How should an adult patient on lithium with suspected lithium toxicity, presenting with tremor, confusion, renal impairment and polyuria, be treated and what fluid resuscitation protocol should be used?

Treatment and Fluid Resuscitation for Lithium Toxicity

In an adult patient with suspected lithium toxicity presenting with tremor, confusion, renal impairment, and polyuria, immediately discontinue lithium, initiate aggressive intravenous fluid resuscitation with 0.9% normal saline at 15-20 ml/kg/h (1-1.5 liters in the first hour), and urgently arrange hemodialysis if serum lithium is ≥3.5 mEq/L with significant symptoms or if there is cardiovascular compromise regardless of level. 1, 2

Immediate Management Steps

Discontinue Lithium and Assess Severity

• Stop lithium immediately upon suspicion of toxicity 2
• Obtain STAT serum lithium level, complete metabolic panel including electrolytes, BUN, creatinine, and calculate GFR 1, 3
• Obtain ECG to evaluate for arrhythmias (bradycardia, AV block, QT prolongation) 1
• Assess cardiovascular status for hypotension and arrhythmias, which are common acute complications 1
• Evaluate mental status changes (confusion indicates moderate-to-severe toxicity) 1

Fluid Resuscitation Protocol

Initial aggressive fluid resuscitation is critical because lithium toxicity is often precipitated by dehydration, and the patient's polyuria and renal impairment indicate volume depletion 1, 4:

• Start with 0.9% normal saline (isotonic saline) at 15-20 ml/kg/h during the first hour (approximately 1-1.5 liters in an average adult) 5

• This aggressive initial rate addresses the intravascular volume depletion and helps restore renal perfusion 5

• After the first hour, adjust fluid rate to 4-14 ml/kg/h based on:

  • Corrected serum sodium (if normal or elevated, may switch to 0.45% NaCl; if low, continue 0.9% NaCl) 5
  • Hemodynamic response (blood pressure improvement) 5
  • Urine output monitoring (requires bladder catheterization) 5
  • Cardiac and renal status to avoid fluid overload 5

• Monitor for signs of fluid overload, particularly given the renal impairment: assess for pulmonary edema, measure input/output carefully, and perform frequent clinical examination 5

• Avoid potassium-containing fluids (such as Lactated Ringer's or Hartmann's solution) as lithium toxicity can cause hyperkalemia 5

Electrolyte Management

• Once renal function is confirmed and serum potassium is known, add 20-30 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO4) if hypokalemia is present 5
• Correct electrolyte imbalances, particularly potassium and magnesium, as these are essential for managing potential arrhythmias 1
• Monitor serum osmolality and ensure the induced change does not exceed 3 mOsm/kg/h to prevent complications 5

Hemodialysis Indications

Hemodialysis is the definitive treatment for severe lithium toxicity and should be arranged urgently in the following situations 1, 2:

• Serum lithium ≥3.5 mEq/L with significant neurological or cardiovascular symptoms 1
• Any lithium level with significant cardiovascular compromise (symptomatic bradycardia, advanced AV block, refractory hypotension) 1
• Serum lithium ≥4.0 mEq/L regardless of symptoms 6
• Refractory toxicity despite conservative management 1
• Acute renal failure complicating lithium toxicity (as in this patient with renal impairment) 7, 8

Hemodialysis Protocol

• Use high-flux hemodialysis membranes with bicarbonate dialysate for optimal lithium removal 9
• Continue dialysis until lithium level <1.0 mEq/L is achieved after redistribution 1
• Duration typically 6-8 hours, with measurement 4-6 hours post-dialysis to evaluate for rebound 1
• Be prepared for rebound elevations in serum lithium as intracellular lithium equilibrates with extracellular fluid; consecutive hemodialysis sessions may be required 7, 9
• High-flux membranes remove lithium more efficiently than conventional dialysis and reduce the risk of rebound toxicity 9

Management of Specific Complications

Cardiovascular Complications

• For arrhythmias: Correct electrolytes (potassium, magnesium) as primary treatment 1
• Avoid antiarrhythmic drugs that prolong QT interval (amiodarone, sotalol) if QT prolongation is present 1
• For refractory hypotension: Use IV fluids first, then vasopressors (norepinephrine) if needed, with urgent hemodialysis if hypotension persists 1

Renal Complications

• The patient's renal impairment may be due to:
  • Direct tubular epithelial damage from lithium 7, 8
  • Volume depletion (often rapidly reversible with fluid resuscitation and dialysis) 9
• Acute renal failure in lithium toxicity is often reversible with aggressive treatment 7, 9

Nephrogenic Diabetes Insipidus

• The polyuria indicates lithium-induced nephrogenic diabetes insipidus (NDI), which occurs in up to 40% of patients 10
• This concentrating defect increases dehydration risk and contributed to the current toxicity 6, 10
• NDI will improve after lithium discontinuation, though recovery may take weeks 10

Important Caveats

• Do NOT use activated charcoal – it does not bind lithium and is ineffective 4
• Do NOT use mannitol – it is potentially nephrotoxic and offers little benefit over crystalloid resuscitation alone 5
• Avoid NSAIDs – they increase lithium levels and worsen toxicity 1, 4
• Monitor for rebound toxicity after initial improvement, as lithium redistributes from intracellular stores 7, 9
• Assess for precipitating factors: dehydration, medication interactions (NSAIDs, ACE inhibitors, diuretics), intercurrent illness 1

Monitoring During Treatment

• Serum lithium levels every 4-6 hours initially, then after each dialysis session 1, 9
• Continuous cardiac monitoring for arrhythmias 1
• Hourly urine output via bladder catheter 5
• Serial electrolytes, BUN, creatinine every 4-6 hours 1
• Frequent neurological assessments for mental status changes 5
• Hemodynamic monitoring (blood pressure, heart rate) 5