Antacid-induced hypermagnesemia in a patient with normal renal function and bowel obstruction

An inhibitory mechanism for suppressing high salt intake in Drosophila

High concentrations of dietary salt are harmful to health. Like most animals, Drosophila melanogaster are attracted to foods that have low concentrations of salt, but show strong taste avoidance of high salt foods. Salt in known on multiple classes of taste neurons, activating Gr64f sweet-sensing neurons that drive food acceptance and 2 others (Gr66a bitter and Ppk23 high salt) that drive food rejection. Here we find that NaCl elicits a bimodal dose-dependent response in Gr64f taste neurons, which show high activity with low salt and depressed activity with high salt. High salt also inhibits the sugar response of Gr64f neurons, and this action is independent of the neuron's taste response to salt. Consistent with the electrophysiological analysis, feeding suppression in the presence of salt correlates with inhibition of Gr64f neuron activity, and remains if high salt taste neurons are genetically silenced. Other salts such as Na2SO4, KCl, MgSO4, CaCl2, and FeCl3 act on sugar response and feeding behavior in the same way. A comparison of the effects of various salts suggests that inhibition is dictated by the cationic moiety rather than the anionic component of the salt. Notably, high salt-dependent inhibition is not observed in Gr66a neurons-response to a canonical bitter tastant, denatonium, is not altered by high salt. Overall, this study characterizes a mechanism in appetitive Gr64f neurons that can deter ingestion of potentially harmful salts.

Clinical features of hypermagnesemia in patients with functional constipation taking daily magnesium oxide

Although magnesium oxide is widely used as a laxative, alterations in serum magnesium concentrations among patients taking daily magnesium oxide have not been clarified. The present retrospective, cross-sectional study investigated the risk factors for hypermagnesemia in patients taking daily oral magnesium oxide. Of 2,176 patients administered daily magnesium oxide, 193 (8.9%) underwent assays of serum magnesium concentrations and were evaluated. High serum magnesium concentration and hypermagnesemia were defined as serum magnesium concentrations ≥2.5 mg/dl and ≥3.0 mg/dl, respectively. Of the 193 patients taking daily magnesium oxide, 32 (16.6%) had high serum magnesium concentration and 10 (5.2%) had hypermagnesemia. Factors associated with hypermagnesemia included chronic kidney disease (CKD) grade 4 (p = 0.014) and magnesium oxide dosage (p = 0.009). Factors associated with high serum magnesium concentration included magnesium oxide dosage >1,000 mg/day (p = 0.004), CKD grades 4 (p = 0.000) and concomitant use of stimulant laxatives (p = 0.035). Age, however, was not associated with hypermagnesemia or high serum magnesium concentration. In conclusion, renal function and magnesium oxide dosage, but not age, were associated with hypermagnesemia and high serum magnesium concentration in patients with functional constipation taking daily magnesium oxide.

The characteristics of patients with hypermagnesemia who underwent emergency hemodialysis

Aim

This study aimed to clarify the characteristics of patients who presented with severe hypermagnesemia and subsequently underwent emergency hemodialysis.

Methods

We investigated the age, gender, complications, clinical symptoms, causal drugs, electrocardiogram findings, and laboratory data of 15 patients.

Results

Magnesium oxide had been administered in all cases and 14 patients were over 65 years old. The male : female ratio was 6:9. Chief complaints included a disturbance of consciousness, hypotension, bradycardia, and respiratory failure. The median serum magnesium value before hemodialysis was 6.0 (3.7–18.6) mg/dL. The daily dosage of magnesium oxide was ≤ 2.0 g in 12 cases. The median serum creatinine value before hemodialysis was 5.39 (0.54–10.29) mg/dL. However, in two cases, the creatinine value was not elevated. Complications of acute kidney injury exacerbated the hypermagnesemia in nine cases.

Conclusions

We recommend that the serum magnesium value should be measured in older patients who are taking magnesium oxide and are showing signs and symptoms of a disturbance of consciousness, hypotension, bradycardia, and respiratory failure of an uncertain etiology, even if the serum creatinine value is not elevated or the dosage of magnesium oxide is within recommended levels.

Fatal Hypermagnesemia Due to Laxative Use

We report a case of fatal hypermagnesemia in a 53-year-old woman admitted for acute exacerbation of chronic obstructive pulmonary disease and with a history of chronic constipation treated regularly with magnesium-containing laxatives. On admission, her magnesium level was 2.0mg/dL, which rose to a peak of 10.8mg/dL despite hydration and diuresis in the presence of a normal kidney function. Continuous renal replacement therapy was promptly initiated, which reduced her serum magnesium levels, but her condition continued to deteriorate precipitously progressing to shock leading to oligoanuric renal failure, and she died 2 days later. A review of the literature shows that though rare and often unsuspected, severe hypermagnesemia frequently results in death even in individuals with normal renal function despite renal replacement therapy. In patients with constipation, retention of magnesium-based laxative in the gut apparently serves as a reservoir for continuous magnesium absorption and contributes to mortality.

