Step Up- Endocrine Flashcards
Most common cause of hyperthyroidism
Graves disease
-IgG to TSH receptor (TSIg)
Young women
Three signs of hyperthyroidism that are specific to graves disease
Exopthalmos
Pretibial myxedema
Thyroid bruit
What is the purpose of a radioactive T3 uptake test?
The T3 can either be taken up by free TBG or by the resin that is given to the patient.
If the resin takes up the T3 as seen on the scan, then the TBG is likely saturated with T3 and therefore hyperthyroidism is a likely diagnosis.
This helps to diagenose true hyperthyroidism with elevated TBG
Normal free thyroxine index?
4-11
First line management of hyperthyroidism? Major side effect?
PTU and methimazole
Agranulocytosis
Contraindications to radioactive iodine treatment
Breastfeeding and pregnancy
Treatment of thyroid storm…
B-blocker for HR control
PTU
Dexamethasone to impair peripheral conversion of T4 to T3
Patients with hasimotos have increased risk of these cancers
thyroid lymphoma
thyroid carcinoma
Elevated TSH with normal T4
Subclinical hypothyroidism
antimicrosomal antibodies are increased in this form of hypothyroidism
Hashimoto’s
Subacute, or viral, thyroiditis is associated with this human leukocyte antigen…
HLA-B35
What is one of the defining physical finidings in subacte granulomatous thyoiditis?
PAINFUL thyroid
Ab present in chronic lymphocytic thyroiditis
antiperoxidase antibodies (90%)
antithyroglobulin antibodies (50%)
progressive replacement of the thyroid with fibrous tissue. Presents as painless hardened thyroid
Reidel’s thyroiditis
Characteristics that suggest malignancy in a thyroid nodule
- Fixed
- unusually firm
- solitary
- Hx of radiation
- Rapid growth
- Vocal cord paralysis
- Cervical adenopathy
- FMHx
- Elevated Serum Ca
First step in thyroid nodule evaluations
FNA (95% Sen and Sp.)
Which thyroid cancer is FNA NOT reliable for?
Follicular
Syndromes associated with thyroid cancer
Gardner’s syndrome and Cowden’s syndrome–> Papillary
MEN type II for meduallary thyroid cancer
Most common form of thyroid cancer
Papillary (also least aggressive)
Papillary thyroid cancer is most commonly associated witht his risk factor
radiation exposure
(Papillary is Pounded by radiation)
This form of thyroid cancer commonly matastasizes to distant organs (brain, bone, lung, liver)
Follicular
How does papillary thyroid cancer spread?
Via lymphatics
MEN II is associated with this form of thyroid cancer
Medullary
Medullary thyroid cancer is associated with this electrolyte distubance
Why?
Hypercalcemia
Cancer derived from parafollicular (c cells) which produce calcitonin
Worst form of thyroid cancer
anaplastic
What is the tx for most thyroid cancers?
Lobectomy (papillary) or total thyroidectomy (all others) with adjuvent radioiodine therapy
Medications associated with hyperprolacinemia
Psychiatric medications
H2 blockers
metoclopromide
verpamil
estrogen
Treatment of prolactinoma
bromocroptine (dopamine agonist)
Continue tx for 2 years before considering sugery unless otherwise indicated
Cabergoline may be better tolerated
Most common cause of death in patients with acromegaly
Hypertrophic cardiomyopathy (heart disease)
Levels of this are significantly elevated in acromegaly
Somatomedin C (IGF-1)
How does an oral glucose suppression test work?
If glucose load fails to suppress GH, this can confirm diagnosis of acromegaly
Normal serum osmolality
250-290
How to diagnose diabetes insipidis (neuro v. nephro v. psychiatric issue)
water deprivation test
Treatment for central DI
Desmopressin (nasal, oral, IM)
or Chlorpropamide and tx underlying cause
Tx for nephrogenic DI
discontinue offending agent
Sodium restriction and thiazide diuretic (depletes sodium leading to increased absorbtion in the proimal tubule of water and Na which decreases urine volume)
Is edema seen in SIADH? Why or why not?
NO
Despite hyponatremia, naturesis is occuring due to the increased release of atrial naturitic peptide and the inhibition of the Renin-angiotensin-aldosterone system
Treatments for SIADH id patient is asymptomatic
Water restriction
Loop diuretic
Lithium carbonate or demeclocycline (inhibit ADH in the kidney)
Danger of raising Na too quickly in SIADH?
Central pontine myelinolysis (replacement should no exceed 0.5meq/L/hr)
After establishment of cushing syndrome and high ACTH (or no suppression with low dose), how does the high dose dexamathasone suppression test work?
