Serum Ionized Magnesium Levels Research Articles

Risk of Pre-Eclampsia in Women with Low Serum Ionized Magnesium

Background: There are many risk factors of development of preeclampsia among the pregnant women. Objective: The purpose of the present study has set out to assess the relationship between preeclampsia and blood ionized magnesium levels.
 Methodology: This case-control study was performed in the Department of Obstetrics and Gynaecology, Dhaka Medical College and Hospital from January 2020 to December 2021 for a period of 2(two) years. Pregnant patients who showed preeclampsia were all the amounts of ionized magnesium in venous blood collected from patients with preeclampsia. Additionally, the magnesium levels of age-matched, healthy pregnant women were determined.
 Results: A total number of 100 pregant women included in this study of which 50 pregnant women were designated as case and the rest 50 pregnant women were control. It has found that serum levels of ionized magnesium were significantly decreased among preeclamptic cases (0.58 ± 0.06) as compared to normal pregnancies (0.72 ± 0.05) (p < 0.001). Using a cut-off value of 0.7 mmol/l, the serum ionized magnesium level was divided into two groups and was compared between cases and controls. The risk of developing preeclampsia was more than 33 (95% CI = 10.9 – 102.1) times higher in pregnant women with serum magnesium level < 0.7 mmol/L than those pregnant women with serum magnesium level 0.7 or > 0.7 mmol/L.
 Conclusion: Low level of serum ionized magnesium is a risk factor of development of preeclampsia.

The advantages of measuring the serum ionized magnesium level when performing cardiac surgery

The advantages of measuring the serum ionized magnesium level when performing cardiac surgery

Effect of phototherapy on serum magnesium level in newborn with hyperbilirubinemia

Objective To screen neonates with hyperbilirubinemia who received phototherapy to determine the effect of phototherapy on the serum magnesium level. Background Hyperbilirubinemia is one of the most prevalent problems in neonates. Phototherapy remains the main primary management in neonatal jaundice. However, it has many adverse effects, and hypomagnesemia is one of them. Patients and methods A prospective hospital-based comparative study was conducted on 70 eligible neonates admitted in Neonatal Intensive Care Units of Menoufia University Hospital receiving phototherapy from May 2019 to February 2020. Serum bilirubin and magnesium (total and ionized) were determined before starting phototherapy, and it was considered as control. Then serum bilirubin and magnesium were measured after 48 h of phototherapy and after termination of phototherapy. The plasma magnesium level was measured spectrophotometrically using ready-for-use kit supplied by Quimica Clinica Aplicada S.A. Company. Results The total serum magnesium level before phototherapy was 2.7 ± 0.3, 2.1 ± 0.30 mg/dl 48 h after phototherapy, and 1.85 ± 0.28 mg/dl after termination of phototherapy. Serum ionized magnesium level before phototherapy was 0.58 ± 0.02, 0.53 ± 0.02 mmol/l 48 h after phototherapy, and 0.51 ± 0.01 mmol/l after termination of phototherapy. So, there was a significant decrease in serum magnesium level (total and ionized) after phototherapy. Conclusion Our study concluded that there was a significant negative correlation between the duration of phototherapy and serum magnesium level (total and ionized).

Effects of Magnesium Sulphate on the Onset and Duration of Neuromuscular Blockade by Cisatracurium in Adult Patients Undergoing Transpedicular Screw Fixation Surgery Under General Anesthesia

Background: In the past, various drugs have been used to potentiate the effects of non-depolarizing neuromuscular blocking agents. Among these agents, Magnesium Sulphate has been found to be effective and safe. In our part of the world, Cisatracurium had not been used commonly until recently when its availability has made possible its use as a long-term non-depolarizing neuromuscular blocking agent. So, we decided to use MgSo4 with cisatracurium to see its effectiveness in patients undergoing transpedicular screw fixation surgery. Objective: To compare the onset, duration of action and mean intraoperative consumption of Cisatracurium in adult patients undergoing Transpedicular screw fixation (TPSF) surgery under general anesthesia with and without pretreatment as well as intraoperative use of Magnesium sulphate. Study Design: A Randomized Controlled study. Settings: Department of Orthopedics & spine Centre, Ghurki Trust Teaching Hospital (GTTH), Lahore Pakistan. Duration: Six months from 1st June 2019 to 30th November 2019. Methodology: In this study, 46 patients were randomly divided into two groups by lottery method (23 in each group). In both groups, patients either received magnesium sulphate (Mgso4) 50 mg/kg in 100 ml of 0.9% Normal saline or 100 ml of only 0.9% Normal saline intravenously 20 minutes before induction of general anesthesia with Propofol, Fentanyl and Cisatracurium. After induction of general anesthesia, group M received continuous infusion of Mgso4 (20 mg/kg/hr) until the beginning of skin closure. Maintenance dose of Cisatracurium was given when first twitch was noted by Train-of-Four. Time of onset, duration of neuromuscular blockade and total intra-operative consumption of Cisatracurium were noted. Heart rate, mean arterial blood pressure and serum ionized Magnesium levels were also measured. Results: Time of onset was significantly shorter in the group M than group N (P 0.05). Conclusion: Magnesium impairs neuromuscular transmission at blood levels that did not affect hemodynamics and significantly augments the neuromuscular blockade by Cisatracurium.