Magnesium basics

As a cofactor in numerous enzymatic reactions, magnesium fulfils various intracellular physiological functions. Thus, imbalance in magnesium status-primarily hypomagnesaemia as it is seen more often than hypermagnesaemia-might result in unwanted neuromuscular, cardiac or nervous disorders. Measuring total serum magnesium is a feasible and affordable way to monitor changes in magnesium status, although it does not necessarily reflect total body magnesium content. The following review focuses on the natural occurrence of magnesium and its physiological function. The absorption and excretion of magnesium as well as hypo- and hypermagnesaemia will be addressed.

Dietary magnesium intake is inversely associated with serum C-reactive protein levels: meta-analysis and systematic review

BACKGROUND/OBJECTIVES

The aim of this study was to quantitatively summarize the association of dietary magnesium (Mg) intake with serum C-reactive protein (CRP) levels in the general population.

SUBJECTS/METHODS

Observational and experimental studies through February 2013 were reviewed in PubMed and EMBASE. Additional information was retrieved through Google or hand search of related reference lists. The main outcome is either adjusted geometric mean of CRP or odds ratio (OR) of having serum CRP ≥ 3 mg/l. Meta-regression was used to determine the linear association of dietary Mg intake and adjusted geometric means of CRP levels. A fixed-effects model was used to pool ORs of interest, comparing those in the lowest with those in the highest group of dietary Mg intake.

RESULTS

A data set derived from seven cross-sectional studies including 32,918 participants was quantitatively assessed. A weighted inverse association between Mg intake and serum CRP levels was observed (β-coefficient: -0.0028; 95% confidence interval (CI), -0.0043 to -0.0013; P(trend) = 0.001) from four cross-sectional studies. The pooled OR (95% CI) of having CRP ≥ 3 mg/l was 1.49 (1.18-1.89) on comparing the lowest to the highest group of Mg intake from three studies with the data available. Qualitative assessment among five intervention studies also showed a potential beneficial effect of Mg intake on serum CRP levels.

CONCLUSIONS

This meta-analysis and systematic review indicates that dietary Mg intake is significantly and inversely associated with serum CRP levels. The potential beneficial effect of Mg intake on chronic diseases may be, at least in part, explained by inhibiting inflammation.

Fatal hypermagnesemia induced by preoperative colon preparation in an elderly woman: report of a case

An 85-year-old woman with rectal carcinoma was referred to our hospital for surgical treatment. She had a history of constipation treated with oral magnesium oxide. She received 34 g of magnesium citrate (Magcolol P(®)) orally for 2 days as a mechanical bowel preparation prior to the operation. Just before the operation, she suddenly developed nausea, vomiting, and cyanosis and went into cardiac arrest. Despite support by mechanical ventilation, dopamine, dobutamine, and norepinephrine, she exhibited repeated bradycardia that was nearly fatal and required temporary pacing. The following day, her laboratory tests revealed marked hypermagnesemia (14.3 mg/dL). After a hemodialysis session, she recovered dramatically and all vasopressors were withdrawn. We conclude that preoperative mechanical bowel preparation with magnesium-containing cathartics can cause fatal hypermagnesemia in elderly patients even if their renal function is normal.

Drug-induced alterations in Mg2+ homoeostasis

Magnesium (Mg2+) balance is tightly regulated by the concerted actions of the intestine, bone and kidneys. This balance can be disturbed by a broad variety of drugs. Diuretics, modulators of the EGFR (epidermal growth factor receptor), proton pump inhibitors, antimicrobials, calcineurin inhibitors and cytostatics may all cause hypomagnesaemia, potentially leading to tetany, seizures and cardiac arrhythmias. Conversely, high doses of Mg2+ salts, frequently administered as an antacid or a laxative, may lead to hypermagnesaemia causing various cardiovascular and neuromuscular abnormalities. A better understanding of the molecular mechanisms underlying the adverse effects of these medications on Mg2+ balance will indicate ways of prevention and treatment of these adverse effects and could potentially provide more insight into Mg2+ homoeostasis.

Magnesium sulfate for acute asthma in adults: a systematic literature review

Magnesium sulfate (MgSO(4)) has been considered as an adjunct therapy for severe and life-threatening asthma exacerbation. The literature search was performed using MEDLINE, EMBASE, Cochrane Library and Google Scholar to summarize the current state of knowledge regarding magnesium therapy in acute exacerbation of adult asthma. A total of 16 trials and 4 meta-analyses were identified. As results, intravenous MgSO(4) was beneficial in severe exacerbation, but evidence for nebulized magnesium was insufficient. However, larger trials are required to draw confirmative conclusions on the efficacy. Regarding the safety concern, the risk of major toxicity appears to be very low at usual doses described in the literature. Additionally, results from 4 surveys were examined on the gaps between knowledge and practice, and on the barrier to the use of MgSO(4) at emergency departments. This literature review summarized the up-to-date evidence on the issues regarding the use of MgSO(4) for acute asthma. We expect more studies to be conducted for evidence making in the Asian-Pacific regions.

Paralytic ileus requiring hospitalization secondary to high-dose antipsychotic polypharmacy and benztropine

Ileus can result from the combined activity of antipsychotic and anticholinergic medications. Despite frequent use, case reports in the literature are sparse. We present a patient who developed a paralytic ileus requiring extended hospitalization. Providers should minimize antipsychotic and concurrent anticholinergic medications, consider prophylactic bowel regimens and monitor for constipation.

