Overview of Diuretics
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Diuretics are commonly used medications for a variety of conditions, including hypertension, heart failure, cirrhosis and other conditions. Diuretics can affect electrolyte balance as they interfere with the control of renal function. This is especially true when diuretics are used in combination.

Managing diuretics

It is common for a patient on diuretics to become hypokalaemic. This is dangerous because it predisposes to arrhythmias. It may also precipitate encephalopathy in those with liver failure.
You can reduce the risk by taking potassium chloride supplements, or by taking potassium sparing diuretics. The KCl supplements have to be taken in large quantities, which irritates the stomach.
However, the risk posed by hypokalaemia is often overrated by clinciains, and as such, potassium sparing diuretics and potassium supplements are often given when they are not needed. It is best to give them only in at risk patients.
  • In cases of emergency, IV potassium can be given, but this can lead to fatal hyperkalaemia, and the patients may suffer arrhythmias from this also.
The risk of hypokalaemia is greatest in:
  • Those on thiazide (as opposed to loop) diuretics
  • Those on a high dose of diuretic
  • Those with a co-existing high aldosterone secretion, such as those with cirrhosis or nephrotic syndrome.

Uses of diuretics

  • Oedema in heart failure. Mild oedema can be managed by a thiazide, but more serious disease requires a loop diuretic. A large dose may be needed in renal failure.
  • Nephrotic syndrome
  • Hepatic cirrhosis
  • Hypertension low dose of a thiazide diuretic is often used. Resistant hypertension may require spironolactone or a loop diuretic.


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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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