesium and phosphorus in postmenopausal women with and without osteoporosis

Con el propósito de comparar la posible relación entre las concentraciones urinarias de boro y las concentraciones de calcio, de magnesio y de fósforo en suero y orina de mujeres posmenopáusicas con y sin osteoporosis, seleccionamos 45 mujeres posmenopáusicas con más de 47 años de edad, divididas en dos subgrupos: grupo I mujeres posmenopáusicas clínicamente sanas y grupo II mujeres posmenopáusicas con osteoporosis, sin enfermedades renales, hepáticas o diabetes mellitus. Se determinó el boro (B), el fósforo (P), el calcio total (Ca) y el magnesio total (Mg) en la orina de dos horas por espectroscopia de emisión atómica con plasma acoplado por inducción (ICPA-ES), el calcio y el magnesio total en suero por espectroscopia de absorción atómica en llama (FAAS) y el fósforo inorgánico en suero y la creatinina en suero y orina por espectroscopia de absorción molecular. Los resultados obtenidos sugieren preliminarmente una diferencia significativa (p<0,05) en las concentraciones de boro y de fósforo en la orina de dos horas entre los grupos estudiados. El análisis de regresión lineal aplicado, sugiere relación entre el índice boro/creatinina y los índices calcio/creatinina, magnesio/creatinina y fósforo/creatinina en la orina de las mujeres posmenopáusicas con osteoporosis.

In order to compare the possible relationship between urinary concentrations of boron, calcium, magnesium and phosphorus in serum and urine of postmenopausal women with and without osteoporosis, we selected 45 postmenopausal women over 47 years of age, divided into two groups: group I clinically healthy postmenopausal women and group II postmenopausal women with osteoporosis, without chronic kidney and hepatic diseases or diabetes mellitus. We determined the boron (B), phosphorus (P), total calcium (Ca) and total magnesium (Mg) in the urine of two hours, by atomic emission spectroscopy with induction-coupled plasma (ICPA-ES). Total calcium and total magnesium in serum were determined by atomic flame absorption spectroscopy (FAAS) and inorganic phosphorus in serum, and creatinine in serum and urine, by molecular absorption spectrometry. The preliminary results suggest the existence of a significant difference (p <0.05) in boron and phosphorus concentrations in the urine of two hours between the groups. The model of linear regression analysis used showed a relationship between urinary concentrations of boron/creatinine index and calcium/ creatinine, magnesium/creatinine and phosphorus/creatinine indexes in the urine of postmenopausal women with osteoporosis.

Urinary lithiasis and idiopathic hypercalciuria: the importance of dietary intake evaluation

PUSPOSE: To evaluate food intake of patients with urinary lithiasis and idiopathic hypercalciuria (IH). MATERIALS AND METHODS: Between August 2007 and June 2008, 105 patients with lithiasis were distributed into 2 groups: Group 1 (n = 55) - patients with IH (urinary calcium excretion > 250 mg in women and 300 mg in men with normal serum calcium); Group 2 (n = 50) - normocalciuria (NC) patients . Inclusion criteria were: age over 18, normal renal function (creatinine clearance = 60 mL/min), absent proteinuria and negative urinary culture. Pregnant women, patients with some intestinal pathology, chronic diarrhea or using corticoids were excluded. The protocol of metabolic investigation was based on non-consecutive collection of two 24-hour samples for dosages of: calcium, sodium, uric acid, citrate, oxalate, magnesium and urinary volume. Food intake was evaluated through the quantitative method of Dietary Register of three days. RESULTS: Urinary excretion of calcium (433.33 ± 141.92 vs. 188.93 ± 53.09), sodium (280.08 ± 100.94 vs. 200.44.93 ± 65.81), uric acid (880.63 ± 281.50 vs. 646.74 ± 182.76) and magnesium (88.78 ± 37.53 vs. 64.34 ± 31.84) was significantly higher in the IH group in comparison to the NC group (p < 0.05). As regards the nutritional composition of food intake of IH and NC groups, there was no statistical significant difference in any nutrient evaluated. CONCLUSION: In our study, no difference was observed in the food intake of patients with urinary lithiasis and IH or NC.

