Diuretics

• Diuretics increase urine output. This is related to the amount of sodium and chloride that is blocked from being reabsorbed. They are used to treat hypertension and to mobilize edematous fluid
• The kidneys role is to take waste out of the blood and conserve essential substances
• Three types of diuretics

  • loop diuretics
  • thiazide diuretics
  • potassium sparing diuretics
• The highest percentage of reabsorption is in the proximal tubule
• Loop diuretics block the reabsorption of sodium and chloride in the ascending loop of Henle (thick loop). This prevents water from being reabsorbed and increases urine production
• Loop diuretics act on stroke volume in the BP equation. By reducing circulating fluid, you reduce blood volume which reduces stroke volume. This decreases BP
• Furosemide is a loop diuretic. Its therapeutic response is improving the edema in feet, legs or sacral area. It increases urine output and decreases BP and calcium levels
• Adverse effects of loop diuretics:

  • hyponatremia
  • hypochloremia
  • dehydration
  • hypotension
  • hypokalemia
  • ototoxicity
  • hyperuricemia (too much uric acid)
• Interactions of loop diuretics

  • ototoxic drugs
  • potassium sparing diuretics
  • antihypertensive agents
  • NSAID (decreased blood flow to kidneys results in less diuretics traveling to the kidneys)
• Thiazide diuretics block the reabsorption of sodium and chloride in the early segment of the distal convoluted tubule. It prevents water from being reabsorbed and increases urine production
• Thiazide diuretics are less effective than loop diuretics since there is a smaller percentage of sodium and chloride reabsorption in the DCT
• Hydrochlorothiazide and chlorothiazide are thiazide diuretics. Metolazone is a thiazide like diuretic
• Thiazide diuretics have the same adverse effects as loop diuretics except the risk of ototoxicity
• Thiazide diuretic interactions

  • potassium sparing diuretics
  • antihypertensive agents
  • NSAIDs
• Potassium sparing diuretics block the reabsorption of sodium and promote the retention of K+. It occurs in the late DCT and collecting duct.
• Potassium sparing diuretics

  • prevents water from being reabsorbed
  • modest increase in urine production
  • some of the diuretics block aldosterone receptors
  • retain potassium which can be used to counteract the potassium loss caused by thiazide and loop diuretics
• Spironolactone is a potassium sparing diuretic. It acts very slowly so cannot be used for pulmonary edema. Its therapeutic response is the improvement in edema in the feet, legs and sacral area
• Potassium sparing diuretics interactions

  • thiazide and loop diuretics: counter potassium sparing effects and lower BP if needed
  • agents that increase potassium levels: potassium supplements, salt substitutes, ACE inhibitors (block sodium potassium pump)
• Diuretic nursing implications

  • monitor vital signs (especially BP)
  • instruct patients to take meds in the morning to minimize nocturia
  • monitor fluid volume status (intake and output) and serum electrolytes
  • instruct patients to weigh themselves daily
  • teach patients to eat more potassium rich foods when taking potassium wasting diuretics