Serum ionized magnesium and calcium levels in adult patients with seizures

Objective. Prior studies have been equivocal about whether or not serum levels of the divalent ions calcium and magnesium are altered during different types of seizures. Magnesium is a potential modulator of seizure activity because of its ability to antagonize the excitatory calcium influx through the N‐methyl‐D‐aspartate (NMDA) receptor. We hypothesize that serum ionized levels of calcium (Ca²⁺) and magnesium (Mg²⁺) would be altered significantly during certain types of seizures. Material and methods. A convenience sample of seizure patients presenting to an emergency department (ED) were enrolled in this prospective study. Novel ion‐selective electrodes were used to measure Ca²⁺ and Mg²⁺. Data were reported as mean values±standard deviations. Group comparisons were analyzed by ANOVA with post‐hoc testing using the Bonferroni, or the Fisher exact test, where appropriate, α = 0.05 (two‐tailed). Results. Forty‐nine patients with seizure and 32 healthy racially matched controls were included in the study. Seizure patients had a significantly (p<0.001) lower mean Mg²⁺, but not total serum Mg and a significantly (p<0.001) higher Ca²⁺/Mg²⁺ ratio than that in controls. Conclusions. We were able to show significantly lower Mg²⁺ and higher ionized Ca²⁺/Mg²⁺ ratios in seizure patients compared with a racially matched control group.     

Serum ionized magnesium levels and serum ionized calcium/ionized magnesium ratios in women with menstrual migraine

OBJECTIVE: It has been suggested that magnesium deficiency may play an important role in menstrual migraine and that the serum ionized calcium (ICa2+)/ionized magnesium (IMg2+) ratio is important in migraine headache. Studies were designed to test these hypotheses. DESIGN: We prospectively evaluated 270 women seen at a headache clinic and in 61 women with menstrual migraine measured IMg2+, total magnesium, and ICa2+ levels so as to calculate the ICa2+/IMg2+ ratio. RESULTS: The incidences of IMg2+ deficiency were 45% during menstrual attacks, 15% during nonmenstrual attacks, 14% during menstruation without a migraine, and 15% between menstruations and between migraine attacks. The serum ICa2+ levels were within our reference range, but the ICa2+/IMg2+ ratio was elevated (P<.01) in menstrual migraine. CONCLUSIONS: The high incidence of IMg2+ deficiency and the elevated ICa2+/IMg2+ ratio during menstrual migraine confirm previous suggestions of a possible role for magnesium deficiency in the development of menstrual migraine.     

Ionized magnesium levels and the ratio of ionized calcium to magnesium in asthma patients before and after treatment with magnesium

Objective. Prior studies have been equivocal about the efficacy of magnesium therapy in acute asthma exacerbations. We hypothesize that pretreatment ionized magnesium (Mg²⁺) levels and/or the ratio of ionized calcium to ionized magnesium (Ca²⁺/Mg²⁺) may have been confounding variables in these previous studies. Here, we report on the incidence of abnormal divalent ion levels in our asthma population. Material and methods. The study was designed as a randomized, double‐blind, placebo‐controlled trial of intravenous magnesium. Inclusion criteria were: age >18 years, percentage predicted forced expiratory volume (FEV₁) <75 % after an initial beta‐agonist. African–American patients (AA) at an urban university hospital were randomized to 2?g IV Mg or placebo. Mg²⁺ and Ca²⁺/Mg²⁺ levels were measured pre‐ and post‐infusion. Data were reported as means±SD. Student's t‐test and Fisher's exact test were used where appropriate (α = 0.05, two tailed) Results. Fifty‐five AA patients (mean age of 42.7 years±15.6 years, range18–75 years) were studied. A significantly (p<0.05) lower level of Mg²⁺ was found in asthma (AS) patients compared with that in the AA group, by 0.03?mmol/L (95 % CI, 0.007–0.053?mmol/L). The AS group had a mean increase in Ca²⁺/Mg²⁺ ratios over the AA group, of 0.27 (95 % CI, 0.16–0.38); 100 % of patients with abnormal divalent ion levels were corrected with IV magnesium. Conclusions. We identified a subgroup of asthmatic patients with significant abnormalities in their divalent ion concentrations, which was corrected with IV magnesium.     

