Endocrine Flashcards
What is the range for normal serum TSH levels?
0.4-6.15 u/ml
What is the endocrine system composed of?
The endocrine system is composed of the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreatic islets, ovaries, and testes.
What 4 categories are hormones classified into?
1) Amines and Amino acids (epinephrine, norepinephrine & Thyroid hormones)
2) Peptides, Polypeptides, Proteins and Glycoproteins (Thyrotropin releasing hormone, follicle stimulating hormone & growth hormone)
3) Steroids (corticosteroids - produced in adrenal cortex)
4) Fatty Acid derivatives (retinoids)
Explain paracrine action.
Paracrine action refers to a type of cell signaling where a cell releases chemical messengers (hormones or signaling molecules) that act on neighboring or nearby target cells rather than traveling through the bloodstream to distant sites.
Explain autocrine action.
Autocrine action refers to a type of cell signaling where a cell releases chemical messengers (hormones or signaling molecules) that act on the same cell that produced them. - the cell responds to its own signal.
Which gland plays an important role in regulating the endocrine system.
The pituitary gland.
What is the primary role of the pituitary gland?
To secrete hormones into the blood stream.
The disorders of the endocrine gland are manifested as __________ & ____________
Hyper & Hypofunction
What is acromegaly?
Progressive enlargement of peripheral body parts resulting from excessive secretion of growth hormone
Acromegaly is often caused by a pituitary adenoma.
Define Addison’s disease.
Chronic adrenocortical insufficiency due to inadequate adrenal cortex function
It can lead to fatigue, weight loss, and low blood pressure.
What characterizes an Addisonian crisis?
Acute adrenocortical insufficiency; characterized by hypotension, cyanosis, fever, nausea/vomiting, and signs of shock
This is a medical emergency requiring immediate treatment.
What is adrenalectomy?
Surgical removal of one or both adrenal glands
It may be performed to treat tumors or conditions affecting adrenal function.
What is adrenocorticotropic hormone (ACTH)?
Hormone secreted by the anterior pituitary, essential for growth and development
ACTH stimulates the adrenal cortex to produce cortisol.
What are androgens?
Male sex hormones
Examples include testosterone and dehydroepiandrosterone (DHEA).
What does basal metabolic rate refer to?
Chemical reactions occurring when the body is at rest
It is a measure of energy expenditure in a neutrally temperate environment.
What is calcitonin?
Hormone secreted by the thyroid gland; participates in calcium regulation
It helps lower blood calcium levels by inhibiting osteoclast activity.
Describe Chvostek sign.
Spasm of the facial muscles produced by sharply tapping over the facial nerve; suggestive of latent tetany in patients with hypocalcemia
It indicates neuromuscular excitability due to low calcium levels.
What are corticosteroids?
Hormones produced by the adrenal cortex or their synthetic equivalents
They are used to treat inflammation and autoimmune conditions.
What is Cushing’s syndrome?
Group of symptoms produced by an oversecretion of adrenocorticotropic hormone; characterized by truncal obesity, “moon face,” acne, abdominal striae, and hypertension
It can result from a tumor or prolonged use of corticosteroids.
Define diabetes insipidus.
Condition in which abnormally large volumes of dilute urine are excreted as a result of deficient production of vasopressin
It leads to excessive thirst and frequent urination.
What does euthyroid mean?
State of normal thyroid hormone production
This indicates that the thyroid gland is functioning properly.
What is exophthalmos?
Abnormal protrusion of one or both eyeballs
It is commonly associated with Graves’ disease.
What are glucocorticoids?
Steroid hormones secreted by the adrenal cortex in response to ACTH; produce a rise of liver glycogen and blood glucose
Cortisol is the primary glucocorticoid.
Define goiter.
Enlargement of the thyroid gland
It can result from iodine deficiency or autoimmune diseases.
What is Graves disease?
A form of hyperthyroidism; characterized by a diffuse goiter and exophthalmos
It is an autoimmune disorder where the immune system stimulates the thyroid.
What are hormones?
Chemical transmitter substances produced in one organ or part of the body and carried by the bloodstream to other cells or organs
They have specific regulatory effects on various bodily functions.
What are mineralocorticoids?
Steroid hormones secreted by the adrenal cortex
They are involved in the regulation of sodium and potassium balance.
Define myxedema.
