Human adrenal glands exist as a pair of organs situated at the upper pole of the kidneys. Functionally they can be split into two parts: the center, or medulla, secretes adrenaline, while the outer portion, or cortex, makes and releases cortisol and aldosterone. According to the National Adrenal Diseases Foundation, under-activity of the medulla does not result in disease. However, low levels of cortisol and aldosterone can lead to a variety of symptoms.
Low Cortisol
An under-active adrenal gland, also known as Addison's disease, most commonly results in low levels of cortisol. This substance is commonly known as the "stress hormone." According to the National Endocrine and Metabolic Diseases Information Service, decline in cortisol levels is usually gradual, as are the symptoms this decline leads to. Increasing fatigue, muscle weakness, appetite and weight loss all occur, according to the same source. A general state of not feeling well with gastrointestinal symptoms of nausea, vomiting and diarrhea, as well as headache, may occur. Cortisol also lowers blood sugar levels. Depression and mood changes may be seen. The National Adrenal Diseases Foundation website discusses the skin changes that can be associated with under-active adrenal glands. As the body tries to compensate for the lowered hormone levels, another hormone is stimulated that is responsible for skin pigmentation. This stimulation leads to a darkening of the skin that's most notable at skin folds and in wrinkles.
Low Aldosterone
The other hormone of the adrenal cortex is aldosterone. It may or may not be affected by the state of under-active adrenal glands. When the disease is more advanced, low levels of aldosterone can produce symptoms. The National Endocrine and Metabolic Diseases Information Service briefly outlines the function of aldosterone, stating that it regulates salt and water levels in the blood. Therefore, low levels lead to decreased sodium in the blood as well as lowered blood pressure. This decreased blood pressure can be especially noticeable when one stands up and becomes dizzy or light-headed, a condition known as orthostatic hypotension. The diminished sodium levels in the blood can make the patient crave salt in the diet.
Adrenal Crisis
This medical emergency is also known as an Addisonian crisis. It is usually triggered by an acute stress to the system, such as surgery or trauma. Since those with under-active adrenal glands lack the stress hormone cortisol, they are unable to mount an adequate response to the challenge. The Mayo Clinic states that this crisis is characterized by abdominal or back pain, as well as severe vomiting and diarrhea, with resultant dehydration. There is also low blood pressure and the possible loss of consciousness. This condition can be fatal.