Ionized magnesium levels and the ratio of ionized calcium to magnesium in asthma patients before and after treatment with magnesium

OBJECTIVE: Prior studies have been equivocal about the efficacy of magnesium therapy in acute asthma exacerbations. We hypothesize that pretreatment ionized magnesium (Mg(2+)) levels and/or the ratio of ionized calcium to ionized magnesium (Ca(2+)/Mg(2+)) may have been confounding variables in these previous studies. Here, we report on the incidence of abnormal divalent ion levels in our asthma population. MATERIAL AND METHODS: The study was designed as a randomized, double-blind, placebo-controlled trial of intravenous magnesium. Inclusion criteria were: age >18 years, percentage predicted forced expiratory volume (FEV(1)) <75 % after an initial beta-agonist. African-American patients (AA) at an urban university hospital were randomized to 2 g IV Mg or placebo. Mg(2+) and Ca(2+)/Mg(2+) levels were measured pre- and post-infusion. Data were reported as means+/-SD. Student's t-test and Fisher's exact test were used where appropriate (alpha = 0.05, two tailed). RESULTS: Fifty-five AA patients (mean age of 42.7 years+/-15.6 years, range 18-75 years) were studied. A significantly (p<0.05) lower level of Mg(2+) was found in asthma (AS) patients compared with that in the AA group, by 0.03 mmol/L (95 % CI, 0.007-0.053 mmol/L). The AS group had a mean increase in Ca(2+)/Mg(2+) ratios over the AA group, of 0.27 (95 % CI, 0.16-0.38); 100 % of patients with abnormal divalent ion levels were corrected with IV magnesium. CONCLUSIONS: We identified a subgroup of asthmatic patients with significant abnormalities in their divalent ion concentrations, which was corrected with IV magnesium.     

The simultaneous measurement of ionized and total calcium and ionized and total magnesium in intensive care unit patients

PURPOSE: This study was undertaken to determine the relationship between total magnesium and ionized magnesium in critically ill and injured patients. METHODS: Eighty consecutive intensive care unit (ICU) admissions were evaluated and 34 patients were enrolled in the study. Patients were enrolled who had indwelling arterial catheters and were within 4 days of ICU admission. Six milliliters of blood was collected and assayed simultaneously for total and ionized magnesium, total and ionized calcium, and albumin level. An Acute Physiology and Chronic Health Evaluation (APACHE II) score was calculated at the time of blood collection. RESULTS: The results of our study show a strong correlation between ionized and total magnesium (R =.903) that was not seen between ionized and total calcium (R =.748). We found total hypomagnesemia in 18% and ionized hypomagnesemia in 21% of ICU patients. We also found that 14.7% (5 of 34) of our patients had ionized hypermagnesemia whereas none displayed total hypermagnesemia. We did not find a correlation between APACHE II, sex, race, albumin level, and any electrolyte level. The mortality rate in the subjects studied was 21% (7 of 34). CONCLUSIONS: Based on our results we would recommend that intensivists directly measure ionized calcium whereas ionized magnesium can be inferred from total magnesium.     

Foscarnet-induced changes in plasma concentrations of total and ionized calcium and magnesium in HIV-positive patients

The time course and magnitude of foscarnet-induced changes in plasma concentrations of total and ionized calcium and magnesium were investigated in 13 male HIV-positive patients who had no active cytomegalovirus-associated disease. The patients had a mean age of 36 years (range 25-49 years) and a mean CD4 cell count of 550 cells/mm3 (range 130-1280 cells/mm3). Peak (mean +/- SD) plasma concentrations of foscarnet (0.89+/-0.10 mmol/l) were seen at the end of the period of drug infusion (90 mg/kg of foscarnet was infused over 2 hours) and declined with a terminal half-life of 5.7+/-0.7 hours. Plasma concentrations of total calcium declined over an 8-hour period, with the lowest concentration occurring after 4 hours (baseline: 2.29+/-0.09 mmol/l; lowest: 2.18+/-0.07 mmol/l; P < 0.001). By contrast, the lowest plasma concentration of ionized calcium occurred after 2 hours (baseline: 1.25+/-0.04 mmol/l; lowest: 0.99+/-0.05 mmol/l; P < 0.001), before gradually recovering to baseline levels over the next 10 hours. The mean maximal decrease in total calcium was 0.11+/-0.06 mmol/l, compared with 0.26+/-0.04 mmol/l for ionized calcium (P < 0.001). Plasma concentrations of total magnesium declined from 0.79+/-0.06 mmol/l (baseline) to 0.74+/-0.04 mmol/l (P < 0.05) after 4 hours and remained at this level after 8 hours. However, plasma concentrations of ionized magnesium fell steeply from 0.56+/-0.03 mmol/l to 0.39+/-0.03 mmol/l at 2 hours (P < 0.001), followed by a gradual recovery over the next 10 hours. The mean maximal decrease in total magnesium was 0.05+/-0.08 mmol/l, compared with 0.18+/-0.03 mmol/l (P < 0.001) for ionized magnesium. In summary, we found that foscarnet-induced changes in the plasma concentrations of total calcium and magnesium were dissociated from the corresponding changes in ionized calcium and magnesium. The maximal decreases in the plasma concentrations of total calcium and magnesium were smaller in magnitude and occurred much later than did the changes in ionized calcium and magnesium. The relative changes in the plasma concentration of ionized magnesium were greater than those of ionized calcium, indicating that foscarnet binds preferentially to the magnesium ion.     