Association of Low Serum Ionized Magnesium Level with Fever-Triggered Seizures in Epileptic Children

Purpose: Several studies have shown that magnesium plays an important role in modulating N-methyl-D-aspartate (NMDA)-related seizures by blocking NMDA...

Measuring Serum Level of Ionized Magnesium in Patients with Migraine.

Migraine is known as one of the most disabling types of headache. Among the variety of theories to explain mechanism of migraine, role of serum magnesium is of great importance. Serum magnesium, as a pathogenesis factor, was considerably lower in patients with migraine. We established this study to see if serum ionized magnesium, not its total serum level, was different in migraineurs from normal individuals. In this case control study, all participants were recruited from Neurology Clinic of Imam Hossein Hospital, Tehran, Iran. Ninety-six people were entered in the study, 48 for each of case and control groups. The two groups were matched by age and sex. Migrainous patients were selected according to the criteria of International Headache Society. Various characteristics of headache were recorded based on patients' report. Controls had no history of migraine or any significant chronic headaches. Serum ionized magnesium level was measured in both of the case and control groups and the results were compared to each other. P value of <0.05 was considered as significant. Case group consisted of 13 males, 35 females, and control group included 14 males, as well as 34 females. Mean age was 33.47± 10.32 yr for case and 30.45 ±7.12 yr for control group. Twenty-eight patients described the intensity of their headaches as moderate; 15 patients had severe and the 5 remainders had only mild headaches. Mean serum level of ionized Mg was 1.16± 0.08 in case group and 1.13± 0.11 in control group of no significant difference (P >0.05). Serum ionized magnesium, which is the active form of this ion, was not significantly different in migraineurs and those without migraine. This may propose a revision regarding pathogenesis of migraine and question the role of magnesium in this type of headache.

Correlation to Serum Ionized Calcium and Magnesium Concentration with Sympathetic Nerve Functions in Type 2 Diabetes Mellitus

Background : In type 2 DM, a metabolic disorder causes disturbances of different metabolic processes of the body including electrolyte imbalance. Therefore changes in serum level of Ca2+ and Mg2+ may have some relationship to the occurrence of neuropathy. Objective : The study has been designed to observe the sympathetic nerve function status in type 2 diabetic subjects in order to assess the relationship between serum ionized calcium &amp; magnesium. Study design : This cross section study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. Forty seven type 2 diabetic subjects were included in two groups. Group B consisted of 25 recently diagnosed diabetic subjects aged 40-68 years and group C consisted of 22 subjects having duration of diabetes for 10-20 years. Twenty five (25) age and BMI matched healthy subjects were included in group A (non-diabetic) for control. Methods : Sympathetic nerve function were assessed by two simple non-invasive cardiovascular reflex tests. These were systolic blood pressure, response to lying to standing up and diastolic blood pressure response to distain hand grip test. Ionized serum calcium and magnesium were measured by ion sensitive electrode method using NOVA electrode. Data were analyzed by ‘t’ test, Pearson’s correlation co-efficient. Results: Serum ionized calcium levels were significantly higher in both the diabetic group B (P&lt;0.001) and C (P&lt;0.001) than that of control group A. Serum ionized magnesium level was significantly higher in diabetic group C (P&lt;0.001) compared to that of control group A. Pearson’s correlation of ionized calcium and magnesium with sympathetic nerve function parameters were done. Statistically significant relation was found in group B between sustained hand grip test with ionized calcium and in group C between systolic blood pressure response to standing with ionized magnesium. Conclusion : Serum ionized calcium &amp; magnesium level was increased in type 2 diabetic patients irrespective of duration and some correlation was found with sympathetic nerve function parameters DOI: http://dx.doi.org/10.3329/updcj.v3i2.17991 Update Dent. Coll. j: 2013; 3 (2): 03-08