Severe hypothyroidism; can be with or without coma
It presents with symptoms such as swelling, weight gain, and sensitivity to cold.
What is negative feedback?
Regulating mechanism in which an increase or decrease in the level of a substance decreases or increases the function of the organ producing the substance
This mechanism helps maintain homeostasis.
What is pheochromocytoma?
Adrenal medulla tumor
It can cause episodes of hypertension, palpitations, and sweating.
What does SIADH stand for?
Syndrome of inappropriate antidiuretic hormone
It involves excessive secretion of antidiuretic hormone despite low serum osmolality levels.
What is thyroidectomy?
Surgical removal of all or part of the thyroid gland
It is performed to treat conditions such as thyroid cancer or hyperthyroidism.
Define thyroiditis.
Inflammation of the thyroid gland; may lead to chronic hypothyroidism or may resolve spontaneously
Various types include Hashimoto’s thyroiditis and subacute thyroiditis.
What is thyroid-stimulating hormone (TSH)?
Released from the pituitary gland; causes stimulation of the thyroid, resulting in release of T3 and T4
TSH levels are used to assess thyroid function.
What is a thyroid storm?
Life-threatening condition of the thyroid due to untreated hyperthyroidism
It can cause fever, tachycardia, and altered mental status.
What is thyrotoxicosis?
Condition produced by excessive endogenous or exogenous thyroid hormone
It can lead to symptoms such as weight loss, anxiety, and heat intolerance.
What is thyroxine (T4)?
Thyroid hormone; active iodine compound formed and stored in the thyroid
T4 is converted to the more active T3 in peripheral tissues.
What is triiodothyronine (T3)?
Thyroid hormone; formed and stored in the thyroid; released in smaller quantities, biologically more active, and with faster onset of action than T4
T3 has widespread effects on cellular metabolism.
Describe Trousseau sign.
Carpopedal spasm induced when blood flow to the arm is occluded; suggestive sign for latent tetany in hypocalcemia
It indicates neuromuscular irritability due to low calcium levels.
What is vasopressin?
Antidiuretic hormone secreted by the posterior pituitary
It helps regulate water balance in the body.
When diagnosing a patient with an endocrine disorder, what information from their health history is important to obtain?
Patients should be asked if they have experienced changes in the following areas: energy level, tolerance to heat or cold, weight, thirst, frequency of urination, bowel function, body proportions, muscle mass, fat and fluid distribution, secondary sexual characteristics (e.g., loss or growth of hair), menstrual cycle, memory, concentration, sleep patterns, mood, vision, joint pain, and sexual dysfunction.
When diagnosing a patient with an endocrine disorder, what physical assessment should be done?
Physical, psychological, and behavioral changes should be noted. Examples of changes in physical characteristics on examination may include appearance of facial hair in women, “moon face,” “buffalo hump,” exophthalmos (abnormal protrusion of one or both eyeballs), vision changes, edema, thinning of the skin, obesity of the trunk, thinness of the extremities, increased size of the feet and hands, edema, and hypo- or hyperreflexia. The patient may also exhibit changes in mood and behavior such as nervousness, lethargy, and fatigue.
In terms of assessing for endocrine dysfunctions, why do we do blood tests?
Blood tests determine the levels of circulating hormones, the presence of autoantibodies, and the effect of a specific hormone on other substances (e.g., the effect of insulin on blood glucose levels). The serum levels of a specific hormone may provide information to determine the presence of hypo- or hyperfunction of the endocrine system and the site of dysfunction.
In terms of assessing for endocrine dysfunctions, why do we do urine tests?
Urine tests are used to measure the amount of hormones or the end products of hormones excreted by the kidneys.
Why would we do a 24 hr urine specimen?
A 24-hour urine specimen is collected to measure hormone levels and their metabolites over a full day, providing a more accurate assessment of endocrine function compared to a single blood test.
What are stimulations tests used for, how does it work?
Stimulation tests are used to confirm hypofunction of an endocrine organ. The tests determine how an endocrine gland responds to the administration of stimulating hormones that are normally produced or released by the hypothalamus or pituitary gland. If the endocrine gland responds to this stimulation, the specific disorder may be in the hypothalamus or pituitary. Failure of the endocrine gland to respond to this stimulation helps identify the problem as being in the endocrine gland itself.
Explain suppression tests, how does it work?
