First Aid Endocrine Flashcards
In addition to congenital cause, name 3 causes of nephrogenic diabetes
MC congenital (mutation in ADH receptor rendering it nonresponsive)
Others
- Lithium toxicity
- hypercalcemia (chronic Ca over 11)
- demeclocycline: abx that reduces responsiveness of collecting tubules to ADH (used in the tx of SIADH)
Key feature to distinguish primary hyperparathyroidism and familial hypocalciureic hypercalcemia
FHH = defect in calcium sensor in the parathyroid glad => PTH levels are normal despite hypercalcemia
In FHH urine calcium is low, while hypercalciuria in primary hyperPTH
What are the anterior vs. posterior pituitary derived from?
Anterior pituitary derived from oral ectoderm (Rathke pouch)
Posterior pituitary derived from neuroectoderm (connected to hypothalamus by neurophysis)
Describe vitamin D’s impact on serum Ca+2 and PO4-3
Vit D increases intestinal absorption of both Ca and phosphorus
Vit D also stimulates bone breakdown => increases both Ca and PO in serum
Desmopressin
(a) What is it
(b) Indication
Desmopressin = ADH analog
(a) Vasopressin/ADH analog
(b) Used to tx diabetes insipidus
How may IgG4 related disease present w/ thyroid manifestation?
Ridel Thyroiditis = chronic thyroiditis that can be a manifestation of IgG4-related systemic disease
Causes normal thyroid tissue to be replaced by fibrous tissue => dense, fixed thyroid gland (painless goiter)
MC hormone deficiency in congenital adrenal hyperplasia
21 hydroxylase
Analogs of what hypothalamic hormone can be used to treat acromegaly
Somatostatin analog b/c somatostatin inhibits GH and TSH secretion
Clinical presentation of glucagonoma
Very high glucagon: 4 D’s
- dermatitis (necrolytic migratory erythema)
- diabetes (hyperglycemia)
- DVT
- depression
MC cause of acromegaly
(a) Serum marker
Acromegaly = effect of elevated growth hormone in adults, MC 2/2 pituitary adenoma
(a) Elevated IGF-1 (insulin growth factor 1) whose release is stimulated by GH
How does pH affect serum calcium levels
(a) Basic or acidic environment cause muscle cramps/paresthesias?
40% of serum calcium exists bound to albumin, pH can change conformation/affinity of albumin
(a) Increased pH (basic) makes albumin more negative (fewer H+ around) => albumin has higher affinity for Ca2+ => less free (unbound) serum calcium => symptoms of hypocalcemia such as muscle pain, cramps, and paresthesias
Name 4 genetic syndromes w/ pheochromocytomas
Pheo found in
- MEN2A
- MEN2B
- von Hippel Lindau (pheo, b/l renal cell carcinoma, retinal and intracranial hemangioblastoma
- NF1
Name the d/o of vit D deficiency in
(a) Children
(b) Adults
Vit D deficiency in
(a) Children = Rickets
(b) Adults = osteomalacia
Which GLUT receptor is insulin sensitive?
(a) Where are they located?
GLUT4 is insulin sensitive
(a) Insulin sensitive tissues = striated muscle, adipocytes, cardiomyocytes
Clinical features of cretinism (congenital hypothyroidism)
Either thyroid agenesis or iodine deficiency =>
Severe MR (poor brain development) Large protruding tongue Protruding umbilicus (ventral hernia)
MC adrenal tumor in
(a) Adults
(b) Children
MC adrenal tumor in
(a) Adults = pheochoromocytoma (nonmalignant tumor of adrenal medulla)
- p/w episodic HTN
(b) Children = neuroblastoma (malignant tumor of neural crest cells anywhere along sympathetic chain)
Presentation of nonfunctional pituitary adenoma
Mass effect => bitemporal hemianopsia (visual field deficits), headache, symptoms of hypopituitarism
Adrenal medulla
(a) Type of cells
(b) Secretory product
(c) Control system
Adrenal medulla
(a) Cromaffin cells
(b) Secrete catecholamines: epi and norepi
(c) Controlled by sympathetic fibers
Function of the posterior pituitary
Posterior pituitary stores ADH and oxytocin produced by hypothalamus
Name the 3 complications of thyroidectomy surgery
Thyroidectomy complications
- Hoarseness 2/2 damage to recurrent larygneal nerve
- Hypocalcemia 2/2 accidental removal of parathryoid glands
- Airway compromise of b/l transection of superior laryngeal nerve
What type of hypersensitivity is Hashimoto’s thyroiditis?