Serum Ionized Magnesium Levels in Relation to Metabolic Syndrome in Type 2 Diabetic Patients

Objective: To evaluate circulating serum ionized magnesium (i-Mg) concentrations in patients with type 2 diabetes mellitus, and to investigate its relationship with the components of the metabolic syndrome.Design: cross-sectional study.Setting: Outpatients’ service for diabetic patients at the University Hospital of Messina, Italy.Subjects: 290 patients with type 2 diabetes mellitus.Measures of Outcome: Serum i-Mg was measured by ion selective electrode. Age, gender, body mass index (BMI), waist circumference, blood pressure, fasting glucose, HbA1c, HDL cholesterol, triglycerides, and urinary albumin excretion rate (UAER) were considered in the analyses. Patients with hypomagnesemia, defined as serum i-Mg <0.46 mmol/l, were compared with those having normal serum i-Mg levels, and variables proven to be associated with low i-Mg levels in the univariate analysis were entered in a multivariable logistic regression model to obtain a deconfounded estimate of the association between metabolic parameters and hypomagnesemia.Results: In univariate analysis, serum i-Mg levels were significantly reduced in patients with low HDL cholesterol, high triglycerides values, high waist circumference, high blood pressure, microalbuminuria and clinical proteinuria. Hypomagnesemia was highly prevalent in our study population (N = 143, 49.3%). After adjusting for potential confounders, plasma triglycerides (OR = 4.71; 95% CI = 2.56–8.67), waist circumference (OR = 2.21; 95% CI = 1.21–4.04), microalbuminuria (OR = 2.43; 95% CI = 1.16–5.08) and clinical proteinuria (OR = 2.04; 95% CI = 1.02–5.68) were independently associated with hypomagnesemia.Conclusions: Hypomagnesemia is highly prevalent in diabetic outpatients. High plasma triglycerides, waist circumference and albuminuria are independent correlates of hypomagnesemia.

Influence of air exposure and storage condition on serum ionized magnesium level

The aim of this study was to evaluate whether reporting serum level of ionized magnesium (iMg) is appropriate when affected by various conditions such as exposure to air and delayed measurement. Serum levels of pH, iMg and normalized magnesium (nMg, normalized or adjusted concentration of iMg to pH 7.40) from 28 inpatients were measured at intervals of 3 min after exposing the samples to air at room temperature. Serum from 30 inpatients was stored in closed tubes at 4°C and −20°C and iMg and nMg levels were measured after 2 days. It was found that serum iMg and nMg concentrations exposed to air were decreased by 0.0023 mmol/l and 0.0001 mmol/l per minute, respectively. nMg did not display any significant changes compared with iMg at 0 min, whereas iMg showed significant changes, which exceeded between‐day precision. For the stored serum, only iMg of serum at −20°C showed no statistically significant changes (p = 0.169). It is concluded that to report the result as iMg, the sample should be kept anaerobically, and if exposed to air, the result should be reported as nMg. For storage, iMg of serum kept anaerobically at −20°C is reliable.

Serum ionized magnesium levels and ionized calcium‐to‐magnesium ratios in adult patients with sickle cell anemia

Low levels of total magnesium in sickle cell erythrocytes have been linked to increased sickling due to cell dehydration. We tested the null hypothesis that adult sickle cell anemia (SCA) patients have the same serum level of ionized Mg (Mg(2+)) and Ca(2+)/Mg(2+) ratio as healthy African Americans (AA) and healthy Caucasians (CAUC). We measured serum Mg(2+) and ionized calcium (Ca(2+)) with ion-selective electrodes and calculated the serum Ca(2+)/Mg(2+) ratios in patients with SCA and control groups (AA and CAUC). Seventy-four SCA patients and 61 controls were compared. SCA patients had significantly (P < 0.001) lower levels of serum Mg(2+) (0.52 +/- 0.05) compared to healthy AA (0.57 +/- 0.04) and CAUC (0.62 +/- 0.03). Eighty-six percent of the adult SCA patients had serum Mg(2+) levels below the mean for the AA group, and 96% of SCA patients were above the AA group's mean serum Ca(2+)/Mg(2+). Of the SCA patients studied, 25.6% (95% CI, 16.2-37.2%) had serum Mg(2+) levels below the racially adjusted lower limit of normal and 50% (95% CI, 38.1-61.9%) were above the upper limit of serum Ca(2+)/Mg(2+) for AA controls. By measuring serum Mg(2+) and Ca(2+), we were able to define a subset of SCA patients with hypomagnesemia and elevated Ca(2+)/Mg(2+) ratios, who may benefit from magnesium supplementation.

