Diuretics are a method for reducing blood pressure. There are different kinds and work in different ways. They have other uses as well. This article is part of a series on hypertension based on lectures given by myself.
Diuretics reduce blood volume
Diuretics function in one way or another on the kidney and associated networks to increase the amount of fluid being excreted by the kidney. This leads to total fluid volume reduction which can have several beneficial effects on various medical problems. Examples of conditions that can benefit from volume reduction include:
– Hypertension, where less circulating blood volume means lower blood pressure.
– Congestive heart failure – where fluid overload is caused by the inability of the heart to push enough blood forward.
– Nephrotic syndrome – where the fluid is retained in the body due to loss of albumin.
Different kinds of diuretics
Diuretics are divided into groups and classes based on their effects, the locus upon which they function, and their particular chemical properties. In classic hypertensive medicine, diuretics are divided by how they affect potassium. Some diuretics may reduce blood pressure by mechanisms other than simple volume reduction. When referring to the volume reduction effect of diuretics the cardiac mechanism which leads to reduced blood pressure is termed “preload”.
Potassium wasting diuretics – Loop diuretics (Furosemide, lasix, fusid), Disothiazide
Potassium-sparing diuretics – Spironolactone, ACE inhibitors
Others – Dopamine
Potential side effects of diuretics
Diuretics have certain potential side effects that may limit their use.
-As a rule, volume reduction can lead to overly low blood pressures and dehydration. This can be unhealthy and may be associated with fainting, headaches as well as difficulty rising from sitting to standing – termed orthostatic hypotension.
– Diuretics override compensatory mechanisms of the kidney designed to conserve vital electrolytes. The use of diuretics can cause a variety of electrolyte disturbances such as disturbances in sodium, potassium, or calcium. The disturbance can be either an elevated level or a decreased level depending on the particular diuretic.