If the high dose dexamethasone does no suppress the production of ACTH the tumor is most likely and ectopic ACTH producing tumor–> Chest CT, abdominal CT and octreotide scan
If the suppression test does suppress then the tumor is most likely pituitary in origin–> head MRI
Pheochromocytomas are most commonly found here
adrenal medulla– arising from chromaffin cells
Rule of 10s for pheochromocytoma
10% familial
10% bilateral
10% malignant
10% multiple
10% in children
10% extra adrenal
How to diagnose pheo
Urine screen for metanepherine, VMA, HMA, and normetenepherine
Drug used to pretreat in removal of pheo
alpha blockade with phenoxybenzamine 10-14d prior to surgery
propanolol 2-3d prior
(alpha blockade for BP abd Beta for HR)
MEN type I is composed of these abnormalities
Parathyroid hyperplasia
pancratic islet tumors
pituitary tumors
MEN IIA is composed of these clinical findings
(MPP)
Medullary thyroid carcinoma
Pheochromocytoma
Pharathyroid abnormalities
MEN IIB is composed of…
“MMMP”
Mucosal neuromas
Medullary thyroid tumors
Marfanoid body
Pheo
electrolyte disturbance present in hyoeraldosteronism
Sodium retention
Hypokalemia
Metabolic alkylosis (loss of H+ in the mudullary collecting tubules)
Most common cause of hyperaldosteronism
Adrenal adenoma– conn syndrome most common
Adrenal hyperplasia (almost always bilateral)
Rarely adrenal carcinoma
laboratory study to evaluate for hyperaldosteronism
plasma adosterone:renin ratio >30
inappropriately elevated aldosterone with a decrease in renin activity
Confirmatory test for hyoperaldosteronism (there are two)
- Saline infusion test
Infusion of saline should result in decrease in plasma aldosterone in normal patients. It will not in patient with hyoperaldosteronism
- Oral sodium loading
- should result in decreased aldosterone. Increased aldosterone in the setting of increased urine sodium confirms the diagnosis
How can venous versus arterial blood elucidate the cause of hyperaldosteronism
Aldosterone high on venous side= adenoma
Aldosterone high on venous and arterial side= hyperplasia
Tx for aldosterone producing adeoma
Tx for bilateral hyperplasia
Resection for adenoma
Spironolactone for bilateral hyperplasia
Most common infectious cause of primary adrenal insufficiency worldwide? Industrialized nations?
Tuberculosis
Idiopathic (likely autoimmune) addison disease
Most common cause of secondary adrenal insufficiency?
Long term steroid therapy
Symptoms of lack of cortisol?
GI pain
Hypoglycemia
Hyperpigmentation (due to increased ACTH and melanocyte stimulating hormone)
hypotension and shock
Hyponatremia and hypovolemia
Hyperkalemia
How do the treatements for primary and secondary adrenal insufficiency difffer?
Primary: both glucocorticoid (prednisone/hydrocortisone) need to be replaced due to low cortisol and low aldosterone
Secondary: Glucocorticoid replacement is necessary but mineralocorticoid is not because aldosterone is normal
This enzyme is the most commonly deficient enzyme in congenital adrenal hyperplasia
21-hydroxylase
High levels of this enzyme are present in individuals with 21-hydroxylase deficiency
17-hydroxyprogesterone
What is the pathophysiology of congential adrenal hyperplasia and how it causes virilization?
As precursors to 21-hydroxylase build up they are shunted to synthesis of androgens (DHEA and Testosterone)
–Females born with ambiguous genitalia but normal uterus and ovaries
What major electrolyte disturbance is associated with congenital adrenal hyperplasia?
Hyponatremia and hyperkalemia dye to lack of mineralocorticoid
Difference betwen dawn phenomenon and symogyi effect
Dawn phenomenon: morning hyperglycemia in response to growth hormone
Symogyi effect: morning hyperglycemia in response to nocturnal hypoglycemia
This hyperglycemic agent is contraindicated in patients with renal failure
Metformin
Hyaline deposition in one area of the kidney (nodular glomerular sclerosis) is pathognomonic for this….
Diabetic nephropathy
Why may ketones be falsely negative in ciruclatory collapse?
The production of lactate shifts the production of ketones to B-hydroxybtyrate over acetoacetate. Acetoacetic acid is normally the one that is measured.
Sodium correction in DKA
Add 1.6 to measured Na for every 100 mg/dL increase in glucose.
What causes the need for Na correction in DKA
glucose causes osmotic shift of fluid from ICF to ECF thus diluting the Na.
Describe the changes in potassium that are caused by DKA
Initially hyperkalemia due to shift from acidosis
Insulin and overall loss in the urine causes intracellular shift of K leading to dangerous hyperkalemia
ALWAYS A TOTAL DEFICIT
Findings in hyperosmolar, hyperglycemic, non-ketotic state?
Hyperosmolarity– due to osmotic diuresis
Hyperglycemia
non-ketotic– due to enough basal insuline to suppress ketogenisis
This should always be given before or with glucose in hypoglycemia
Thiamine to avoid wenicke encephalopathy
Insulinoma is assocaited with this syndrome
MEN1
Gastrinoma, also known as
zollinger-ellison syndrome– a pacreatic islet cell tumor that secrets gastrin
Leads to high gastric acid levels and ulcers
Gastrinoma triangle
cystic duct superiorly, second and third portion of duodenum inferiorly, and neck of pancreas medially
In zollinger-ellison syndrome, gastrin increases substantially after administration of this…
secretin
Glucagonoma is associated with this dermatologic manifestation
necrotizing migratory erythema
watery diarrhea, achlorhydria, hyperglycemia and hypercalcemia
VIPoma