Serum ionized calcium by specific ion electrode

In 30 normal subjects whose sera were measured at 27° the pH was 7.46 ± 0.06 and the ionized calcium concentration by electrode was 3.86 ± 0.18 mg%. The precision was a relative S.D. of 2.2%. A series of reconstituted samples indicates that sera can be stored for several days in a refrigerator and if the pH is precisely restored to the fresh value by equilibration with carbon dioxide, the fresh ionized calcium will be restored.     

Serum and salivary magnesium levels in migraine and tension-type headache. Results in a group of adult patients

It has been suggested that magnesium plays a central role in different etiopathogenetic conditions involved in the onset of migraine. We measured, by atomic absorption spectrophotometry, serum and salivary magnesium levels in drug-free migraine patients with and without aura and in tension-type headache patients. Migraine sufferers with and without aura and tension-type headache had significantly lower levels of serum and salivary magnesium concentrations in the interical periods than a group of healthy young individuals. Serum magnesium levels tended to be further reduced during attacks in all patient groups studied. A statistically significant decrease in salivary magnesium levels was evident only for migraine patients with aura. Serum magnesium levels and to a lesser extent salivary magnesium levels might express indirectly the lowering of brain extracellular magnesium concentration which occurs in migraine patients both in the intererictal periods and ictally.     

Plasma ionized calcium in brain-dead patients

Background The mechanism of brain death-induced myocardial dysfunction remains debatable. Hypocalcemia is known to induce reversible myocardial dysfunction. However, the incidence of hypocalcemia and its effect on myocardial function during brain death is unknown.Methods In 54 consecutive braindead patients, we measured plasma total and ionized calcium concentrations, QT and corrected QT intervals, and left ventricular ejection fraction area (LVEFa), using transesophageal echocardiography.Results 49 (91%) of brain-dead patients had a decrease in total plasma total calcium concentration but only 19 (35%) had a decrease in plasma ionized calcium. Corrected total plasma calcium failed to predict ionized calcium concentration and QT intervals were not significantly different in normo and hypocalcemic patients. The LVEFa was not significantly different between normo and hypocalcemic patients (53±13 versus 50±20%), and no correlation was found between LVEFa and ionized calcium (R=0.02, NS). Hypocalcemic patients required greater doses of dopamine (8.2±5.2 versus 5.0±3.4 g·kg^–·min^–1,p<0.02) to maintain arterial pressure. Hypocalcemia was associated with a higher volume loading and a lower plasma protide concentration which reflected hemodilution.Conclusion A decrease in plasma ionized calcium is not frequent, rarely severe, and probably not the main mechanism of myocardial dysfunction in brain-dead patients. Hypocalcemic patients required higher doses of dopamine, suggesting a decrease in systemic resistance. Only direct measurement of ionized calcium can assess plasma calcium ion status in brain-dead patients.     

Evaluation of AVL988/4 analyzer for measurement of ionized magnesium and ionized calcium

Ionized magnesium (Mg⁺⁺) and ionized calcium (Ca⁺⁺) are the physiologically active forms of these elements in the body and their concentrations have clinical value. Though the AVL988/4 instrument that measures concentrations of Mg⁺⁺ and Ca⁺⁺ has been evaluated, some clinically important parameters were unknown. In this study, we evaluated AVL988/4 analyzer for measuring Mg⁺⁺ and Ca⁺⁺ concentrations and provided the following information: (1) The newly formulated Becton Dickinson (BD) Vacutainer plastic tubes with clot activator and silicone as the stopper lubricant (serial no. 367820) caused a significant high bias for the Mg⁺⁺ measurement but had no effect on the Ca⁺⁺ measurement; (2) the optimal conditions for specimen storage were no exposure to air at 4°C for up to 24 h; (3) no significant difference in the results of the Ca⁺⁺ concentration determined using AVL988/4 or i-STAT; (4) no carryover between samples was found.     

