Association of ionized magnesium, total magnesium, gestational age, and intraventricular hemorrhage in preterm babies / 소아과

PURPOSE: The pathophysiology of magnesium, the second highest common compound in humans, is still unclear, especially in preterm babies. We accessed the association between total magnesium (tMg), ionized Mg (iMg), and gestational age (GA) and that between serum magnesium (sMg) and intraventricular hemorrhage (IVH) in preterm babies. METHODS: In all, 119 inborn preterm infants admitted between July 2006 and February 2008 were divided into the IVH group (19) and the control group (100) and were prospectively analyzed. TMg, iMg, pH, total calcium (tCa), and ionized Ca (iCa) levels were determined immediately after delivery or within 3 hours after birth, and their correlation with GA were investigated. RESULTS: TMg was not correlated with GA, tCa, iCa, and pH. IMg was correlated with tMg (r=0.288, P=0.002) and iCa (r=0.212, P=0.021); however, it was not correlated with GA and pH. Mean GA and birth weight were significantly lower (P=0.002) and smaller (P=0.030) in the IVH group. Mean sMg was higher in the IVH group (2.5+/-0.9 mg/dL) than in the control group (2.1+/-0.6 mg/dL) (P=0.021). SMg was a risk factor even after logistic regression analysis (OR, 2.798; 95% C.I., 1.265-6.192; P=0.011). CONCLUSION: In less than 37-week-old preterm babies, tMg and iMg were similar, regardless of GA. High sMg may be a risk factor for IVH in premature babies, regardless of their exposure to antenatal magnesium.

Changes in Ionized and Total Magnesium Concentration during Spinal Surgery / 대한마취과학회지

BACKGROUND: The incidence of postoperative hypomagnesemia in patients undergoing spinal surgery has been reported to be 70%. Ionized magnesium is considered to be the biologically active form, but until the early 1990s, only the total magnesium concentration could be measured. Currently, the ionized magnesium concentration as well as total magnesium concentration can be assessed due in part to the development of a selective electrode. The aim of this study was to more fully characterize the changes in the total and ionized magnesium concentrations in patients undergoing elective spinal fusion surgery. METHODS: The total and ionized magnesium, creatinine, albumin, urinary magnesium concentration, hematocrit, total amount of fluid administration, transfusion, blood loss, and urine output were evaluated both preoperatively and postoperatively in each patient. RESULTS: The total and ionized magnesium concentrations decreased from 0.783 mM/L and 0.529 mM/L preoperatively to 0.717 mM/L and 0.511 mM/L during the postoperative period, respectively. CONCLUSIONS: The incidence of total hypomagnesemia during spinal surgery was 15% but the incidence of ionized hypomagnesemia was only 3%.

Measurement of Serum Ionized Magnesium in Dialysis Patients / 대한신장학회잡지

BACKGROUND: Direct measurements of ionized magnesium (iMg) in serum by ion-selective electrodes have recently become available in clinical practice, and its usefulness needs to be investigated in dialysis patients because chronic renal failure is associated with disturbances in magnesium metabolism. METHODS: We measured serum iMg in 29 hemodialysis (HD) patients and 24 peritoneal dialysis (CAPD) patients using an ion-selective electrode. The results were compared with those from 30 age- matched control patients who were admitted due to non-renal diseases and were confirmed to have normal serum total magnesium (tMg) levels. RESULTS: Serum tMg was significantly higher in both HD (0.95 [0.81-1.06] mmol/L) and CAPD (0.86 [0.74-0.99] mmol/L) patients compared with the controls (0.74 [0.70-0.78] mmol/L). Serum iMg was significantly higher in HD patients (0.65 [0.60-0.72] mmol/L) compared with the controls (0.55 [0.51-0.57] mmol/L), but was not higher in CAPD patients (0.54 [0.50-0.60] mmol/L). Thus, the ionized fraction of serum magnesium (iMg/tMg) was significantly lower in CAPD patients (65.3 [58.8-68.2]%), but not in HD patients (68.7 [63.6-77.0]%), compared with the controls (72.2 [67.2-78.3]%). In dialysis patients, iMg/ tMg was significantly lower in those with residual renal function than in anuric patients (67.5 [63.6-74.8]% vs. 61.4 [56.4-70.7]%). CONCLUSION: In current practice, true hypermagnesemia may exist frequently in HD patients (at predialysis), but not in CAPD patients. The ionized fraction of serum magnesium may be reduced in CAPD patients, but not in HD patients.

