The Endocrine System is made up of glands that produce and secrete hormones into the bloodstream in an effort to maintain homeostasis. The Glands of the Endocrine Systems can be described as Endocrine, Exocrine or both. Endocrine Glands do not have ducts. They secrete hormones that travel through the bloodstream to their intended target. Glands that have ducts are called Exocrine Glands. These glands use ducts to carry their secretions to a specific location. The hormones produced by the Glands of the Endocrine System may affect one or sometimes many organs. This is accomplished through complex feedback system where some glands release hormones that cause other glands to release or retain hormones. The best way to describe the feedback system of the Endocrine System is to think of it as the air conditioner in your home. We’ll use this analogy as we discuss the functions of the major glands of the Endocrine System.
Let’s start with the hypothalamus. The Hypothalamus is located in the lower part of the brain beneath the thalamus just above the brainstem and secretes hormones that stimulate or suppress the release of hormones by the pituitary gland. The Hypothalamus functions as sort of the controller of the body as necessary by releasing hormones that control the release of other hormones that influence sleep, temperature, hunger, thirst, blood pressure and water balance.
The Pituitary Gland is located just beneath the Hypothalamus and is regarded as “The Master Gland” because it produces and secretes hormones that control the functions of many other glands similar to the way a thermostat in your home controls the release of hot or cold air. The Anterior Pituitary produces and secretes Adrenocorticotropic Hormone (ACTH), Follicle-Stimulating Hormone (FSH), Luteinizing Hormone (LH), Thyroid-Stimulating Hormone (TSH), Prolactin (PRL) and Somatotropin (GH or Growth Hormone). The Posterior Pituitary Gland secretes Antidiuretic Hormone (ADH or vasopressin) as well as Oxytocin (OT). ADH and Oxytocin are actually produced by the Hypothalamus and stored and secreted by the Posterior Pituitary Gland. All of the hormones secreted by the Pituitary Gland are controlled by the Hypothalamus. Think of it this way; At home, if you feel the temperature needs to be adjusted, you adjust the thermostat to control release of hot or cold air. Similarly, the Hypothalamus functions in a similar capacity as you and the Pituitary Gland functions similar to the Thermostat in your home. When the Hypothalamus (You) senses a need to release or retain hormones created by the Thyroid Gland for example, it will release hormones to the Pituitary Gland (the Thermostat) which will in turn releases the Thyroid Stimulating Hormone (TSH) that controls the Thyroid Gland’s production of its hormones. Let’s move on to some other glands of the endocrine system.
The largest endocrine gland is the Thyroid Gland located in anterior side of the neck just below the thyroid cartilage. Like we discussed, the Thyroid Gland produces and secretes hormones when it receives Thyroid-Stimulating Hormone (TSH) from the Pituitary Gland. The major function of the hormones secreted by the Thyroid Gland is to control the metabolic rate of all other glands. Disorders of the Thyroid Gland include HYPOthyroidism which can lead to Myxedema Coma and HYPERthyroidism (or Graves’ Disease) which can lead to a Thyrotoxic Crisis (or Thyroid Storm).
HYPERthyroidism is typically hereditary and is a term used to describe the signs and symptoms associated with an over production of thyroid hormone. Graves’ Disease is a severe form of HYPERthyroidism. There are many signs and symptoms of HYPERthyroidism some of which are; Emotional Changes, Insomnia, Fatigue, Weight Loss or Weight Gain, Palpitations, Intolerance to Heat, Bulging Eyes, Tachycardia and Muscle Weakness. Untreated HYPERthyroidism can result in what is called a Thyrotoxic Crisis or Thyroid Storm. This is a potentially life-threatening condition typically triggered by infection or trauma. Signs and symptoms may include a Change in Consciousness, Confusion, Diarrhea, Pounding Heart, Tachycardia, Shaking, Sweating and Fever. Management includes your ABC as well as treating any symptoms which usually originate from the cardiovascular symptoms.
HYPOthyroidism can be inherited or acquired and is caused by an impairment or non production of the thyroid hormone. This can be the result of the thyroid glands inability to produce thyroid hormone or pituitary dysfunction. Treatment of Graves’ Disease can also result in Hypothyroidism. Hypothyroidism can produce a multitude of signs and symptoms. Some of them are: Fatigue, Lethargy, Weight Gain, “Moon Faced” appearance, Blurred Vision, Intolerance to Cold, Goiter and Bradycardia. If hypothyroidism is not treated, it can lead to HYPOthyroid Myxedema Coma which is a severe and potentially life threatening condition. Myxedema Coma is typically triggered by a secondary event such as Hypothermia, Sepsis, Surgery, Trauma, Stroke or Burns and results in a loss of brain function.