Serum magnesium concentration in children with functional constipation treated with magnesium oxide

AIM: To determine whether hypermagnesemia recently reported in adult patients possibly develops in children with functional constipation taking daily magnesium oxide.

METHODS: We enrolled 120 patients (57 male and 63 female) aged 1-14 years old (median: 4.7 years) with functional constipation from 13 hospitals and two private clinics. All patients fulfilled the Rome III criteria for functional constipation and were treated with daily oral magnesium oxide for at least 1 mo. The median treatment dose was 600 (500-800) mg/d. Patients were assessed by an interview and laboratory examination to determine possible hypermagnesemia. Serum magnesium concentration was also measured in sex- and age-matched control subjects (n = 38).

RESULTS: In the constipation group, serum magnesium concentration [2.4 (2.3-2.5) mg/dL, median and interquartile range] was significantly greater than that of the control group [2.2 (2.0-2.2) mg/dL] (P < 0.001). The highest value was 3.2 mg/dL. Renal magnesium clearance was significantly increased in the constipation group. Serum magnesium concentration in the constipation group decreased significantly with age (P < 0.01). There was no significant correlation between the serum level of magnesium and the duration of treatment with magnesium oxide or the daily dose. None of the patients had side effects associated with hypermagnesemia.

CONCLUSION: Serum magnesium concentration increased significantly, but not critically, after daily treatment with magnesium oxide in constipated children with normal renal function.

Hypermagnesemia predicts mortality in elderly with congestive heart disease: relationship with laxative and antacid use

The aim of this study was to evaluate the role of magnesium levels on 3-year survival in the elderly with congestive heart failure (CHF) admitted to the Rehabilitative Cardiology Unit of S. Maugeri Foundation Scientific Institute of Telese/Campoli. All elderly patients > or = 65 years old with a diagnosis of CHF underwent clinical and instrumental examination, and their demographics, co-morbidity, and in-hospital and 3-year mortality rates were recorded. Hypomagnesemia was found in 4.8%, normomagnesemia in 67.5%, and hypermagnesemia in 27.8% of subjects. The hypomagnesemic group was excluded for numerical exiguity; the analysis was performed on a total of 199 elderly patients. Hypermagnesemia was found in 29.1% and normomagnesemia in 70.9%. At the univariate analysis no differences were found in hypermagnesemia in respect to normomagnesemia group, except for slightly higher levels of creatininemia (1.35 +/- 0.61 vs. 1.13 +/- 0.55 mg/dL, respectively; p < 0.02), greater disability (lost ADL, 2.69 +/- 1.57 vs. 2.15 +/- 1.56, respectively; p < 0.05), more mortality for CHF (32.6 vs. 48.3%; p < 0.05), and higher antacid and laxative use (82.7 vs. 24.8%, respectively; p < 0.0001). Patients with higher magnesium showed less probability to survive at a 3-year follow-up than did patients with lower levels (17.32 +/- 15.93 vs. 22.46 +/- 16.16 months; p < 0.05), and this finding remained significant in the multivariate analysis after adjusting for some confounders. Finally hypermagnesemia should also be considered in the absence of pre-existing renal failure clinical evidence because of its negative prognostic value, especially in elderly patients with CHF. The shown relationship between hypermagnesemia and laxative/antacid use should induce physicians to pay more attention to abuse of these drugs.

Circulatory collapse caused by unnoticed hypermagnesemia in a hospitalized patient

We report a case of hypermagnesemia in a hospitalized patient after prolonged laxative use; due to preexisting impaired consciousness and digestive problems, the hypermagnesemia was difficult to detect until it almost became fatal. A 64-year-old man who was a patient at another hospital for treatment of head injury and gastric ulcer had developed circulatory collapse and was transferred to our hospital. Hypermagnesemia (serum magnesium concentration 11.0 mg.dl(-1)) was thought to be the cause of the circulatory collapse and treatments were successful. A magnesium laxative had been administered for more than a month at the previous hospital, but the patient's serum magnesium level was never measured. Care should be taken when a magnesium laxative is administered to patients who already have impaired consciousness and digestive problems that are early symptoms of hypermagnesemia.

Hypermagnesemia induced by massive cathartic ingestion in an elderly woman without pre-existing renal dysfunction

A 76-year-old woman was referred to our hospital for unresponsiveness and hypotension. She had developed constipation that had led to ileus and had received 34 g of magnesium citrate (Magcolol P) orally the day before. She was lethargic, her blood pressure was less than 50 mmHg, and electrocardiogram (ECG) revealed sinus arrest with junctional escape rhythm. Her serum concentration of magnesium (Mg) was markedly elevated (16.6 mg/dl =13.7 mEq/l). Emergency colonoscopy revealed ischemic colitis. As her condition ameliorated, her renal function returned to normal. Hence, the present case suggests that severe hypermagnesemia can occur in the absence of pre-existing renal dysfunction in elderly patients with gastrointestinal diseases.