The kidneys and adrenal glands are intimately related, both in terms of location and certain functions. However, patients with kidney disease or adrenal disorders often focus upon one organ at the expense of the other. Knowing more about both organs provides a more holistic view that helps patients take better care of themselves.
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Just as humans have two kidneys, they also have two adrenal glands. The adrenals are orange triangular tissues about 2 inches long, sitting on top of the fist-sized kidneys. Taken together, the kidneys and adrenals appear like one contiguous organ, even though they perform very different functions.
The kidneys play an important role in the circulatory and excretory systems.
As part of the circulatory system, kidney structures include renal arteries and other blood vessels. As part of the excretory system, kidneys are involved in removing wastes from the blood. This is a very different process than removing wastes from the digestive system.
The adrenal glands are part of the endocrine system. The endocrine system includes a set of glands throughout the body that produces hormones.
Hormones produced by the adrenals include glucocorticoids such as cortisol, mineral corticoids such as aldosterone, and androgens such as testosterone, adrenalin and norepinephrine. Taken together, these hormones are involved in regulating blood pressure, the stress response and the inflammatory response. Since the amount of testosterone made by the adrenals is very small compared to the testes, this does not have a significant impact on male sexuality.
The adrenals and kidneys also work together to regulate blood pressure. The kidneys make renin, which is a chemical messenger to the adrenals. The renin put out by the kidneys signals the adrenals to make three hormones: angiotensin I, angiotensin II and aldosterone. These hormones regulate fluid volumes, vascular tension and sodium levels, all of which affect blood pressure.
Many kidney patients take prednisone to minimize the amount of protein spilled into the urine by the kidneys. Prednisone also has a powerful effect on the adrenal glands.
Prednisone acts as a corticosteroid, just like the ones produced by the adrenals. When patients take prednisone, the adrenals cease producing corticosteroids. When patients stop taking prednisone, they gradually taper the dosage down to give the adrenal glands the opportunity to "wake up" and start producing corticosteroids again.