Diuretics

Diuretics are substances that increase the excretion of water and electrolytes via the kidneys. They are both regulated naturally within the body and used deliberately as medicinal substances in order to influence the fluid balance, the blood volume and the blood pressure. Diuretics play an important role in the regulation of the water and electrolyte balance. Characteristic of diuretics is their effect on different sections of the kidney, in particular on the nephrons. Depending on the mechanism of action, they influence the reabsorption of sodium, chloride, potassium or water and thus lead to an increased urine volume. The type of diuretic determines the strength, the duration and the composition of the excretion.

What functions do diuretics fulfill in the body?

  • Increase in water excretion: Diuretics raise urine production and reduce excess fluid.
  • Regulation of the blood volume: Through fluid loss, the circulating blood volume decreases.
  • Influence on the blood pressure: A reduced amount of fluid lowers the blood pressure.
  • Control of the electrolyte balance: Sodium, potassium and chloride levels are influenced.
  • Relief for the heart and circulation: Reduced volume lessens the strain on the heart.
  • Support of kidney function: Filtration and excretion are modulated in a targeted manner.

What types of diuretics are there?

Diuretics can be classified according to their site of action:

  1. Loop diuretics: Act strongly in the ascending part of the loop of Henle.
  2. Thiazide diuretics: Influence the distal tubule.
  3. Potassium-sparing diuretics: Reduce potassium losses during excretion.
  4. Osmotic diuretics: Increase osmotic water excretion.
  5. Hormonally influenced diuresis: Regulated by ADH and aldosterone.

How do diuretics work in the body?

The effect is based on several mechanisms:

  • Inhibition of the reabsorption of sodium
  • Osmotically induced water loss
  • Change in the hormone action in the kidney
  • Influence on the electrolyte distribution

As a result, the urine volume rises and the fluid balance is adjusted.

When do diuretics play a special role?

Fluid overload
  • Edema
  • Fluid accumulations
Blood pressure regulation
  • Hypertension
Hormonal control of the water balance
  • ADH and aldosterone action

Conclusion

Diuretics are important regulators of the water and electrolyte balance and play a central role in the control of fluid volume and blood pressure. Through their targeted effect on the kidneys, they enable a flexible adaptation to different physiological and pathophysiological situations. A balanced regulation of diuresis is decisive for the stability of the internal milieu and for the function of the cardiovascular and renal system.