What are the contraindications for different types of diuretics, such as loop (e.g. furosemide) (Lasix), thiazide (e.g. hydrochlorothiazide) (HCTZ), and potassium-sparing (e.g. spironolactone) (Aldactone) diuretics?

Diuretics: Types and Contraindications

Loop diuretics, thiazide diuretics, and potassium-sparing diuretics each have specific contraindications that must be considered before prescribing to avoid serious adverse effects and complications.

Loop Diuretics (e.g., Furosemide/Lasix)

Contraindications:

• Anuria 1
• Hypersensitivity to furosemide 1
• Severe electrolyte depletion
• Concomitant use with certain ototoxic drugs (increased risk of ototoxicity)

Precautions:

• Renal impairment (requires monitoring)
• Hepatic cirrhosis with ascites (risk of electrolyte imbalance)
• Diabetes mellitus (may worsen glucose control)
• Gout (increases uric acid levels)
• Sulfonamide allergy (cross-sensitivity possible)

Thiazide Diuretics (e.g., Hydrochlorothiazide/HCTZ)

Contraindications:

• Anuria 2
• Hypersensitivity to thiazides or sulfonamide-derived drugs 2
• Severe renal impairment (GFR <30 mL/min) 3

Precautions:

• History of gout (increases uric acid levels)
• Diabetes mellitus (impairs glucose tolerance)
• Hypercalcemia (reduces calcium excretion)
• Hyponatremia (risk of worsening)
• Systemic lupus erythematosus (may exacerbate or activate)

Potassium-Sparing Diuretics (e.g., Spironolactone/Aldactone)

Contraindications:

• Hyperkalemia 4
• Addison's disease 4
• Concomitant use of eplerenone 4
• Severe renal impairment (GFR <30 mL/min) 3
• Anuria

Specific for Spironolactone:

• Pregnancy (risk of feminization of male fetus)
• Significant renal dysfunction 3
• Concomitant use with other potassium-sparing agents 3
• Concomitant use with potassium supplements 3

General Considerations for All Diuretics

Electrolyte Monitoring:

• All patients treated with diuretics should have electrolytes monitored shortly after initiating therapy and periodically thereafter 3
• Potassium levels require close monitoring, especially when combining different diuretic classes

Drug Interactions:

• Avoid NSAIDs with diuretics (may reduce efficacy and worsen renal function) 3
• ACE inhibitors or ARBs with potassium-sparing diuretics can cause severe hyperkalemia 3
• Loop diuretics may interact with aminoglycosides (increased ototoxicity risk) 5
• Lithium toxicity risk increases with diuretic use 5

Special Populations

Elderly:

• Higher risk of orthostatic hypotension
• Delayed elimination of potassium-sparing diuretics 3
• Increased risk of electrolyte disturbances
• May require lower initial doses

Liver Disease:

• Potassium-sparing diuretics are preferred in patients with liver cirrhosis and ascites 3
• Careful monitoring of electrolytes and renal function required

Heart Failure:

• Loop diuretics are preferred in patients with symptomatic heart failure 3
• Aldosterone antagonists (spironolactone/eplerenone) are beneficial in advanced heart failure (NYHA III-IV) 3

Adverse Effects to Monitor

• Hypokalemia with loop and thiazide diuretics 6
• Hyperkalemia with potassium-sparing diuretics 3
• Volume depletion and prerenal azotemia 7
• Metabolic alkalosis (loop and thiazide diuretics) 7
• Metabolic acidosis (carbonic anhydrase inhibitors) 7
• Glucose intolerance (particularly with thiazides) 8
• Hyperlipidemia (transient with thiazides) 8
• Hyperuricemia and gout exacerbation 6
• Ototoxicity (with high-dose loop diuretics) 6

Algorithm for Diuretic Selection

1. Assess renal function:

   • GFR <30 mL/min: Consider loop diuretics
   • GFR >30 mL/min: Either loop or thiazide diuretics appropriate

2. Consider comorbidities:

   • Heart failure: Loop diuretics preferred
   • Hypertension: Thiazides often first-line
   • Liver cirrhosis: Consider aldosterone antagonists
   • Diabetes: Monitor glucose closely with thiazides

3. Check baseline electrolytes:

   • Hyperkalemia: Avoid potassium-sparing diuretics
   • Hypokalemia: Consider potassium-sparing diuretics or combination therapy

4. Review medication list for interactions:

   • ACE inhibitors/ARBs: Use potassium-sparing diuretics cautiously
   • NSAIDs: Avoid if possible or monitor closely
   • Digoxin: Monitor potassium levels carefully

5. Start with lowest effective dose and titrate as needed

Remember that diuretic therapy should be individualized based on the specific clinical situation, with careful attention to contraindications and potential adverse effects.