renal-exam 1-magnesium

nature's psysiological calcium blocker, reguates k and ca channels, req for proper functioning of na-k-atpase pump, mg plays a role in the secretion of and bone sensitivity to PTH

antidysrhythmic(DOC for torsades, dig induced tachyarr), seizure prevention and control in toxemia of pregnancy, tocolytic for preterm labor, may be benificial in lowering bp, may improve survival after MI, may improve cardiac fxn and survival in CHF pts

320mg/d

420 mg/d

2nd most abundant INTRAcellular cation after potassium, no hormonal regulation of distribution, often hypo and hyper states found

1.7-2.3 mg/dL

only 30-40% absorbed from ileum and jej, amt absorbed inverse with amt stored and ingested, dependent on vit D for absorption

GFR<30ml/min in renal insufficiency-renal impairment and elderly

mg containing lax and antacids (MOM, Mg citrate), and tx of toxemia of pregnancy and use of ureteral irrigants

neuromuscular blockade, decreased DTRs about 7, somnolence, coma-9, respiratory depression...respiratory arrest >12

hypotension >3, bradycardia >4, complete heart block or asystole >14-15

reduce intake, enhance elim, and antago physiologic effects of Mg, 1. calcium gluconate (chloride) 1 gm IV, directly antag the neuromuscular and CV effects, effects are rapid but short lived, doses can be repeated hourly prn,2. IV saline at 100-150 ml/hr + furosemide 40-80 mg IV q 2-6 hr 3. dialysis if ESRD

hourly Mg in pts with severe, symptomatic hypermg until no sx, Mg <4, then as needed; EKG, urine output, volume status

decreased intake(malnut, alcoholism) decreased abs secondary to bowel disease (IBD, short bowel syn) increased losses (diarrhea/lax/vomiting, prolonged NG suction

renal tubular disorders(interfere with ability to reabsor Mg) hypercalcemia/hypercalciuria(ca and Mg compete for reabs in loop)

diuretics(esp loops), AGs, AMp B, laxative abuse, cisp, cyclos, tacro, dig, foscarnet, pentamidine

glucose, aa, insulin administration to pts with severe malnutritin, acute pancreatitis

neuromuscular hyperactivity: muscle twitching, muscle weakness, tremors, tetany, muscle weakness, paresthesias, chvostcks and trousseau's signs, seizures

ECG changes: QT prolongation, QRS widening, torsades, V fib, coronary artery spasms

hypokalemia, hypocalc(via decreased release or sensitivty of bone to PTH)

resolution of signs/sx, restore normal serum Mg level, correct concommitant elyte abnor, identify and correct underlying cause

Use LBW (or ABW if less than IBW) to calc replacement dose, reduce doses by 50% if CrCl <30 ml/min, replace mg deficit over 3-5 days

available as Mg sulfate 50% solution (1gm/2mL) (1gm=8mEq), dilute to conc NMT 20% to minimize phlebitis, give slow IV (less than or equal to 8mEq/hr, 1 g/hr, to minimize ADRs)

undiluted, very painful, reserved for severe hypomg and no IV access

diarrhea is self-limiting SE, oral converted to Mg-chloride in gut (req acid pH) preparations available as chloride salt may be better tolerated as less is needed, Mg Ox(oxide) 400 mg 1-2 QID, Slow-Mag(chloride) 64 mg 1-2 BID

Day 1: LD-2 gm Mg sulfate mixed with 6 ml NS (for a total of 10 cc) and give IV over 5 min Followed by: 1 mEq/kg IV inf over 24 hours

Day 2-5: 0.5 meq/kg/day in main IV fluids

Monitor: serum Mg hourly until stable q6-12, q24 h

Day 1:1mEq/Kg/24 hours in main IV or divide into 5 doses and give IM q 4 hours

Days 2-5: 0.5 mEq/kg/day in IV main fluids or divide and give IM q 6-8 hours

Monitoring: serum mg q 6-12 hours until stable then q 24 hours

• MOM 5 mL QID
• Mg containing antacides 15 ml TID-QID
• Mg oxide 400 mg 1-2 QID
• Mg chloride 1-2 ts BID

Monitor: serum Mg daily PRN

1-2 gm (LD) over 5 min followed by 0.5-1 gm/hr

10-20 gm IV/24 hours