Association between the use of antenatal magnesium sulfate in preterm labor and adverse health outcomes in infants

Objective: The purpose of this study was to determine whether the use of antenatal magnesium sulfate prevents adverse outcomes (neonatal intraventricular hemorrhage, periventricular leucomalacia, death, and cerebral palsy). Study Design: In a controlled trial, we randomized mothers in preterm labor to magnesium sulfate, “other” tocolytic, or placebo. At delivery, umbilical cord blood was collected for the later determination of serum ionized magnesium levels. Neonatal cranial ultrasound scans were obtained periodically for the diagnosis of intraventricular hemorrhage and periventricular leucomalacia. Among survivors, the diagnosis of cerebral palsy was made at age 18 months. Results: Children with adverse outcomes had higher umbilical cord magnesium levels at delivery. In regression models that controlled for confounders, which included very low birth weight, magnesium remained a significant risk factor (adjusted odds ratio, 3.7; 95% CI, 1.1-11.9; P =.03). Conclusion: Contrary to original hypotheses, this randomized trial found that the use of antenatal magnesium sulfate was associated with worse, not better, perinatal outcome in a dose-response fashion. (Am J Obstet Gynecol 2002;186:1111-8.)

Association between maternal serum ionized magnesium levels at delivery and neonatal intraventricular hemorrhage

Objectives: To determine whether magnesium sulfate (MgSO4) exposure is associated with a reduced risk for neonatal intraventricular hemorrhage (IVH). Study design: In a randomized, controlled trial, women in preterm labor were randomly assigned to receive MgSO4, “other” tocolytic, or saline control. At delivery, we collected maternal antecubital and umbilical cord blood for determination of serum ionized magnesium levels. Neonatal IVH was diagnosed by cranial ultrasonogram. Results: Among 144 infants, 24 were diagnosed with IVH. Using crude intention-to-treat analysis, we found that 18% (13/74) of survivors exposed after birth to MgSO4 had IVH compared with 16% (11/70) of babies who were not exposed. Infants who had IVH were more likely to have been delivered by mothers with higher serum ionized magnesium (Mg) levels (0.75 vs 0.56 mmol/L) (P =.01). Using multivariable logistic regression, we confirmed that higher Mg levels are a significant predictor of neonatal IVH (adjusted odds ratio, 15.8; 95% CI, 1.4-175.0) even when adjusted for birth weight, gestational age, antenatal hemorrhage, and neonatal glucocorticoid exposure. Conclusions: In mothers with preterm labor, our data indicate that antenatal MgSO4 exposure may be associated with an increased risk for IVH among their newborns. (J Pediatr 2002;140:540-6)

Umbilical Cord Serum Ionized Magnesium Level and Total Pediatric Mortality

Umbilical Cord Serum Ionized Magnesium Level and Total Pediatric Mortality

Umbilical cord serum ionized magnesium level and total pediatric mortality

Objective: To estimate whether higher magnesium levels in umbilical cord blood at delivery are associated with increased total pediatric (fetal + neonatal + postneonatal) mortality. Methods: During the Magnesium and Neurologic Endpoints Trial, in addition to randomizing mothers having preterm labor into arms containing magnesium sulfate, other tocolytic agents, or saline controls, we obtained biologic specimens at delivery, including umbilical cord venous blood on which was determined the serum ionized magnesium level using the AVL 988-4 analyzer (Graz, Austria). Laboratory results were then matched with the pediatric mortalities. The study power was based on the anticipated reductions in neonatal intraventricular hemorrhage related to magnesium usage from 18.9% to 4.4%. For α = .05, 1− β ( power)=80%, two tailed, the total number of infants needed would be 140. Results: Of 149 mothers who gave permission for randomization, ionized magnesium levels were available for 82 children. Seven deaths occurred (one immediately before delivery, three as neonates, and three in the postneonatal period). The median level of ionized magnesium among the seven dead children was 0.76 mmol/L; among the 75 survivors, the median level of ionized magnesium was 0.55 mmol/L (Mann-Whitney U test, P = .03). Using multivariable logistic regression analysis, the association remained statistically significant when controlling for possible confounding factors (adjusted odds ratio 7.7, 95% confidence interval 1.2, 47.6, P = .03). Conclusion: These findings of a dose response between serum ionized magnesium and deaths in children increase our concern about the improper use of tocolytic magnesium.