Hashimoto’s thyroidism = combined type II and type IV hypersensitivity reaction
Type II = 2/2 preformed antibodies (anti-TSH receptor antibodies)
Type IV = direct destruction of thyroid tissue by CD8 (cytotoxic killer T cells) and by CD4-attracted macrophages
Waterhouse-Friderichsen
(a) What is it?
(b) Classic cause
(c) Physical exam
Waterhouse-Friderichsens
(a) Acute adrenal insufficiency 2/2 b/l adrenal hemorrhage/infarct
(b) Classically caused by neisseria meningitides septicemia 2/2 endotoxicemia and DIC
(c) Meningitis and petechiae
Tx of DKA
DKA tx
-IV fluids (b/c pt is wildly dehydrated and hyperosmolar)
-IV insulin (need to get that glucose into the cells!! cells are starving)
-give glucose as well b/c the amount of insulin you’ll need to give, need to prevent hypoglycemia
-K+ b/c as you give insulin this will push K+ into cells and pt will get hypokalemic
-
Distinguish MEN1, MEN2A, MEN2A
MEN 1 (3 P’s): parathyroid carcinoma, pancreatic adenoma (gastrinoma => Zollinger-Ellison), pituitary adenoma (prolactinoma)
Is serum CK elevated in hypo or hyperthyroidism?
Hypothyroidism myopathy
-about 80% of pts w/ chronic hypothyroidism have some muscle/weakness complaint
Elevated CK seen in hypothyroidism
DKA
(a) Triggers
(b) Explain where the ketones come from
DKA
(a) Increased insulin requirement in times of stress: such as infection, MI, drugs, also med noncompliance or undiagnosed
(b) Lipolysis reved up to make more substrate, producing ketones (mostly beta-hydroxybutyrate)
Describe the effect of thyroid hormone on serum cholesterol?
(a) Hypercholesterolemia seen in hyper or hypothryoidism?
Thyroid hormone induces LDL receptor expression => increased cholesterol uptake by cells
(a) So hypercholesterolemia (more chol left in blood) 2/2 reduced LDL receptor expression seen in hypothyroidism
Hyperaldosteronism
(a) Clinical features
(b) pH abnormality
(c) Tx
Hyperaldo: high aldo causes retention of Na+ while dumping up K+
(a) Hypokalemia (=> weakness, tetany), sometimes HTN 2/2 hypernatremia, but often pt is normonatremic 2/2 compensatory diuresis
(b) Metabolic alkalosis
(c) Tx = Spironolactone = aldo receptor antagonist
What part of the hypothalamus produces
(a) ADH
(b) Oxytocin
Hypothalamic nuclei
(a) Supraoptic nuclei contains osmoreceptors that secrete ADH in response to low osmolality
(b) Oxytocin produced in paraventricular nuclei
How does 21-hydroxylase deficiency present in
(a) infancy
(b) childhood
21-hydroxylase (congenital adrenal hyplerplasia): low aldo, low cortisol, high androgens
(a) Infancy presents w/ salt wasting (2/2 low aldo)- extreme thirst and salt cravings, polyuria, hypotension => syncope or orthostatic symptoms
(b) presents w/ precocious puberty in childhood 2/2 high androgens
Can the following agents be used w/o any islet cell function?
(a) Metformin
(b) Glyburide
(c) Exenatide
(d) Sitagliptin
Islet cell function
(a) Metformin can be used in pts w/o islet function b/c it increases glucose uptake peripherally (improves insulin sensitivity)
(b) Glyburide (sulfonylurea) works to stimulate endogenous release of insulin => requires some islet fxn (useless in type 1)
Differentiate primary and secondary adrenal insufficiency
(a) Cause
(b) Clinical presentation
Primary adrenal insufficiency
(a) Due to adrenal damage (ex: Addison’s disease) where adrenal gland isn’t producing cortisol
(b) Presents w/ skin hyperpigmentation (2/2 elevated melanocyte secreting hormone as byproduct of ACTH), hypotension 2/2 hyponatremic volume contraction (b/c low aldo), hyperkalemia (b/c low aldo), metabolic acidosis
Secondary adrenal insufficiency
(a) pituitary reduced release of ACTH (so the adrenal gland itself is fine)
(b) No hyperpigmentation (b/c ACTH is reduced not elevated) and no hyperkalemia/hypotension (b/c aldo secretion is normal since controlled by RAS system)
- so just the symptoms of hypocortisol = fatigue, weakness, GI symptoms, wt loss
DKA ketones
(a) Ketone produced in the highest amount
(b) How ketones are measured
DKA ketones: 3 are produced- acetoacetate, beta-hydroxybutyric acid, and acetone
(a) Beta-hydroxybutyrate is produced in the highest amount
- accounts of the anion gap
(b) First start w/ urine dipstick that uses nitroprusside tablet just to see if there are ketones present, if positive can then do direct beta-hydroxybutyrate serum test to quantify
Diabetes drugs: wt loss of wt gain?