Suppression tests are used to detect hyperfunction of an endocrine organ. They determine if the organ is not responding to the negative feedback mechanisms that normally control secretion of hormones from the hypothalamus or pituitary gland. Suppression tests measure the effect of a given exogenous dose of the hormone on the endogenous secretion of the hormone or on the secretion of stimulation hormones from the hypothalamus or pituitary gland.
Which hormones does the posterior pituitary gland secrete?
ADH (Vasopressin)
Oxytocin
Which hormones does the anterior pituitary gland secrete?
Growth Hormone
ACTH
Thyroid Stimulating Hormone (TSH)
FSH & LH
Prolactin
What controls the Pituitary gland?
The Hypothalamus.
What are the main functions of the hormones TSH, ACTH, FSH and LH?
The main function of TSH, ACTH, FSH, and LH is the release of hormones from other endocrine glands
What is an imbalance in Adrenocorticotropic Hormone (ACTH) secretion characterized by?
Imbalanced ACTH secretion characterizes both Addison’s disease (hypoproduction) and Cushing’s syndrome (hyperproduction).
What does ADH/Vasopressin control?
the excretion of water by the kidney; its secretion is stimulated by an increase in the osmolality of the blood or by a decrease in blood pressure.
What will happen if a total destruction of the pituitary gland occur as a result of a tumor, trauma or vascular lesion?
This will remove all stimuli that are normally received by the thyroid, the gonads, and the adrenal glands. This leads to extreme weight loss, emaciation, atrophy of all endocrine glands and organs, hair loss, impotence, amenorrhea, hypometabolism, and hypoglycemia. Coma and death occur if the missing hormones are not replaced
Explain Diabetes Insipidus.
The most common disorder related to posterior lobe dysfunction is diabetes insipidus (DI), a condition in which abnormally large volumes of dilute urine are excreted as a result of deficient production of vasopressin
What factors may have an effect on the occurrence of DI?
DI may occur following surgical treatment of a brain tumor, secondary to nonsurgical brain tumors, traumatic brain injury, infections of the nervous system, post hypophysectomy (removal of the pituitary), failure of renal tubules to respond to ADH, and the use of specific medications
Almost all pituitary tumors are benign and are _____ _______ .
slow growing
What is the difference between functional pituitary tumors and non-functioning pituitary tumors?
Functional tumors secrete pituitary hormones, whereas nonfunctional tumors do not
Name the principal types of pituitary tumors.
The principal types of pituitary tumors represent an overgrowth of Eosinophilic cells,
Basophilic cells, or Chromophobic cells (i.e., cells with no affinity for either eosinophilic or basophilic stains).
Eosinophilic tumors that develop early in life result in ___________.
Gigantism
How does gigantism developed in adulthood present itself?
If the disorder begins during adult life, the excessive skeletal growth occurs only in the feet, the hands, the superciliary ridge, the molar eminences, the nose, and the chin, giving rise to the clinical picture called acromegaly. However, enlargement involves all tissues and organs of the body, and many of these patients suffer from severe headaches and visual disturbances because the tumors exert pressure on the optic nerves
Basophilic tumors give rise to ____________ .
Cushing’s syndrome
How does Cushing’s syndrome present itself?
Its features largely attributable to hyperadrenalism, including masculinization and amenorrhea in females, truncal obesity, hypertension, osteoporosis, and polycythemia.
Which tumors represent 90% of pituitary tumours?
Chromophobic tumors
How does Chromophobic tumors present themselves?
These tumors usually produce no hormones but destroy the rest of the pituitary gland, causing hypopituitarism.
People with this disease often have obesity, are somnolent, and exhibit fine, scanty hair; dry, soft skin; a pasty complexion; and small bones. They also experience headaches, loss of libido, and visual defects progressing to blindness. Other signs and symptoms include polyuria, polyphagia, a lowering of the basal metabolic rate.
What is the name of the surgery used to remove the pituitary gland?
Hypophysectomy.
Hypophysectomy is the treatment of choice in patients with Cushing’s disease resulting from excessive production of ACTH by a pituitary tumor.
What scans are used to diagnose pituitary tumors?
CT & MRI
What are 4 ways to characterize Diabetes insipidus?
central, nephrogenic, or dipsogenic, as well as gestational
Explain the etiology of nephrogenic DI.
Nephrogenic DI etiologic factors include kidney injury, medications such as lithium, hypokalemia, and hypercalcemia.
Explain the etiology of central DI.