Corpus of biochemical changes after death by potassium intoxication in rabbits / 法医学杂志

OBJECTIVE@#To explore the objective evidence of the corpus biochemical changes in rabbits for postmortem diagnosis of potassium intoxication.@*METHODS@#Rabbits were sacrificed by Infusion of 0.3% KCl at full speed push or 1% KCl at 100 drip/min, respectively, with normal rabbits used as control. Cardiac blood and urine samples were collected before and after potassium infusion to examine the concentrations of various electrolytes (K+, Na+, Ca2+, Mg2+, Cl-, and HCO3-) and to observe the antemortem and postmortem biochemical changes.@*RESULTS@#The mean lethal infusion time in the 0.3%KCl group was longer than that in the 1% KCl group (P = 0.006). The serum concentration of K+ increased while the serum concentrations of Na+, Ca2+, Cl-, and HCO3- decreased after the infusion. There were no statistically significant differences in the whole blood concentration of K+ as well as the serum concentration of Mg2+ between the two groups (P = 0.062). There were statistically significant differences in the concentrations of whole blood K+, as well as serum Na+, Mg2+, and Cl-, but not in the serum K+, Ca2+, and HCO3-. There were no statistically significant differences seen in the urine volumes and the concentrations of all the urine electrolytes between the groups.@*CONCLUSION@#Examination of the concentrations of K+ both in the whole blood and serum, as well as Mg2+ in the serum may be helpful for postmortem diagnosis of potassium intoxication.

Deficiência de magnésio e resistência à insulina em pacientes com diabetes mellitus tipo 2 / Magnesium deficiency and insulin resistance in patients with type 2 diabetes mellitus

O magnésio é um íon predominantemente intra-celular, que participa como co-fator de mais de 300 reações enzimáticas, dentre elas na atividade da tirosino-cinase. Sua deficiência pode aumentar a resistência periférica à insulina, especialmente em pacientes com síndrome metabólica e diabetes mellitus tipo 2 (DM2). Este trabalho avaliou, em 27 pacientes com DM2 descompensado, o conteúdo intra-celular de magnésio, correlacionando-o com índices laboratoriais de resistência insulínica e controle glicêmico. Hipomagnesemia foi encontrada em 75 por cento dos pacientes e déficit intra-celular em 30,8 por cento. Houve correlação negativa do Mg intra-celular (Mg IC) com HbA1 e com IMC. 59,2 por cento dos pacientes apresentaram HOMA IR > 3,5, e tendência para correlação negativa com o Mg IC, porém sem significância estatística. Apesar do número pequeno de pacientes, ressalta-se que uma vez que deficiência de magnésio é comum em pacientes com diabetes, sua relação com resistência insulínica deve ser mais estudada.

The relationship of magnesium intake to serum and urinary calcium and magnesium levels in Trinidadian stone formers

BACKGROUND:  The present study was undertaken to investigate the relationship between the dietary intake of magnesium and the serum and urinary levels of calcium and magnesium in a group of Trinidadian stone formers. METHODS:  A group of 102 confirmed stone formers presenting to urological clinics were interviewed using a questionnaire designed to obtain a semi-quantitative estimate of their oral magnesium intake. Patients were invited to give blood samples for serum calcium and magnesium levels and to provide 24-h urine specimens for the measurement of urinary levels of these minerals, as well as total urinary volumes. A group of 102 controls was subjected to a similar interview and blood and urinary testing. Chi-square tests and Student's t-tests were used to examine group demographic differences. The Mann–Whitney test investigated differences in biochemical indices. Binary logistic regression was used to identify predictors of stone formation. RESULTS:  Blood samples were obtained from 60 patients and 98 controls. Urine samples were returned by 34 patients and 97 controls. Only 10 stones were retrieved from patients. Patients had a significantly lower magnesium intake, but higher median serum and urinary calcium levels, and higher serum calcium to magnesium ratios than controls. Independent variables capable of predicting stone formation included total magnesium intake and serum and urinary calcium levels. CONCLUSIONS:  Increased serum and urinary calcium levels, calcium to magnesium ratios, and a low magnesium intake were predictive of stone formation in this Trinidadian population.

