Endocrinology Test 1
Terms
undefined, object
copy deck
- Name hormones released by the hypothalamus
- - TRH (thyroid-releasing hormone) - GnRH (growth hormone-releasing hormone)
- Name 8 hormones released by the pituitary gland
- - ACTH - Growth hormone - TSH - FSH - LH - Prolactin - Oxytocin - ADH
- What hormones are secreted by the thyroid gland?
- thyroxine (T4) and triiodothyronine (T3)
- What hormones are secreted by the pancreas
- glucagon and insulin
- Name hormones secreted by the adrenal gland
- cortisol, aldosterone, and norepinephrine
- What are the 4 structural groups that categorize hormones?
- 1. Peptides and proteins 2. Steroids 3. Amino Acid derivatives 4. Fatty Acid derivatives
- What type of structural hormone is insulin?
- peptide and protein hormone
- What are 2 types of hormones derived from the amino acid tyrosine?
- - thyroid hormones: a double thyrosine with either 3 or 4 iodine atoms - catecholamines: include epinephrine or norepinephrine are used as hormones and neurotransmitters
- Name 2 other amino acids and the hormones that they synthesize
- 1. Tryptophan - a precursor to serotonin and the pineal hormone melatonin 2. Glutamic acid - a precursor to histamine
- What are eicosanoids?
- a large group of molecules derived from polyunsaturated fatty acids, such as Arachadonic acid
- Name the principal groups of hormones derived from eicosanoids or arachadonic acid?
- - prostaglandins - prostacyclins - leukotrienes - thromboxanes
- What 3 factors determine the concentration of hormones?
- 1. rate of production 2. rate of delivery 3. rate of degradation or elimination
- What organs produce thyroid hormone?
- - thyroid gland - pituitary gland - peripheral muscle
- What are the hormones produced by the alpha and beta cells of the pancreas?
- - alpha cells produce glucagon - beta cells produce insulin
- Explain how control of glucose exhibit positive and negative feedback
- - positive feedback occurs when an increase in blood glucose stimulates the release of insulin - negative feedback occurs when glucose levels fall and the pancreas stops releasing insulin
- What hormones stimulate and inhibit secretion of growth hormone?
- - growth hormone-releasing hormone (GHRH) stimulates secretion of growth hormone - somatostain, released by hypothalamus, inhibits growth hormone
- Name a hormone that is secreted when growth hormone binds to receptors in the liver
- insulin-like growth factor I (IGF-I)
- What disorder is caused by an excess of ACTH secretion?
- Cushing's syndrome
- What are physiologic effects of IGF-1?
- - stimulates proliferation of chondrocytes (cartilage cells), resulting in bone growth - simulates the differentiation and proliferation of myoblasdts - stimulates amino acid uptake and protein synthesis in muscle and other tissues
- What are the most common secretory pituitary tumors?
- prolactinomas
- Deficiency in ADH or insevsitivity of the kidneys to ADH can result in what disease state?
- diabetes insipidus, which is manifested as polyuria and polydispia
- Inappropriate secretion of ADH in excess amounts results in what disease state?
- Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and causes hyponatremia
- What are the 2 general causes of diabetes insipidus?
- 1. Central (or neurogenic) - a failure of the posterior lobe of the pituitary to secrete adequate amounts of ADH 2. Nephrogenic - a failure of the kidney to respond to adequate amounts of circulating ADH
- True/False: Small tumors tend to cause and increase of hormone secretion
- - Small tumors tend to increase hormone production - Large tumors tend to decrease hormone production (tumor becomes space-occupying lesion & compresses and retards hormone production) The correct answer is: True
- Where are the hypothalamic-hypophyseal portal veins located?
- between the capillary beds of the lower hypothalamus and anterior pituitary
- What vessel carries hormones from the pituitary gland to the systemic circulation?
- hypophyseal vein
- What are physical manifestations of a large pituitary tumor?