The primary etiology for central DI is head trauma but other causes include surgery, infection, inflammation, brain tumors, or cerebral vascular disease; it also may be idiopathic
Explain the etiology of Dipsogenic DI.
Dipsogenic DI is caused by a defect in the hypothalamus and may be the result of damage to the pituitary gland from a head injury, surgery, infection, inflammatory process, or a tumor
What happens when the kidneys are not receiving ADH?
Without the action of ADH on the distal nephron of the kidney, an enormous daily output (greater than 250 mL per hour) of very dilute urine with a specific gravity of 1.001 to 1.005 occurs. It also contains abnormal substances such as albumin and/or glucose.
Because of the intense thirst, the patient tends to drink 2 to 20 L of fluid daily and craves cold water
True/False
We can treat DI with restriction of fluids. Why/Why not?
FALSE.
The disease cannot be controlled by limiting fluid intake, because the high-volume loss of urine continues even without fluid replacement. Attempts to restrict fluids cause the patient to experience an insatiable craving for fluid and to develop hypernatremia and severe dehydration
What is the fluid depravation test, how is it done?
✔ Fluids are withheld for 8–12 hours or until the patient loses 3%–5% of body weight.
✔ The patient is weighed frequently during the test.
✔ Urine and blood tests (osmolality) are done at the start and end of the test.
✔ If the urine remains dilute (low specific gravity and osmolality) despite dehydration, it indicates Diabetes Insipidus (DI)
How do we treat DI?
The objectives of therapy are to replace ADH (which is usually a long-term therapeutic program), ensure adequate fluid replacement, and identify and correct the underlying intracranial pathology. Nephrogenic causes require different management approaches.
What is the drug of choice for central DI treatment?
Desmopressin, a synthetic vasopressin without the vascular effects of natural ADH, is the drug of choice for central DI. The drug may be given orally or intranasally.
Chlorpropamide and thiazide diuretics are also used in mild forms of the disease because they potentiate the action of vasopressin but are used with caution due to the risk for hypoglycemia.
Can we use Desmopressin to treat nephrogenic DI?
No -Nephrogenic DI occurs due to the kidneys’ resistance to antidiuretic hormone (ADH), not a deficiency of ADH.
If the DI is renal in origin, the previously described treatments are ineffective. Thiazide diuretics, mild salt depletion, and prostaglandin inhibitors (e.g., indomethacin and aspirin) are used to treat the nephrogenic form of DI.
How does the nursing management look like for patients with DI?
- assess for dehydration - Severe dehydration can lead to decreased cardiac output and, therefore, decreased perfusion of the vital organs, specifically the brain and kidneys.
- Ongoing monitoring of vital signs as well as intake and output (I&O) is essential
Explain SIADH and what does it stand for?
The syndrome of inappropriate antidiuretic hormone (SIADH) results from a failure of the negative feedback system that regulates the release and inhibition of ADH. Patients with SIADH cannot excrete a dilute urine, retain fluids, and develop a sodium deficiency known as dilutional hyponatremia.
True/False
SIADH is always and endocrine dysfunction.
False.
SIADH is often of nonendocrine origin; for instance, the syndrome may occur in patients with bronchogenic carcinoma in which malignant lung cells synthesize and release ADH. SIADH has also occurred in patients with severe pneumonia, pneumothorax, and other disorders of the lungs, as well as malignant tumors that affect other organs
What are other reasons for developing SIADH?
Disorders of the central nervous system, such as head injury, brain surgery or tumor, and infection, are thought to produce SIADH by direct stimulation of the pituitary gland. Some medications such as vincristine, phenothiazines, tricyclic antidepressants, thiazide diuretics and nicotine have been implicated in SIAD as they either directly stimulate the pituitary gland or increase the sensitivity of renal tubules to circulating ADH.
How do we medically manage SIADH?
Treatment is focused on eliminating the underlying cause, if possible, and restricting fluid intake. Because retained water is excreted slowly through the kidneys, the extracellular fluid volume contracts and the serum sodium concentration gradually increases toward normal.
Diuretic agents such as furosemide may be used along with fluid restriction. In severe hyponatremia sometimes a hypertonic NaCl (3%) may be prescribed and administered IV
What is the nursing management like for SIADH?
Close monitoring of fluid I&O, daily weight, urine and blood chemistries, and neurologic status is indicated for the patient at risk for SIADH.