Evaluation of AVL988/4 analyzer for measurement of ionized magnesium and ionized calcium

Ionized magnesium (Mg++) and ionized calcium (Ca++) are the physiologically active forms of these elements in the body and their concentrations have clinical value. Though the AVL988/4 instrument that measures concentrations of Mg++ and Ca++ has been evaluated, some clinically important parameters were unknown. In this study, we evaluated AVL988/4 analyzer for measuring Mg++ and Ca++ concentrations and provided the following information: (1) The newly formulated Becton Dickinson (BD) Vacutainer plastic tubes with clot activator and silicone as the stopper lubricant (serial no. 367820) caused a significant high bias for the Mg++ measurement but had no effect on the Ca++ measurement; (2) the optimal conditions for specimen storage were no exposure to air at 4 degrees C for up to 24 h; (3) no significant difference in the results of the Ca++ concentration determined using AVL988/4 or i-STAT; (4) no carryover between samples was found.     

Hair calcium and magnesium levels in patients with fibromyalgia: a case center study

BACKGROUND: Fibromyalgia is not an uncommon condition. Because its cause has yet to be identified. treatment of the condition has been empirical; frequently, outcomes are unsatisfactory. Some patients with fibromyalgia were observed to have high hair calcium and magnesium levels compared with healthy subjects. Because of this and because supplementing calcium with magnesium to fibromyalgia subjects reduced the number of tender points detected by digital palpation, it is worth investigating if patients with fibromyalgia have significantly higher hair calcium and magnesium levels than their healthy counterparts. OBJECTIVES: To determine the degree of difference between the hair calcium and magnesium levels in patients with fibromyalgia and in healthy subjects. METHODS: The study was retrospective and of paired design. Twelve patients who had hair analysis performed and met the criteria of fibromyalgia defined by American College of Rheumatology (1990) were selected consecutively from clinical files. These patients were then matched by age and sex to 12 healthy subjects selected consecutively from the same patient files who had hair analysis performed for checkup purposes. Nonparametric Wilcoxon rank sum tests were used to determine if the hair calcium and magnesium levels in patients with fibromyalgia were significantly higher than that of the control subjects. RESULTS: Wilcoxon rank sum tests showed that patients with fibromyalgia had significantly higher calcium and magnesium levels than the control subjects at alpha = .025 and .05, respectively. CONCLUSION: In the presence of high hair calcium and magnesium levels, calcium and magnesium supplements may be indicated as an adjunctive treatment of fibromyalgia.     

Total and ionized serum magnesium in critically ill patients

Objective To assess the alterations in total serum magnesium (tsMg) and ionized serum magnesium (Mg²⁺) and their association with prognosis in critically ill patients.Design and setting Prospective, cohort study in the intensive care unit (ICU) of a university teaching hospital.Patients Adult patients admitted to the ICU without previous factors influencing magnesium homeostasis were included during a 6-month period.Measurements and results One hundred forty four patients were included. Mean age was 60.6±15.4 years; mean APACHE II score was 12.6±6.9. Blood samples were collected in the first 24 h after ICU admission and again on the second, third, and last days of stay in the ICU. At ICU admission 52.5% had total hypomagnesemia and 13.5% total hypermagnesemia; with respect to the Mg²⁺ 9.7% showed ionized hypomagnesemia and 23.6% ionized hypermagnesemia. Patients who developed ionized hypermagnesemia had higher mortality than patients without ionized hypermagnesemia development (P=0.04). A moderate correlation between tsMg and Mg²⁺ concentrations was found; however, a number of patients with total hypomagnesemia (69–85% during the study) had ionized normomagnesemia. The measure of agreement between tsMg and Mg²⁺ levels was poor.Conclusions Magnesium alterations are frequently found in critically ill patients. The usually determined tsMg levels are not a reflection of Mg²⁺ levels. Development of ionized hypermagnesemia is associated with prognosis.     

Serum ionized calcium and parathyroid hormone in renal stone disease.

Serum ionized calcium was shown to be significantly elevated in a group of twenty-eight subjects with idiopathic hypercalciuria in whom the mean total serum calcium concentration was within normal limits. Measurement of parathyroid hormone levels confirmed that elevated values are suppressible by infusion of calcium. Ten subjects with simultaneous elevation of serum ionized calcium and parathormone levels above 3 S.D. of normal were referred for neck exploration, and a parathyroid adenoma was found and removed in nine. Significant decreases to normal values of serum ionized calcium and parathormone levels of urine and calcium excretion were documented some weeks following operation. The results conflict with both the alimentary calcium hyperabsorption theory and the renal calcium leak theory of the aetiology of idiopathic hypercalciuria, and support the possibility that idiopathic hypercalciuria in many cases represents an early or mild form of 'normocalcaemic' primary hyperparathyroidism.     