(a) metformin
(b) pioglitazone
(a) Metformin causes modest wt loss
(b) Pioglitazone (PPAR-alpha agonist) can cause wt gain
- also hepatotoxic
What is a craniopharyngioma?
(a) Presenting feature
Craniopharyngioma = Rathke pouch tumor arising from the pituitary stalk
(a) Presenting feature of bitemporal hemianopsia from mass effect causing compression of the optic nerve
What are Hurthle cells?
(a) 2 associated conditions
Hurthle cells = type of thyroid cell
(a) Associated w/ Hashimoto’s thyroiditis (autoimmune hypothyroidism) and follicular thyroid carcinoma
Hashimoto’s thyroiditis
(a) Symptoms- early vs. late in disease course
(b) Physical exam of thyroid
(c) Tx
(d) Increased risk of what malignancy?
Hashimoto’s thyroiditis
(a) In beginning may have hyperthryoid as follicular cells rupture and release contents, then hypothyroid as cells die off and are no longer producing hormone
(b) Moderately enlarged, non-tender gland
(c) Tx = thyroid hormone supplementation
(d) Increased risk of thyroid lymphoma, particularly B-cell non-Hodgkin’s lymphoma
GLUT2 receptors
(a) Function
(b) Location
GLUT2 receptors are low affinity
(a) Fxn to safe glucose for more vital tissues during fasting (so places like adipocytes and hepatocytes don’t uptake glucose during starvation)
- Also fxns to mediate glucose storage in hepatocytes during surplus
- Stimulate insulin release from beta-islet cells
(b) Hepatocytes, kidney, small intestines, beta-islet cells
What cells produce
(a) PTH
(b) Calcitonin
(a) PTH produced by chief cells of the parathyroid gland
(b) Calcitonin produced by parafollicular (C-cells) cells of the thyroid gland
Hormone reduced in congenital obesity
Congenital obesity: decreased levels of leptin
Clinical features of Cushing’s syndrome
(a) Main features
(b) Changes in appearance
Cushing’s syndrome = clinical findings of high cortisol levels
(a) HTN, Flushing, palpitations, wt gain, depression, weakness (2/2 catabolism of muscle for gluconeogenesis)
(b) Buffalo hump, striae, moon facies, truncal obesity, hirsuitism, easy bruising and thin skin (2/2 weakened collagen)
Also: immunosuppression, osteoporosis, hyperglycemia, amenorrhea
Causes of SIADH
Causes of SIADH
- head trauma, CNS disorder
- Ectopic ADH secretion (ex: small cell lung cancer)
- pulmonary disease
- drugs (ex: cyclophosphamide)
Name 3 clinical features of hypocalcemia
- tetancy
- ‘C’hvostek’s sign = ‘c’ontraction of facial muscles when tapped rapidly
- ‘T’rousseau’s sign = carpal sapsm following occlusion of brachial artery (‘t’ricep) w/ BP cuff
MC cause of secondary hyperparathyroidism
Chronic renal failure
-kidneys can’t reabsorb Ca2+ => hypocalcemia causes high PTH secretion
Which hypothalamic hormone secretion is regulated by prolactin
Prolactin regulates GnRH secretion from hypothalamus
-therefore prolactin regulates FSH/LH release (so ovulation/puberty etc)
How to treat pheochromocytoma
Pheo- imperative to first give alpha blockage, then give beta-block prior to tumor resection
-if give beta-block first then unopposed alpha-action can cause hypertensive crisis
How does calcium travel in serum?
Calcium travels
45% ionized (active form)
40% bond to albumin
15% bound to anions
Describe how demeclocycline can help in the tx of SIADH
Demeclocycline (tetracycline abx) works as an ADH antagonist => helps in SIADH
-but if not used in SIADH, can cause nephrogenic DI
Name congenital d/o w/ increased ghrelin production
Ghrelin production pathologically increased in Prader-Willi (paternal chromosome 15 microdeletion)
SIADH
(a) How is euvolemia maintained?
(b) Na+ status
SIADH = too much ADH produced => can’t get rid of excess water and pee out too much salt
End up with euvolemic (b) hyponatremic state
(a) Euvolemia b/c aldo secretion decreased in response to hyponatremia, maintaining a rather euvolemic state