Apoptotic Change in Response to Magnesium Therapy after Moderate Diffuse Axonal Injury in Rats

The biochemical factors related to moderation of secondary or delayed damage to the central nervous system (CNS) remain undefined. We have recently demonstrated that the weight- drop induced moderate diffuse axonal injury (mDAI) in rats causes a rapid decline in serum ionized magnesium (Mg2+) and a significant increase in the amount of serum ionized calcium (Ca2+) relative to Mg2+ (Ca2+/ Mg2+). For three hours, serum Mg2+ levels remained significantly depressed at 76% of preinjury values (p 0.05). Head trauma resulted in a small decrease of Ca2+ (about 10%), but a significant increase in the amount of Ca2+/Mg2+ (mean value in control group: in injured group for 3 hours after trauma =4.65 +/-0.012 : 5.69 +/-0.015, p< 0.05) was observed. In order to further investigate the relationship between Mg2+ and brain injury, the effect of Mg2+ treatment on posttraumatic histological changes (apoptotic changes) was examined following the weight-drop induced brain injury. At 30 min postinjury, animals treated with MgSO4 (750micro Ml/kg) showed significant improvements of apoptotic changes when compared to the control group (54.8 +/- 1.7, 51.5 +/- 3.2 at 12, 24 h in control group, 24.8 +/- 2.6, 20.5 +/- 1.4 at 12, 24 h in treated group, p< 0.05). The early decline in serum Mg2+ and the increase in the amount of Ca2+/Mg2+ immediately following brain trauma uncovered by these findings suggest that they may be a critical factor in the development of irreversible tissue injury. If this proves to be the case, treatment with MgSO4 may be effective in improving histological findings following experimental traumatic brain injury in rats.

Change in Serum Concentration of Magnesium and Calcium Ions Following Moderate Diffuse Axonal Injury in Rats: Preliminary Study

OBJECTIVE: Traumatic brain injury has been shown to result in a decrease of the brain-free magnesium concentration that is associated with the development of neurologic deficits. However, changes in free magnesium homeostasis have not been characterized in other fluid compartments. We examine the ionized serum magnesium(Mg2+) and ionized serum calcium(Ca2+) in the moderate diffuse axonal injury of rat model. METHODS: We designed a study to determine whether ionized serum magnesium(Mg2+) and / or ionized serum calcium(Ca2+) levels correlate with moderate diffuse axonal injury(mDAI). A new ion-selective electrode was used to determine Mg2+ and Ca2+ level in the serum, prior to and following weight-drop induced mDAI. RESULTS: Serum Mg2+ remained significantly depressed to about 76% of preinjury values for 3 hours (0.73+/-0.01 mg/dL, 0.79+/-0.03 mg/dL, 0.84+/-0.03 mg/dL at 1, 2, 3 hours after trauma, respectively) compared to control group (1.07+/-0.03 mg/dL, p<0.05), but not in total serum magnesium(tMg). Mg2+/ tMg was shown a significant decrease for first 3 hours (49%, 53.4%, 56.4% at 1, 2, 3 hours after trauma respectively) compared to control group (70.9%, p<0.05). Head trauma resulted in small decrease of Ca2+, but there was a significant increase in the amount of Ca2+/ Mg2+(mean value in control group: in injured group for 3 hours after trauma = 4.65+/-0.012: 5.71+/-0.015, p<0.05). Apoptotic change was shown at 3 hours after mDAI and apoptotic index(AI) was significantly increased at 12 and 24 hours after trauma (54.8+/-1.7, 51.5+/-3.2 at 12, 24 hours, p<0.05). CONCLUSION: These findings suggest that the early decline in serum Mg2+ and increase in the amount of Ca2+/ Mg2+ following brain trauma may be a critical factor in the development of irreVersible tissue injury and early treatment with magnesium salt may be effective in histological changes following experimental traumatic brain injury in the rat.