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Ten Things That Really Annoy Me About Lithium

Ten Things That Really Annoy Me About Lithium. Kent R. Olson, MD Medical Director, SF Division California Poison Control System. #10: It Has a Narrow Therapeutic Window, and it can be Nasty. Commonly used for bipolar disorder Therapeutic levels 0.6-1.2 mEq/L

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Ten Things That Really Annoy Me About Lithium

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  1. Ten Things That Really Annoy Me About Lithium Kent R. Olson, MD Medical Director, SF Division California Poison Control System

  2. #10: It Has a Narrow Therapeutic Window, and it can be Nasty • Commonly used for bipolar disorder • Therapeutic levels 0.6-1.2 mEq/L • Toxicity with levels as low as 1.5-2 • Lethargy, confusion, tremor, ataxia, muscle jerking or rigidity • Agitated delirium, coma, convulsions • Symptoms may persist for days to weeks

  3. #9: It Doesn’t Bind to Activated Charcoal • Alternatives: • Emesis, lavage - ? value • Kayexalate? • Whole bowel irrigation: preferred method

  4. #8: It Elevates the White Blood Count • Usually mild, but don’t be surprised to see WBC 15,000 or more • Mostly granulocytes • Enhanced PMN production • Could lead to needless workup for infection

  5. #7: The ECG is Nonspecific • Kinda looks like hypokalemia • T-wave flattening or inversion common • NSSTTW changes common • QT interval may be prolonged • Bradycardia, sinus node arrest - rare

  6. #6: It Can Mess up your Sodium Level • Nephrogenic Diabetes Insipidus • Can occur with therapeutic use • Lack of renal response to ADH • Loss of free water in the urine • Clinical findings: • Volume loss, leads to Li retention • Elevated serum Na+

  7. #5: It can Mess with the Anion Gap Anion Gap (10 mmol/L) Na+ HCO3- Cl-

  8. #5: It can Mess with the Anion Gap Li+ Anion Gap (4 mmol/L) Na+ HCO3- Cl-

  9. #4: Funky Pharmacokinetics • Two-compartment model: Li level reaches equilibrium slowly • Initial: extracellular fluid ~ 15 L • Later: total body water ~ 50 L ~ 4-6 hrs [Li] = 4 [Li] = 1.4

  10. #4: Kinetics, continued . . . • Slowly enters brain cells • Difficult to get it back out • Rebound after hemodialysis

  11. #3: It’s Only Way Out is Through Your Kidneys • Expect toxicity if: • Worsening renal function • Sudden volume depletion (eg, GI flu)

  12. So where are we so far? • Patient with Altered MS • NSSTTW changes • Li Level 4.5 mEq/L • What do we do?

  13. #2: History is Usually Not Available or is Incomplete • Is this an acute OD or chronic use with accidental toxicity? • What is the pre-existing baseline Li? BUN? Cr?

  14. Consider: • Our patient with ALOC, Li 2.5 mEq/L is not on Li routinely, took an acute OD of 14 LiCO3 (8 mEq each) tablets 2 hrs ago • BUN/Cr = 10/1.1 • Is this a serious Li OD?

  15. Or . . . • Our patient is on Li chronically, has been increasingly confused and weak for several days, has had vomiting and diarrhea. • BUN/Cr = 30/2.2

  16. Or, how about this scenario? • A patient was seen to take an acute overdose of Li tablets, is brought to the ED where Li = 9 mEq/L • Is emergency hemodialysis indicated?

  17. #1 Reason Why I Find Lithium Annoying: Dialysis Isn’t So Hot • Acute OD with high Li level: patients do okay anyway, without dialysis • Chronic intoxication with moderate level, altered mental status: it takes days to weeks to recover anyway, despite dialysis

  18. So What Do We DO? • Give IV fluids (NS initially) • Try to get good Hx • Follow Li levels • Consider hemodialysis if • Acute OD with level > 10-11 mEq/L • Chronic intoxication with level > 4 and Sx

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