- - headaches - bitemporal hemianopsia
- What are the major target organs of growth hormone?
- liver and adipose tissue
- What is the effect of growth hormone on insulin activity?
- - growth hormone anti-insulin activity - it supresses the ability of insulin to stimulate uptake of glucose in peripheral tissues - enhances glucose synthesis in the liver - GH also stimulates insulin secretion (leading to hyperinsulinemia)
- What is acromegaly?
- - excessive secretion of growth hormone in adults - causes an overgrowth of bone and connective tissue; leads to coarse features - excessive growth hormone and IGF-1 also leads to metabolic derangements, including glucose intolerance
- What are clinical features of acromegaly?
- - widening of the hands and feet - coarsening of the facial features - frontal sinus enlargement - prominent supra-orbital ridges - mandible frows downward and forward (prognathism)
- How is hypersecretion of GH diagnosed?
- - measure GH levels 2 hours after oral glucose load (normally GH levels should decrease) - if oral glucose test is positive, MRI to localize tumor
- What is the treatment for GH secreting tumor?
- 1. Trans-sphenoidal microsurgery (Tx of choice) 2. Radiotherapy (but it takes too long for onset of effects to occur) 3. Medical Managment - use of dopamine agonist (cabergoline), somatostain analogues (octreotide, lacreotide), GH receptor blockers (Pegvisomant)
- What is the most common secretory pituitary tumor?
- prolactinomas
- What are signs and symptoms of prolactinomas?
- - in men, gynecomastia, loss of libido, impotence, and tumor symptoms (headache, visual impairment - in women, increased bilateral discharge (Galactorrhea), Amenorrhea, infertility, & S/S of decreased estrogen (osteopenia, vaginal dryness, hot flashes, irritability)
- True/False: Micro-prolactinomas are more common in men
- False. Micro-prolactinomas are more common in women. Macro-prolactinomas are more common in men The correct answer is: False
- What prolactin level usually implies prolactinomas?
- > 200 ng/mL
- What are some causes of small elevation in prolactin levels?
- - pregnancy - stress - nipple stimulation - drugs (phenothiazines, methyldopa, cimetadine) - hypothyroidism - chronic renal failure - some chest wall lesions
- What is the treatment for hyperprolactinemia?
- 1. Bromocriptine (dopamine agaonist) causes shrinkage of the tumor and restores gonadal function and fertility 2. Trans-sphenoidal surgery - used when the patient has visual field abnormalities, neurological symptoms, or when the patient cannot tolerate medical treatment
- What is the cause of hyperthyroidism?
- - caused by excess ciruculating T4 or T3 - 90% of cases are caused by Graves disease, toxic multinodular goiter, toxic solitary goiter
- What is the pathophysiological cause of Graves Disease?
- - results from IgG antibodies against the TSH receptor - antibodies are called thyroid-stimulating antibodies (TSAb)
- True/False: Atrial Fib is common in all patients with Graves Disease
- Atrial fib is rare in young patients but occurs in over 50% of male patients over 60 y/o The correct answer is: False
- What are cardinal signs of Graves' disease?
- - Conjunctival edema and ulceration - Diffuse goiter - Exophtalmos - Increased lacrimation - Lid lag (usually on downard eye movement) - Lid retration - Peri-orbital puffiness - Pretibial myxoedema - Tachycardia with a bounding pulse - Vascular bruit can be heard over these goiters
- A 60 y/o patient presents with atrial fib, heart failure, and weight loss. What should the clinician be suspicious of?
- hyperthyroidism
- What are treatment options for hyperthyroidism?
- 1. Anti-thyroid drugs - Carbimazole or methimazole followed by propylthiouracil (PTU) 2. Beta-blocking drugs - for the initial stages of management 3. Sub-total thyroidectomy 4. Radioactive iodine therapy
- What are side-effects of thyroidectomy?
- - hypothyroidism (will have to be on Synthroid) - hypoparathyroidism