Serum Ionized Magnesium Levels in Type 2 Diabetic Patients with Microalbuminuria or Clinical Proteinuria

Background/Aims: The association between microalbuminuria and magnesium depletion is a controversial issue, and serum ionized magnesium levels have not been previously studied in patients with different grades of diabetic nephropathy. Therefore, the aim of this study was to evaluate circulating ionized magnesium concentrations in patients with non-insulin-dependent diabetes mellitus (NIDDM) and incipient or overt diabetic nephropathy. Methods: We measured fasting plasma glucose, creatinine, creatinine clearance estimate, total cholesterol and triglycerides, and serum ionized magnesium (ion-selective electrodes, ISE) in 30 NIDDM patients with urinary albumin excretion rate (UAER) <20 μg/min (normoalbuminuria), 30 NIDDM patients with microalbuminuria (20 < UAER < 200 μg/min), 30 NIDDM patients with clinical proteinuria (UAER >200 μg/min), and 20 healthy subjects. Results: Serum ionized magnesium levels were significantly reduced in diabetic patients when compared to control subjects (0.39 ± 0.06 vs. 0.58 ± 0.05 mmol/l, p < 0.001). Moreover, diabetic patients with microalbuminuria or clinical proteinuria showed a significant decrease in serum ionized magnesium with respect to normoalbuminuria group (normoalbuminuria: 0.45 ± 0.02 mmol/l; microalbuminuria: 0.36 ± 0.05 mmol/l, p < 0.001; clinical proteinuria: 0.35 ± 0.04 mmol/l, p < 0.001). Serum ionized magnesium showed a significant negative correlation with plasma HbA1c and triglycerides in both microalbuminuria and clinical proteinuria groups. Multiple linear regression analysis showed that circulating ionized magnesium levels decrease together with the increase of plasma HbA1c and triglycerides in NIDDM patients with incipient or overt nephropathy, also after adjusting for age, sex, BMI, diabetes duration, systolic and diastolic blood pressure, hypoglycemic therapy, plasma creatinine, creatinine clearance, plasma cholesterol and fasting glucose. Conclusions: Microalbuminuria and clinical proteinuria, as well as poor glycometabolic control and hypertriglyceridemia, are associated to relevant alterations in magnesium metabolism, and the measurement of serum ionized magnesium seems to represent a useful biochemical tool for the study of magnesium disturbances in patients with different grades of diabetic nephropathy.

Serum Ionized Magnesium in Premature and Term Infants

Magnesium is the element with the second highest concentration in the body and is found almost entirely in the intracellular compartment. The small serum component gives a poor representation of the active, physiologic state of the metal. This state is assessed much better by measuring ionized magnesium in the serum, which can now be performed with a sensitive ion-selective electrode. This study was undertaken to establish the normal serum ionized magnesium levels in newborn infants and to define normal serum ionized calcium/ionized magnesium ratios. Ninety-seven infants were investigated. Six were born before 32 weeks gestation, 28 between 33 and 37 weeks gestation, and 63 were term. Ionized magnesium levels were 0.69 ± 0.14 mmol/L, 0.63 ± 0.10 mmol/L, and 0.57 ± 0.07 mmol/L in each group, respectively. These findings demonstrate a significant decline in serum ionized magnesium with increasing maturity. This decrease may relate to a greater need for magnesium uptake during earlier gestation, more magnesium-induced vasodilation to maintain adequate blood flow to developing tissues and organs, or immature parathormone function earlier in pregnancy. The progressive rise in serum ionized calcium/ionized magnesium ratios found herein supports the latter hypothesis.

Intravenous magnesium sulphate relieves migraine attacks in patients with low serum ionized magnesium levels: a pilot study.

