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 mEq/L Toxicity with levels as low as –Lethargy, confusion, tremor, ataxia, muscle jerking or rigidity –Agitated delirium, coma, convulsions –Symptoms may persist for days to weeks

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

#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

#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: 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+

#5: It can Mess with the Anion Gap Na + Cl - HCO 3 - Anion Gap (10 mmol/L)

#5: It can Mess with the Anion Gap Na + Cl - HCO 3 - Anion Gap (4 mmol/L) Li +

#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

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

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

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

#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?

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?

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

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?

#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

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 > mEq/L –Chronic intoxication with level > 4 and Sx