Ionized magnesium supplementation in critically ill patients: comparing ionized and total magnesium

PURPOSE: The purpose of this study was to assess the effect of magnesium supplementation on total magnesium, ionized magnesium, ionized calcium, potassium, and pH in critically ill cancer patients and to compare the validity of the measurements. MATERIALS AND METHODS: Thirty-three consecutive critically ill patients receiving magnesium supplementation were placed in this prospective observational study at the Comprehensive Cancer Center, University Hospital. One gram (4.1 mmol) magnesium in 50 mL D5W was administered to critically ill patients, and the following were measured: total magnesium, ionized magnesium, ionized calcium, potassium, albumin, pH, BUN, creatinine, creatinine. RESULTS: Total magnesium and ionized magnesium increased by a mean of .11 +/- .02 and .05 +/- .01 mmol/L, respectively, after supplementation with 4.1 mmol of magnesium sulfate (P = .0001).Total magnesium, ionized magnesium, albumin, ionized calcium, potassium, and pH did not change significantly by the administration of 1 g of magnesium sulfate. CONCLUSION: The mean ionized magnesium (IMg+2) relationship to total magnesium (TMg) cannot be predicted before the supplementation with the available technology. After supplementation of 4.1 mmol/L the ionized magnesium level increased by .05 +/- .01 mmol/L. Magnesium supplementation had no significant effect on ionized calcium, potassium, and pH. TMg and IMg+2 should be followed independently.     

Serum ionized magnesium: comparison of results obtained with three ion-selective analyzers.

In a two-center (Academic Medical Center, The Netherlands, and National Institutes of Health, USA) study, we compared ionized magnesium (iMg2+) results in serum determined with the AVL 988/4, KONE Microlyte 6 and NOVA CRT, which are the currently available analyzers equipped with a magnesium ion-selective electrode. The comparison was performed with frozen serum samples from normal individuals and patients. Imprecision and reference intervals were established. We found the best agreement between the KONE(x) and AVL(y) magnesium ion-selective electrodes (y= 0.972x-0.013; n=138) with samples from patients. With samples from normals, all three analyzers reported significantly different results (p<0.05). Best precision was found using the NOVA; coefficients of variation established at three levels were all < 4.0%. Coefficients of variation for the AVL and KONE were <5% at normal and high iMg2+, but 10.7 and 9.4%, respectively, at iMg2+ approximately 0.30 mmol/l. The reference intervals (mean+/-standard deviation) based on measurements in fresh serum samples were different for each analyzer: 0.55-0.63 mmol/l for AVL, 0.470.57 mmol/l for KONE and 0.43-0.55 mmol/l for NOVA. Thus, significant differences among the ionized magnesium concentration obtained with the three analyzers, limit comparison of results in clinical practice, and need to be resolved (e.g. by improvement of specificity and standardization of calibrators).     

Serum ionized calcium, intact PTH and novel markers of bone turnover in bedridden elderly patients

Abstract. Chronic immobilization could markedly affect calcium and bone metabolism in elderly people. To investigate this, and to test the theory of ‘type II’ osteoporosis in bedridden elderly patients with low vitamin D status, 55 such subjects were examined. Serum concentrations of ionized calcium (Ca⁺⁺), intact parathyrin (PTH) and two novel markers of bone collagen formation (carboxyterminal propeptide of type I procollagen; PICP) and resorption (carboxyterminal crosslinked telopeptide of type I collagen; ICTP) were measured. The effects on these parameters after 40 weeks of supplementation with vitamin D (1000 IU d^-1) and/or calcium (1g d^-1) were subsequently prospectively evaluated. Despite low (mean 11·6 nmol l^-1) serum 25-hydroxyvitamin D levels (25-OHD), those of 1,25-dihydroxy-vitamin D (1,25-(OH)₂D) were mostly normal. Neither correlated with Ca⁺⁺ or PTH. PTH correlated negatively not only with Ca⁺⁺ (r=–0·328, P < 0·05) but also with ICTP (r=–0·306, P < 0·05). Mean PICP was normal but ICTP was elevated and tended to correlate positively with Ca⁺⁺ (r=–0·268, P= 0·06). Vitamin D supplementation did not change PICP or ICTP considerably, despite slightly increased 1,25-(OH)₂D and slightly decreased PTH. Ca⁺⁺ values were normal and remained stable. In conclusion, Ca⁺⁺ and PTH are poor indicators of vitamin D status in chronically immobilized elderly subjects. Furthermore, the results suggest that the increased bone resorption is not due to ‘type II’ secondary hyperparathyroidism; rather the resorption is primarily increased. Correction of vitamin D deficiency does not seem to benefit ageing bones unless adequate mechanical loading is provided.