Composed of 9 chief glands, the endocrine system controls many of the body’s regulatory functions via hormones that act as chemical messengers. The endocrine system interacts with body organs and tissues, serving as a major contributor to overall health and wellness. Endocrine disorders are numerous and often affect multiple body systems due to abnormally high or low levels of specific hormones. Endocrine diseases are grouped according to the involved gland.

Thyroid Diseases

The thyroid hormones affect virtually every tissue in the body, controlling metabolic rate and aiding in the regulation of numerous other vital functions. Hypothyroidism describes inadequate production of these hormones, resulting in slow metabolism. Common symptoms include fatigue, feeling cold, weight gain, constipation and dry skin. The opposite situation occurs with hyperthyroidism. Overproduction of the thyroid hormones amps up body metabolism, causing symptoms such as feeling overheated, nervousness, weight loss, diarrhea and difficulty sleeping. Thyroid enlargement can occur with hypothyroidism or hyperthyroidism.

Pancreas and Parathyroid Disorders

Diabetes mellitus is a multifaceted, complicated disorder. The primary forms are type 1 and type 2. The disease is caused by an inability to produce or utilize the blood-sugar-lowering hormone insulin, which is made in the pancreas. Possible signs and symptoms of diabetes include high blood and urine sugar levels, frequent urination, blurred vision, disorientation and tingling sensations.

Parathyroid hormones regulate blood calcium levels. If abnormally low, hypoparathyroidism results with low blood calcium. Possible signs and symptoms of this rare condition include muscle weakness, spasms, nervous system agitation and dense bones. Hyperparathyroidism involves high parathyroid hormone and calcium levels. Signs and symptoms might include impaired memory, poor concentration, muscle aches, weakness, abdominal pain, digestive upset and fragile bones.

Pituitary and Hypothalamus Disorders

Multiple hormones originate in the pituitary gland, and their release is controlled by the adjacent endocrine gland called the hypothalamus. Many of the hormones produced by the pituitary regulate the function of other endocrine glands, such as a thyroid, adrenals and the gonads. Some examples of pituitary hormones and associated diseases include: -- Antidiuretic hormone, or ADH, governs body fluid levels. Diabetes insipidus occurs when ADH production is impaired, causing increased urination and continual thirst. -- Growth hormone, or GH, controls healthy growth in children. Giantism and acromegaly occurs when too much GH is produced, resulting in bone overgrowth. In pituitary growth failure, GH levels are too low, leading to stunted and delayed growth. -- Thyroid stimulating hormone, or TSH, promotes thyroid hormone production. Reduced TSH from the pituitary leads to hypothyroidism, and abnormally high TSH causes hyperthyroidism, despite no malfunction in the thyroid gland itself.

Adrenal Diseases

The adrenal gland makes hormones called corticosteroids, which regulate cellular and glucose metabolism, and body levels of charged particles called electrolytes. When corticosteroids are overproduced, Cushing syndrome occurs with manifestations such as thin extremities, increased abdominal and upper back fat, weakness and high blood pressure. Addison disease happens with insufficient corticosteroid production. Signs and symptoms may include fatigue, weakness, low blood sugar, low blood pressure and increased skin pigmentation.

The adrenals also produce androgens, sex hormones similar to testosterone. Overproduction leads to a condition called adrenal virilism. Signs and symptoms are usually more obvious in women and might include increased body hair, acne, deepening of the voice, hair loss, increased muscularity and menstrual irregularities. Men may experience infertility.

Pineal, Ovarian and Testicular Disorders

The pineal gland produces melatonin, the hormone responsible for daily rhythms and sleep. Seasonal affective disorder, or SAD, is associated with low melatonin production. Symptoms of this disorder, which results from decreased sunlight exposure during late autumn and winter, include depressed mood plus disturbed sleeping patterns and eating habits.

The testes in men and ovaries in women produce sex hormones essential for reproduction and, in females, pregnancy, childbirth and lactation. Too little sex hormone production from the ovaries or testes often indicates a problem with the pituitary and/or hypothalamus, as these glands regulate gonad function. Imbalanced sex hormone production can also occur with thyroid disorders and other diseases.