Summary

21.1 Review of Endocrine Anatomy and Physiology

• The endocrine system consists of cells, tissues, and organs that secrete hormones critical to homeostasis.
• Endocrine glands are ductless glands that secrete hormones.
• Endocrine communication involves chemical signaling via the release of hormones into the extracellular fluid. From there, hormones diffuse into the bloodstream and may travel to distant body regions, where they elicit a response in target cells. Hormones are chemical substances that travel throughout the body in the bloodstream and affect the activity only of its target cells: that is, cells with receptors for that particular hormone.
• Hormones play a critical role in the regulation of physiological processes because of the target cell responses they regulate. Reflexes triggered by both chemical and neural stimuli control endocrine activity.
• Clinical assessment of the endocrine system is a process that incorporates a patient history, physical examination, and diagnostic testing.
• Endocrine conditions can be nonspecific and varied, and they can affect many body systems.
• Diagnostic testing is targeted based on the findings of a history and physical exam and can include laboratory testing, imaging, and invasive testing.

21.2 Diabetes Mellitus

• Diabetes mellitus (DM) is a disease characterized by inappropriately high blood glucose levels, caused by an imbalance of insulin and glucagon. There are three main types: Type 1 (T1DM), Type 2 (T2DM), and gestational diabetes (GDM).
• T1DM is an autoimmune disease that damages the beta cells of the pancreas so they do not produce insulin; thus, synthetic insulin must be administered by injection or infusion. Risk factors include age, family history, or history of viral infection.
• T2DM occurs when the cells of the body become resistant to the effects of insulin, causing the pancreas to increase its production of insulin. Risk factors include obesity, family history, and inactivity.
• Gestational diabetes (GDM) occurs when beta cells in the pancreas become unable to compensate for the demands of pregnancy, causing a dysfunction in the production of insulin and a reduced insulin sensitivity resulting in high blood glucose levels. Risk factors include obesity, family history, and polycystic ovary syndrome.
• Common symptoms associated with DM are polyuria, increased thirst, unplanned weight loss, increased hunger, blurry vision, tingling or numbness in hands or feet, decrease in energy, dry skin, increased infections, and slow wound healing.
• DM is diagnosed primarily through evaluation of fasting serum glucose levels, hemoglobin A1c levels, or oral glucose tolerance testing (OGTT).
• Patients with DM should be continuously monitored for complications, such as signs of hypoglycemia and hyperglycemia. When a patient with diabetes is experiencing stress or an infection, the nurse should plan to assess their blood glucose levels more frequently. Patients should also be thoroughly educated about their condition.
• Treatment of DM is patient-specific and involves education and patient engagement, medication, lifestyle changes, and glucose monitoring. Patients with T1DM are prescribed insulin. Patients with T2DM and GDM may be prescribed oral antihyperglycemics or insulin based on their individual blood glucose control needs and response to initial treatments.

21.3 Thyroid and Parathyroid Disorders

• Thyroid disorders occur when the thyroid gland releases inappropriate levels of hormones. This creates imbalance in the functions that regulate how the body metabolizes proteins, fats, and carbohydrates, as well as in how efficiently the body uses energy, consumes oxygen, and produces heat.
• Dietary iodine deficiency can result in the impaired ability to synthesize T3 and T4, leading to a variety of severe thyroid disorders.
• Common disorders of the thyroid include hyperthyroidism, hypothyroidism, and thyroid cancer. Because the thyroid controls metabolism, heart rate, and body temperature, clinical signs and symptoms of a thyroid disorder usually involve hyper- or hypo-activity with these functions.
• Parathyroid disorders, such as hyperparathyroidism and hypoparathyroidism, develop when parathyroid glands release inappropriate levels of PTH hormone, which controls calcium levels in the body.
• Clinical manifestations of parathyroid disease are unusual in the early stages. Signs and symptoms vary and are dependent on the type of disorder present, but they usually mimic signs and symptoms of hypercalcemia and hypocalcemia.
• To determine whether a patient has a thyroid or parathyroid disorder, begin with a subjective assessment that asks focused questions to determine if the patient is experiencing any symptoms or has a previous medical history of neck issues. The information gathered from this subjective assessment can then guide a physical assessment.
• Diagnostic testing for thyroid or parathyroid disorders includes bloodwork, imaging, and biopsy. The type of testing depends on what the subjective and objective data reveal.
• Care of the patient with a thyroid or parathyroid disorder involves educating the patient and family, following the plan of care, and monitoring for complications.
• Medical therapies for a thyroid disorder include medications to correct inappropriate levels of thyroid hormone and thyroidectomy. Medical therapies for a parathyroid disorder include removal of the parathyroid and medications to correct electrolyte imbalances and bone density problems.