The Parathyroid Gland is located just behind the thyroid gland in the neck and secretes parathyroid hormone (PTH) which helps regulate the calcium levels in the body.
The Thymus Gland is located in the chest between the sternum and the heart. The Thymus Gland produces the white blood cells (T-Lymphocytes) that are part of the immune system and used to fight infections.
The Adrenal Glands are located at the top of each kidney and are made up of the adrenal cortex (the outer portion of the glands) and the adrenal medulla (the inner portion). The Adrenal Cortex produces the steroid hormone such as the glucocorticoids cortisol and corticosterone as well as aldosterone and androgenic hormones such as testosterone and estrogen. The Adrenal Cortex is closely tied to the autonomic nervous systems and controls the body’s salt and water balance (blood pressure), immune system, sexual function and also influences the body’s metabolism. If the Adrenal Cortex produces too much hormone, Hyperadrenalism (commonly known as Cushing’s Disease) may develop. Cushing’s Disease is caused by elevated cortisol levels either because of an too much being produced by the Adrenal Cortex or when too much cortisol is ingested when treating for conditions such as Asthma or COPD. Most cases of Cushing’s Syndrome occur between 25 to 45 years old. The long-term effects elevated levels of Cortisol may lead to Hypertension, Diabetes, Atherosclerosis or Hypokalemia. When Cushing’s Syndrome results in death, it is primarily due to the effects of excess glucocorticoids. A patient suffering from Cushing’s Disease can present with Fatigue, Depression, Visual Disturbances, Headache, they Easily Bruise, and they may have excessive Weight Gain in the face, upper back and torso.
Treatment in the pre-hospital setting should include ABC’s as well as treatment of any additional secondary symptoms such as cardiac or pulmonary compromise.
When the Adrenal Glands do not produce enough cortisol either because of Adrenal dysfunction (referred to as Addison’s Disease) or secondary to injury, an Adrenal Crisis can result. Addison’s Disease is a life-threatening condition that can either be acute or progress over time. Because Cortisol helps regulate glucose, insufficient amounts of cortisol can be deadly. A patient suffering from an adrenal crisis may present with Fatigue, Flank Pain, Low Blood Pressure, Fever, Hyperpigmentation of the skin, Vomiting, Diarrhea, Dehydration, Weight Loss, Altered LOC, Tachycardia, Rapid Respirations (or Tachypnea), Loss of Appetite and/or Abdominal Pain.
In addition to the basic ABC, treatment in the pre-hospital setting should also include close monitoring of both cardiac and pulmonary status, obtain a Blood Glucose level and treat for hypoglycemia if present, establish an IV, provide aggressive fluid resuscitation and rapid transport.
The Inner portion of the Adrenal Glands is the Adrenal Medulla. The Adrenal Medulla produces the catecholamines epinephrine and nor epinephrine which, of course, influence the sympathetic and parasympathetic responses to physical or emotional stress.
The Gonads are the glands that secrete hormones related to sexual function and the reproductive system. In men, the Gonads are the testes. In Women, the Gonads are the ovaries. The Gonads are controlled by Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSA) secreted by the Anterior Pituitary Gland which is, in turn, controlled by the Hypothalamus. The Gonads are both Endocrine and Exocrine glands. Their Exocrine products are sperm and eggs and their Endocrine products in men secrete testosterone and estrogen and the Ovaries in women secrete Estradiol, Progesterone and Inhibin.
The Pineal Gland (or Pineal Body) is located in the center of the brain and secretes the hormone Melatonin at night and Serotonin during the day to regulate sleep.
The Pancreas is located in the upper abdomen just behind the stomach. The Pancreas had both Endocrine and Exocrine functions. The Exocrine function of the Pancreas secretes digestive enzymes into the duodenum through ducts that help digest food. The Endocrine function secretes Insulin and Glucagon directly into the bloodstream. The Alpha cells of the Pancreas secrete Glucagon and the Beta cells secrete Insulin. Together, Insulin and Glucagon regulate the level of glucose in the blood. Insulin is the “key” that glucose needs to enter the cells when glucose is present in circulation. Insulin also stimulates the liver and muscles to store Glucose and Glycogen. Glucagon has the opposite effect on the storage of Glucose in the liver and muscles as Insulin. Glucagon stimulates the liver and muscles to break down and release glycogen if blood sugar levels fall too low. Insulin and Glucagon are constantly working to maintain the proper sugar levels in the body. If the insulin secreting cells do not work properly, diabetes occurs. Under normal conditions, when the food we ingest enters the intestine, the Beta Cells of the Pancreas release Insulin into the blood to aid in the absorption of the incoming glucose, fatty acids and amino acids into the muscles, liver and fat. The stimulation of the Beta Cells also stops the Alpha Cells of the Pancreas from releasing unnecessary Glucagon. This system keeps the sugar levels of the bloodstream from becoming too elevated.
