Difference Between Aldosterone and ADH

Aldosterone Vs ADH

The human body is a very complex and intricate system. A simple imbalance can cause grave health effects. Similarly, when the body is experiencing imbalances in fluid volume or significant drops in blood pressure (BP), it tries to compensate by employing several mechanisms to regain its original balance. Ando so, the two very important hormones namely: aldosterone and ADH (anti-diuretic hormone) come into play.

Also known as AVP (arginine vasopressin) or vasopressin per se, ADH conserves body fluids by increasing water reabsorption specifically at the distant convoluted tubules of the nephrons (the basic unit of the kidneys). In addition, it can also trigger retention of urea which further absorbs water back into the system by means of osmosis. This process enables water to travel from two differing areas of concentration (from lower to higher areas of concentration).

On the other hand, aldosterone still triggers the distant convoluted tubules and also the collecting ducts of the kidneys. Thus, it helps reabsorb more water by first reabsorbing sodium. As observed, salt is water-loving. Thus where there is salt, there is also water!

The process of retaining sodium in the body is a more complex pathway because potassium has to be exchanged so as to retain sodium. As more potassium is excreted from the system, the more sodium (and therefore water) will be conserved. In connection to its water conserving properties, aldosterone has a major role to play in the rennin-angiotensin mechanism (RAM). The RAM is a very important biological process that helps regulate one’s blood pressure.

The reason why the hormones ADH and aldosterone are so important in regulating BP is because an increase in the fluid volume in the body also increases the blood pressure. However, in the event that the BP is already too high then the secretion of ADH and aldosterone stops and the other hormone known as the ANP or atrial natriuretic peptide causes excretion of excess fluids and sodium by increasing the glomerular filtration rate (GFR) of the kidneys.

With respect to where ADH and aldosterone are made, the former is made at the hypothalamus. However, its actual hormone release originates from the posterior part of the pituitary gland. The latter is made at the adrenal cortex, which is the adrenal gland’s outer covering.

Overall, although ADH and aldosterone share the same end result of limiting urine output and increasing water reabsorption so as to increase BP and improve the body’s hydration status, they still differ in the following aspects:

1. ADH is made in the hypothalamus whereas aldosterone (like other steroidal hormones) is created by the adrenal cortex.
2. ADH preserves water in a more direct manner while aldosterone preserves water in a more indirect way by first retaining sodium.

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