1. We tested the hypothesis that patients with an acute attack of migraine headache and low serum levels (< 0.54 mmol/l) of ionized magnesium are more likely to respond to an intravenous infusion of magnesium sulphate (MgSO4) than patients with higher serum ionized magnesium levels. 2. Serum ionized magnesium levels were drawn immediately before infusion of 1 g of MgSO4 in 40 consecutive patients with an acute migraine headache. 3. Pain reduction of 50% or more as measured on a headache intensity verbal scale of 1 to 10, occurred within 15 min of infusion in 35 patients. In 21 patients, at least this degree of improvement or complete relief persisted for 24h or more. Pain relief lasted at least 24h in 18 of 21 patients (86%) with serum ionized magnesium levels below 0.54 mmol/l, and in 3 of 19 patients (16%) with ionized magnesium levels at or above 0.54 mmol/l (P < 0.001). Mean ionized magnesium levels in patients with relief lasting for at least 24h were significantly lower than in patients with no relief or brief relief (P < 0.01). 4. Measurement of serum ionized magnesium levels may be useful in identifying patients with migraine headaches who may respond to an intravenous infusion of MgSO4.

Intravenous magnesium sulfate relieves cluster headaches in patients with low serum ionized magnesium levels.

Patients with cluster headaches have been reported to have low serum ionized magnesium levels. We examined the possibility that patients with cluster headaches and low ionized magnesium levels may respond to an intravenous infusion of magnesium sulfate. Thirty-eight infusions of magnesium sulfate were given to 22 patients with cluster headaches. The mean ionized magnesium level prior to 23 infusions which provided relief for at least 2 days and enabled the patient to skip two or more attacks, was 0.521 +/- 0.016 mmol/L; this value was 0.561 +/- 0.016 prior to 15 infusions which were ineffective. These latter 15 infusions were preceded by higher total magnesium levels. The ionized magnesium level prior to the 23 effective infusions was below 0.54 mmol/L in 19 patients. Five of the 15 ineffective infusions were accompanied by basal ionized magnesium levels below 0.54 mmol/L. In 76% of the infusions, there was a correlation between a response and an ionized magnesium level below 0.54 mmol/L. Nine patients (41%) obtained clinically meaningful improvement. Spontaneous remissions and a placebo effect might have accounted for some of the improvement. However, this should have applied equally to all patients, regardless of the ionized magnesium level. Measurements of ionized magnesium may prove useful in elucidating the pathogenesis of cluster headache and in identifying patients who may benefit from treatment with magnesium.

Serum ionized magnesium levels during intravenous MGSO4 therapy of preeclamptic women.

Using a novel ion-selective electrode, we have shown that there is over a 100% increase in venous serum levels of ionized Mg during intravenous MgSO4 therapy of preeclamptic patients. By 6 hours of therapy, the range is 0.92-1.65 mmol/l (95% C.I.). There are strong correlations between levels of ionized and total Mg throughout therapy (r = 0.92-0.95, p < 0.01).

Serum ionized magnesium levels decrease with gestational age in normal pregnant women

193 SERUM IONIZED MAGNESIUM LEVELS DECREASE WITH GESTATIONAL AGE IN NORMAL PREGNANT WOMEN. ~ , J.E. Whitty, B.A. Mason, S.M. Irtenkauf*, D.B. Cotton. Department of Ob/Gya, Hutzel Hospital, Wayne State University. OBJECTIVE: Longitudinal changes in serum ionized magnesium. (IMg) and total magnesium (TMg) during pregnancy have not been adequately described. The aim of the present study was to determine levels of IMg, TMg, ionized calcium (ICa), sodium (NA), potassium (K) and pH values over the course of pregnancy in normal pregnant women. STUDY DESIGN: We obtained venous serum samples from 27 normal pregnant women during their first, second and third trimesters. Gestational ages ranged from 6-37 weeks. Samples were analyzed for IMg, TMg, ICa, Na, K and pH using a biomedical stat profile chemistry analyzer with specific ion sensitive electrodes. Data were analyzed with repeated measures ANOVA. RESULTS: In normal pregnant patients, beth serum IMg and TMg decreased linearly with increasing gestational age (p TERB > RITO. CONCLUSION: Similar K~ values and receptor responses support the use of mononuclear leukocytes as a model for I~adrenoreceptors in less accessible myometrium. (Supported by the ETSU Research Development Committee).