Diabetes Mellitus often referred to as just “Diabetes” occurs when a person has high glucose (or blood sugar) levels either because the Pancreas is not producing any or enough insulin or because the cells in the body do not respond properly to the insulin produced. Remember, Insulin is like a key that allows glucose to enter the cells for energy. When the glucose is not able to enter the cells it accumulates in the bloodstream creating elevated blood sugar levels also known as HYPERglycemia. People with Diabetes are susceptible to numerous complications such as HYPERglycemia, HYPOglycemia, vascular diseases and infections. It is also the leading cause of end stage renal disease, blindness in adults between 20 and 70 years of age as well as amputations of the lower extremities.
Diabetes can is normally diagnosed as either Type I or Type II. Type I Diabetes occurs when the Pancreas does not produce enough Insulin to control blood sugar levels and is typically a life-long condition. Diagnosis of Type I Diabetes typically occurs in childhood or adolescence, but can develop in older adults. The inability of the Pancreas to secrete insulin is most often due to the autoimmune system destroying the Beta cells within the Pancreas. Without insulin, the cells of these patients are unable to utilize glucose although plenty of glucose may be available in the bloodstream. Type I Diabetic patients depend on sources of insulin either by injection or continuous pumps that are administered at various times and relate to such things as food intake and exercise. If the administration of Insulin to these patients is interrupted or stopped blood sugar levels in the bloodstream can elevate to dangerous levels referred to as HYPERglycemia. Untreated Type I Diabetes can lead to Diabetic Ketoacidosis (or DKA) which we’ll discuss in a minute.
Type II Diabetes is often referred to as “Adult Onset” or “NonInsulin-Dependent” Diabetes. This form of Diabetes is most common in adults over the age of 40 where there is a family history of Diabetes. Type II Diabetics are different from Type I in that Type II Diabetics do produce Insulin however, the Insulin they produce is either not enough OR the body does not recognize the Insulin and use it properly. This is called Insulin-Resistance. When there is not enough Insulin produced or the body does not utilize the Insulin, Glucose is unable to enter the cells and the cells are unable to function properly. This results in a build-up of Glucose in the bloodstream (HYPERglycemia) similar to Type I Diabetics. The little bit of Insulin that Type II Diabetics do produce is usually enough to prevent the development of Ketoacidosis. This is why Type II Diabetes is sometimes referred to as “NonInsulin Dependent”. Type II Diabetes accounts for 90% of all Diabetic diagnosis and is generally tied to a family history of Diabetes and/or obesity. Untreated Type I Diabetes can lead to a Diabetic coma known as Hyperglycemic Hyperosmolar Nonketotic Syndrome. We’ll discuss this condition in a minute.
High sugar levels in the blood of Diabetics, over time, can cause damage to nerves, the small blood vessels of the eyes and kidneys leading to blindness and kidney failure as well as damage to the heart through atherosclerosis (or hardening) of the large arteries that can cause heart attack and stroke. In both Type I and Type II Diabetics the body attempts to eliminate the excess sugar through urination. Excessive urination is called Polyuria. This excessive urination leads to dehydration. Symptoms of Diabetes include: Weakness, Weight Loss, Slow-healing sores or frequent infections, and the three P’s; Polydipsia (Excessive Thirst), Polyuria (Excessive Urination) and Polyphagia (Excessive Eating).
