HIPOMAGNESEMIA.pptx

hipomagnesemia

1. HYPOMAGNESEMIA

2. unit of measurement and NORMAL RANGE Since the molecular weight of magnesium is 24.3 and the valence is +2 , so 1 mEq /L is equivalent to 0.50 mmol /L and to 1.2 mg/ dL mmol /L = [mg/ dL x 10] ÷ mol wt mEq /L = mmol /L x valence Normal range of the plasma magnesium concentration 1.4 to 1.7 mEq /L ~ 0.70 to 0.85 mmol /L ~ 1.7 to 2.1 mg/ dL Yu A S L, et al. 2019. Regulation of Magnesium Balance. UpToDate

3. cut off value for hypomagnesemia Hypomagnesemia is defined as a serum magnesium level <1.7 mg/ dL (<0.71 mmol /L or <1.4 mEq /L) Mild hypomagnesemia (∼1.4–1.7 mg/ dL or ∼ 0.58–0.71 mmol /L or ∼1.16–1.40 mEq /L) Moderate hypomagnesemia (∼1.0–1.4 mg/ dL or ∼ 0.41–0.58 mmol /L or ∼ 0.82–1.16 mEq /L) Severe hypomagnesemia (<1.0 mg/ dL or <0.41 mmol /L or <0.82 mEq /L). Grober Uwe, et al. 2015. Magnesium in Prevention and Therapy. Nutrients 7(9), 8199-8226 Rudolph E H, et al. 2012. Nephrology Secret Chapter 80: Disorders of magnesium metabolism. Mosby, pp 560-570. According to many magnesium researchers, the appropriate lower reference limit of the serum magnesium concentration should be 0.85 mmol /L , especially for patients with diabetes NHANES I identified the reference interval for serum magnesium as 0.75 mmol /L to 0.955 mmol /L with a mean concentration of 0.85 mmol /L.

4. When should hypomagnesemia be corrected ? All authors reviewed agree that hypomagnesemia must be corrected (level of evidence IV, grade of recommendation D). Magnesium repletion should be administered based on the severity of the clinical manifestations and the degree of hypomagnesemia ( Hypomagnesemic patients usually do not develop symptoms until serum Mg falls below 1.2 mg/ dL ) Asymptomatic patients should be treated with oral Mg supplements whenever feasible, whereas severe hypomagnesemia (Mg < 1 mg/ dL ) warrants treatment with parenteral Mg Serum Mg is a poor predictor of total body Mg content because only 0.3% of total body Mg is found in serum. A combination of serum, urinary, and dietary Mg may the most practical method to assess Mg status at present. Yu A S L. 2020. Hypomagnesemia: Evaluation and Treatment. UpToDate ; Penas RD, et al. 2014. SEOM guidelines on hydroelectrolytic disorders. Clin Transl Oncol . 16(12): 1051–1059

5. Yu A S L. 2020. Hypomagnesemia: Evaluation and Treatment. UpToDate ; Karosanidze , Parrish CR, et al. 2014. Magnesium – So Underappreciated. Practical Gastroenterology. NORMOMAGNESEMIC- Magnesium Depletion ?

6. How urgent should we administer additional magnesium? Magnesium repletion should be administered based on the severity of the clinical manifestations and the degree of hypomagnesemia In the acute setting, hemodynamically unstable patients (including those with arrhythmias consistent with torsade de pointes or hypomagnesemic -hypokalemia ) should receive initial IV magnesium over 2 – 15 minutes In hemodynamically stable patients with severe symptomatic hypomagnesemia (such as those with tetany, arrhythmias, or seizures ), Mg concentration ≤ 1 mg/ dL [0.4 mmol /L or 0.8 mEq /L]), IV magnesium can be given initially over 5 to 60 minutes followed by an infusion Yu A S L. 2020. Hypomagnesemia: Evaluation and Treatment. UpToDate ; Berul C I. 2020. Acquired long QT syndrome: Clinical manifestations, diagnosis, and management. UpToDate . In patient with VF/pulseless VT cardiac arrest associated with TdP , Mg infusion occurs over 1 – 2 minutes; In patients without cardiac arrest , infusion should occur over 15 minutes. Magnesium is not likely to be effective in terminating irregular/polymorphic VT in patients with a normal QT interval .