Valores de referência de parâmetros urinários envolvidos na litogênese / Reference values of urinary parameters that participate in lithogenesis

Neste trabalho determinamos em nossa populaçao, os valores normais de parâmetros urinários que participam na formaçao de cálculos renais, bem como de creatinina comparando-os com os relatados na literatura. Os valores em média + desvio padrao (X+DP) do grupo controle (N=200) e do grupo formador de cálculos (N=200) sao respectivamente: citrato (525 + 160 vs 263 + 90 mg/24h, p<0,05), cálcio (149 + 50 vs 223 + 80 mg/24h, p<0,05), ácido úrico (556 + 130 vs 620 + 160 mg/24h, p<0,05), sódio (192 + 60 vs 208 + 60 mEq/24h, p<0,05), potássio (37 + 10 vs 43 + 10 mEq/24h, p<0,05), magnésio (81 + 17 vs 67 + 25 mg/24h, p<0,05) e creatinina (1409 + 340 vs 1436 + 320 mg/24h, p<0,05). Os valores para o citrato, cálcio, ácido úrico, sódio e creatinina para as mulheres-controles neste trabalho foram similares, enquanto que os valores para o potássio foram maiores e para o magnésio foram menores que os valores descritos na literatura. Os homens-controle apresentaram todos os parâmetros mais elevados, exceto para o citrato e potássio que foram menores que os da literatura. Comparando estes resultados com os valores da literatura internacional, observamos diferenças significantes, realçando a necessidade em normalizar os valores de referência para distintas populaçoes de formadores de cálculos renais.

Magnesium balance studies in marasmic kwashiorkor

Studies of magnesium balance were made on 3 Jamaican infants during recovery from marasmic kwashiorkor. Analysis of muscle biopsy specimens indicated a marked deficit of magnesium as well as potassium in all cases. The serum magnesium level was slightly low in one case. A positive magnesium balance was maintained for several weeks in recovery and was accompanied by low urinary excretion. In one case there was considerable intestinal absorption of magnesium, even in the presence of diarrhea. Efficient absorption of a high oral suppliment tended to overcome renal conservation. Previous analysis has suggested that the deficiency of intracellular electrolytes in wet muscle samples is due partly to the reduced intracellular volume associated with protein loss and partly to a true electrolyte deficit. The positive magnesium balance in recovery is therefore attributable both to intracellular repletion and to tissue growth; the latter tends to be masked clinically by loss of excess body water. Little is known of the additional factor of the repletion of magnesium in bone, but the evidence from animal experiments is that the deficit in bone may be very substantial (AU)

Saturación urinaria con oxalato de calcio en urolitiasis / Urine saturation with calcium oxalate in urolithiasis

Mediante un programa de computación iterativo se calculó el Producto de Actividad (PA) del oxalato de calcio (OxCa) con datos de orina de 24 h de 30 pacientes litiásicos formadores de cálculos de OxCa y 30 controles sanos. Los resultados muestran una diferencia estadísticamente significativa entre los valores medios de ambos grupos, tanto en el PA como en la concentración urinaria de calcio, magnesio, citrato y oxalato. La mayor contribución relativa del oxalato y el citrato en el aumento y descenso, respectivamente, del PA es puesta de manifiesto. Se confirma la utilidad del cálculo del PA para establecer el riesgo aumentado de formar cálculos y el seguimiento del tratamiento instaurado (AU)

Saturación urinaria con oxalato de calcio en urolitiasis / Urine saturation with calcium oxalate in urolithiasis

Mediante un programa de computación iterativo se calculó el Producto de Actividad (PA) del oxalato de calcio (OxCa) con datos de orina de 24 h de 30 pacientes litiásicos formadores de cálculos de OxCa y 30 controles sanos. Los resultados muestran una diferencia estadísticamente significativa entre los valores medios de ambos grupos, tanto en el PA como en la concentración urinaria de calcio, magnesio, citrato y oxalato. La mayor contribución relativa del oxalato y el citrato en el aumento y descenso, respectivamente, del PA es puesta de manifiesto. Se confirma la utilidad del cálculo del PA para establecer el riesgo aumentado de formar cálculos y el seguimiento del tratamiento instaurado

Hipomagnesiúria e litíase renal / Hypomagnesemia and renal lithiasis

Dentre os 309 pacientes avaliados no Ambulatório de Litíase Renal do Hupe, segundo o protocolo de Pak, de 1987 a 1989, 91 foram selecionados aleatoriamente e submetidos a dosagem de magnésio urinário. Em 68 (74,7 por cento) casos encontramos magnesiúria normal. Em 23 casos (25,2 por cento) encontramos hipomagnesiúria (< 4mEq/24h), sendo que em dois (2,1 por cento) havia associaçao com hipercalciúria, em nove (9,8 por cento) associaçao com hiperuricosúria e em quatro (4,3 por cento) associaçao com hipercalciúria e hiperuricosúria. Em oito pacientes (8,7 por cento) a hipomagnesiúria foi achado único. Estes dados salientam a importância de se avaliar a magnesiúria em portadores de cálculo renal.