As mentioned earlier, untreated Type I Diabetes can lead HYPERglycemia. When blood sugar levels exceed 300, Diabetic Ketoacidosis (or DKA) should be considered. When the cells of the body are unable to utilize Glucose because of the lack of Insulin a change in metabolism occurs and the body begins to break down fat for energy. The byproducts of the fat used are called ketones. These ketones make the blood very acidic otherwise known as acidosis. The high blood sugar level combined with the ketones create a chemical imbalance called Ketoacidosis. This is typically slow onset, anywhere from 12 to 24 hours. The buildup of ketones in the body result in a condition known as HYPERketonemia. Initially, the body may attempt to compensate for the acidosis through the respiratory system. The breathing pattern of DKA patients is often times slow or fast, but deep referred to as Kussmaul’s Respirations. The release of ketones through these respirations is what causes the “Fruity Odor” on their breath. Most commonly, DKA is result of undiagnosed Diabetes or Diabetes that goes untreated. Other causes of DKA include Infection, Injury or Illness. Signs and symptoms of DKA include; Dehydration, nausea, vomiting, Drowsiness, Abdominal Pain, Dry Warm Skin, sometimes HYPOtension, Fruity Oder on their breath, Polydipsea and Polyuria. DKA is rare in Type II Diabetics. Untreated DKA may result in a coma.
When blood sugar levels become severely elevated (above 600), major electrolyte imbalances occur known as Hyperosmolar Hyperglycemia Nonketotic Syndrome or HHNS. Although HHNS can occur in either Type I or Type II Diabetics, HHNS is typically only seen in older, Type II patients. HHNS is characterized by hyperglycemia, hyperosmolarity, and dehydration without significant ketoacidosis because Type II diabetics retain enough pancreatic function to avoid ketones.. Similar to DKA, HHNS is slow onset. In general, any illness or medication that causes dehydration or any drugs that raise glucose levels or inhibit insulin can cause HHNS. HHNS is a life threatening condition with high mortality rate and left untreated, can lead to coma or death.
Signs and symptoms of HHNS are similar to DKA and include; Dehydration, Drowsiness, Dry Warm Skin, Tachycardia, sometimes HYPOtension, Polydipsea and Polyuria. Pre-Hospital treatment of DKA and HHNS should always begin with ABCs followed by Oxygen and treatment of any symptoms which may include cardiac and pulmonary. These HYPERglycemic patients are usually severely dehydrated. Fluid boluses can help rehydrate and dilute the elevated blood sugar levels. Insulin administration is typically done in the hospital setting.
HYPOglycemia is a term for Low Blood Sugar, typically only seen in Diabetic patients. In HYPOglycemia, there is more Insulin in the bloodstream than necessary. This causes an overutilization of Glucose that results in Low Blood Sugar. Because Glucose is the primary source of energy for the brain, HYPOglycemia is a dangerous condition. Similar to a lack of oxygen to the brain, a prolonged lack of Glucose to the brain can result in brain damage or death. In general, Hypoglycemia occurs when blood sugar levels are below 50 although in diabetics, symptoms of HYPOglycemia may present at levels above 50. HYPOglycemia can occur as a result of exercise, missing a meal, alcohol ingestion, some medications or an overdose of Insulin or other Antidiabetic Medications. Patients with kidney failure are also susceptible to HYPOglycemia.
The initial Symptoms of HYPOglycemia are produced in a Sympathetic or Adrenergic Response and may include; Sweating, tremors, anxiety, hunger, dizziness, headache, cloudy vision, confusion and difficulty speaking. As HYPOglycemia progresses and the brain is starved of Glucose, Symptoms can worsen into abnormal behavior, convulsions, seizure, loss of consciousness and coma. HYPOglycemia that results in a loss of consciousness is called Insulin Shock.
Besides the basic ABCs, it is very important to maintain a patent airway and support breathing with plenty of oxygen. Treatment should include attempts to raise the blood sugar level by administering Glucose, Dextrose, Fructose, etc.
Gestational Diabetes is Diabetes that first occurs during pregnancy. In most cases, Gestational Diabetes can be managed by diet and exercise and will typically go away once the baby is born. Expecting mothers with Gestational Diabetes are at higher risk of chronic hypertension and cesarean delivery. If Gestational Diabetes in untreated, it can lead to fetal macrosomia (which is a larger than normal fetus), hypoglycemia or hypocalcemia.
Other forms of diabetes in addition to Type I and Type II are often secondary to another illness and are called Secondary Diabetes. This includes diseases that destroy pancreatic cells such as pancreatitis, cystic fibrosis and pancreatic cancer.
The Kidneys produce two hormones, Erythropoietin (EPO) and Calcitriol as well as the enzyme Renin. Erythropoietin works on bone marrow to increase the production of red blood cells. Stimuli such as bleeding or high altitudes can trigger the release of EPO. Calcitriol promotes the absorption of Calcium in the intestines. Renin is an enzyme that participates in the renin-angiotensin system (or RAS) system responsible for regulating the body’s mean arterial pressure.