21.4 Pituitary Disorders

• The pituitary gland is a bean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in response to hypothalamic stimulation.
• Chronic underproduction of antidiuretic hormone (ADH) or a mutation in the ADH receptor results in diabetes insipidus (DI). If the posterior pituitary does not release enough ADH, water cannot be retained by the kidneys and is lost as urine.
• The main clinical manifestations of DI are extreme thirst (polydipsia) and the production of large amounts of urine (polyuria).
• Diagnosis of DI involves confirming polyuria and figuring out the underlying cause. Common tests include a 24-hour urine collection, fluid deprivation test, and hypertonic saline infusion test.
• When caring for patients with DI, it is important to closely monitor intake and output, daily weights, vital signs, changes in level of consciousness, skin turgor, mucus membranes, and laboratory values.
• Treatment strategies for DI include treating the underlying cause and ensuring the patient drinks enough fluids to maintain hydration.
• Unsuppressed or over-release of ADH results in syndrome of inappropriate antidiuretic hormone release (SIADH). The excess ADH prevents the production of urine in the kidneys, impairs water secretion, and leads to hypervolemia and hyponatremia.
• Clinical manifestations of SIADH are usually due to decreased extracellular fluid osmolality and hyponatremia. This causes cerebral edema, and symptoms tend to be neurological.
• Diagnostic testing for SIADH should rule out underlying causes, such as hypothyroidism or adrenal insufficiency. Serum osmolality and serum sodium will both be low. Urine sodium levels will be elevated due to increased free water absorption in the renal collecting tubules.
• In patients with SIADH, it’s important to closely monitor intake and output, daily weights, vital signs, changes in level of consciousness, mental status, and laboratory values. It is also important to assess for Cheyne-Stokes respirations.
• Treatment for SIADH involves treating the underlying condition (such as pulmonary or CNS infection) and preventing any further decrease in sodium levels.

21.5 Adrenal Disorders

• The adrenal glands are wedges of glandular and neuroendocrine tissue adhering to the top of the kidneys by a fibrous capsule. One of their major functions is to respond to stress. Adrenal hormones also have several non–stress-related functions, including the increase of blood sodium and glucose levels.
• Adrenal insufficiency is a primary insufficiency of the adrenal glands from complete or partial destruction of the adrenal cortex. This damage prevents the adrenal glands from producing adequate amounts of cortisol and aldosterone. It also causes low glucose levels, low sodium levels, and high potassium levels.
• Patients with adrenal insufficiency have progressive, nonspecific symptoms that include fatigue, weight loss, generalized weakness, abdominal pain, nausea, vomiting, and dizziness. Hyperpigmentation and vitiligo may be present.
• Diagnosis of adrenal insufficiency is confirmed by low serum cortisol and aldosterone levels, a blunt cortisol response with ACTH stimulation, and an elevated renin activity test.
• Treatment of adrenal insufficiency involves hormonal replacement, which is a lifelong therapy.
• Cushing’s syndrome is a condition in which the body is exposed to too much circulating cortisol over a long period of time. The cause can be exogenous or endogenous.
• Clinical manifestations of Cushing’s syndrome include weight gain, water retention, weakness, fatigue, headache, delayed wound healing, easy bruising, bone pain, loss of height, hirsutism (excess hair growth), impotence, decreased libido, menstrual irregularities, and frequent infections. Additional physical findings may show moon face, buffalo hump, hirsutism, thin extremities, muscle wasting, swollen ankles, purplish striae, skin atrophy, acne, and central obesity.
• A low-dose dexamethasone suppression test is done to confirm Cushing’s syndrome. Imaging may also be completed to rule out cancer or pituitary involvement.
• Nursing care for patients with adrenal disorders is based on the assessment data, with the goals of reducing symptoms and preventing complications. Patient teaching should include information about the disease, testing, treatment, and signs and symptoms to report to the provider.
• Treatment for exogenous Cushing’s disease includes a slow taper off steroid therapy. In endogenous cases, surgery or radiation therapy may be done. If a bilateral adrenalectomy is performed, the patient must be placed on lifelong hormone replacement therapy.