7. Torsa de Pointes (cardiac arrest) & Severe Symptomatic TdP (unstable patient)  2 gram IV bolus MgSO 4 ( 4 mL of 50% solution mixed with D5W to total volume of 10 mL ) The rate of Mg infusion depends on the clinical situation. In patients with pulseless cardiac arrest, infusion occurs over 1 to 2 minutes . If ineffective, may repeat immediately In patients without cardiac arrest, infusion should occur over 15 minutes , as rapid infusion is associated with hypotension and asystole. If ineffective, may repeat dose up to a total of 4 g in 1 hour , followed by infusion . Patient with stable hemodynamic and severe symptomatic hypomagnesemia  1 to 2 grams of MgSO 4 (8 to 16 mEq [4 to 8 mmol ]) in 50 to 100 mL of D5W over 5 to 60 minutes , followed by an infusion. A simple infusion regimen for non-emergent repletion is 4 to 8 g MgSO 4 (32 to 64 mEq [16 to 32 mmol ]) given slowly over 12 to 24 hours (this dose can be repeated as necessary). In the normomagnesemic - hypocalcemia , it has been suggested to repeat this dose daily for 3-5 days . Yu A S L. 2020. Hypomagnesemia: Evaluation and Treatment. UpToDate ; Berul C I. 2020. Acquired long QT syndrome: Clinical manifestations, diagnosis, and management. UpToDate .

8. Stable Asymptomatic Hypomagnesemic Patient Yu A S L. 2020. Hypomagnesemia: Evaluation and Treatment. UpToDate ; Hansen B A., et al. 2018. Hypomagnesemia in critically ill patient. Journal of Intensive Care 6:21 Intravenous repletion in stable hospitalized patients Severe hypomagnesemia  4 to 8 grams of MgSO 4 over 12-24 hours Moderate hypomagnesemia  2 to 4 grams of MgSO 4 over 4 to 12 hours. Mild hypomagnesemia  1 to 2 grams over 1 to 2 hours. Patients with no or minimal symptoms  If available and tolerable, oral replacement Patients with kidney function impairment ( CrCl < 30 mL/min/1.73 m )  at risk for severe hypermagnesemia if large doses of magnesium are given  Reduce the IV Mg dose in such patients by 50% or more and closely monitoring Mg concentrations

9. Maximum Speed and Concentration that can be given thru peripheral vein ? Magnesium sulphate has a high osmolarity and may cause tissue damage if it extravasates into the surrounding tissue. Magnesium sulphate injection is available as 10, 20, 40 and 50% preparations Solutions for IV infusion (peripheral vein) must be diluted to a concentration of 20% or less prior to administration. At concentrations ≥ 20% should be given via CVC. Maximum IV infusion rates should not exceed 2 g/h. When giving IV push , must dilute first and should generally NOT faster than 150 mg/minute . Rapid Mg administration can cause flushing, muscle weakness, or hypotension ; simultaneous volume resuscitation may be advisable. Ayuk J., et al. 2014. Contemporary view of the clinical relevance of magnesium homeostasis. Ann Clin Biochem . Beed M, Sherman R, Mahajann R. 2013. Emergencies in critical care 2 nd edition. United Kingdom: Oxford University Press

10. 1 fl MgSO4 40% = 25 mL 40%  40 gram in 100 mL  4 gram in 10 mL  10 gram in 25 mL 2 gram (5mL) MgSO4 40% + 15 mL D5w  less than 20% 2 grams (5ml) MgSO4 40% + 15 ml 0.9% NaCl  less than 20% 2 gram (5 mL) MgSO4 40% + 5 mL D5w  20% 1 fl MgSO4 20% = 25 mL 20%  20 gram in 100 mL  2 gram in 10 mL  5 gram in 25 mL 2 grams (10ml) MgSO4 20% + 10cc D5w  less than 20% Solutions for IV infusion (peripheral vein) must be diluted to a concentration of 20% or less prior to administration. At concentrations ≥ 20% should be given via CVC

11. IM ADMINISTRATION IM administration is also possible, but is painful and should be reserved as a last resort for patients with no IV access . IM administration of the undiluted 50% solution results in therapeutic serum concentrations in 60 min. 1 – 2 grams of magnesium sulphate ( 2–4 mL of the 50% solution ) can be injected every 6 h for 24 h (4 doses in total) IM. Ayuk J., et al. 2014. Contemporary view of the clinical relevance of magnesium homeostasis. Ann Clin Biochem .