The adrenals are a pair of triangular glands that sit atop each kidney. Each adrenal has two main tissues: the medulla and the cortex. The medulla secretes two hormones, epinephrine and norepinephrine, which stimulate the body's response to stressful situations. The cortex secretes corticosteroids, which affect the body's metabolism and inflammatory response; androgen steroids, which are sex hormones; and aldosterone, a hormone primarily responsible for the body's salt and fluid balance.
Facts about Mineralocorticoids
Mineralocorticoids are hormones that the body secretes to maintain an adequate fluid and salt balance. Salts are composed of electrolytes like sodium and potassium; these electrolytes affect the body's fluid content. Aldosterone is the main mineralocorticoid hormone, secreted by the adrenal cortex in response to signals from the brain and the kidneys. Aldosterone acts on the kidneys to increase the reabsorption of sodium from the urine being formed within the kidneys, and to increase the excretion of potassium. Cortisol, another hormone released by the adrenal cortex, works mostly in the body's stress response, but has a weak mineralocorticoid effect, and in high enough doses can work like aldosterone.
Aldosterone Deficiency Causes
A deficit in aldosterone hormone can have serious health consequences. According to the National Endocrine and Metabolic Diseases Information Service, destruction of the adrenal cortex or a lack of stimulus to secrete aldosterone can cause this condition, known as adrenal insufficiency. Addison's disease is a condition in which the adrenal cortex is destroyed and unable to produce aldosterone. This is an autoimmune condition, which means that the body destroys the adrenal cortex thinking it is foreign tissue that does not belong. Secondary adrenal insufficiency results from a lack of stimulus from the brain to secrete adrenal hormones.
Effects on Salt and Fluid Balance
Sodium and potassium are electrolytes that control the fluid balance in the body. Since water in the body follows the higher levels of sodium, by retaining this electrolyte, aldosterone also retains water in the body, affecting fluid balance and blood pressure. If the body retains too much sodium and fluid, high blood pressure can result. If the potassium level becomes too low, muscle cramps can occur. Likewise, if the body does not secrete enough aldosterone, sodium can become low, resulting in low blood pressure and brain swelling. High potassium levels can cause dangerous heart rhythms.
Aldosterone Deficiency Symptoms
The symptoms of adrenal insufficiency can be mild at first and, according to the University of Maryland Medical Center, may appear only in stressful situations. Symptoms include weakness, fatigue, dizziness, nausea and vomiting. Muscle aches, lack of appetite and dehydration soon follows. Untreated, patients may suffer an Addisonian crisis, which can lead to kidney failure and shock.
