Endo Block 1 Flashcards
For endocrine homones what are the biological active fraction, bound or unbound
Unbound (free)
What are the two basic classes of hormones
polypeptides (proteins) and steroids (thyronines)
How are steroids chaparoned thoughout the body
By binding to a protein
High levels of circulating hormone produces what in negative feedback
Decreases hormone synthesis and secretion
Low levels of circulating hormone has what response in negative feedback loops
Increase hormone synthesis
In hyperfunction of endocrine tissue what is primary disfunction
Alteration of the hormone secreting gland
In hyperfunction in endocrine tissue what is secondary disfunction
Alteration in pituitary or hypothalumus
What is ectopic endocrine tissue disfunction
Hormone secreted from tissue other tahn usual sourse
What is resistnce endocrice disfunction
Inability of target tissue to recognize the hormone
What is an adenoma
Adenoma—benign enlargement of a cluster of glandular (secreting) cells
Can become malignant (i.e. adenocarcinoma)
What is a neoplasm
Neoplasm—abnormal new growth of tissue
Generally considered malignant
What is hyperplasia
Hyperplasia—benign enlargement of entire gland
What is the differnce between atrophy and hypoplasia
Atrophy – the wasting away of existing cells
Hypoplasia – underdevelopment or incomplete development (congenital)
What is the single best screening lab for someone with hypothyroidism
Screen the pituitary ( TSH)
What are the two hormones secreted from the posterior pituitary gland
Oxytocin and ADH
Is the post pituitary a gland
Not a gland but is the distal axon terminals of the hypothalamic neurons
What are the two receptors for ADH
V1 and V2
V1 receptors are found in blood vessels, constricts vascular smooth muscle (however it is a weak pressor)
V2 receptors are found in the collecting duct of the kidney, and they cause water to be retained in the body
The major function of ADH is to retain water in the body
What is the major function of ADH
NO PEEING, to retain water in the body
What is the response of ADH to osmolarity increases
ADH is released
Where are the V2 receptos for ADH
Works in the collecting tubel and increases aquaporins to increase water absorption
What are the two regulators for ADH secterion
#1 - Osmoreceptors in hypothalamus -1% INCREASE in plasma osmolality releases ADH
#2 - Baroreceptors in arteries and atria -10% or greater DECREASE in plasma volume or pressure, releases ADH
What effect does alcohol have on ADH secretion
Inhibits ADH and increase urine output
What is SIADH
Too much ADH, SI makes you SWELL! Retain fluid
What is Diabetes insipidus
Not enough ADH, DI makes you DRY, PEE OUT ALL YOUR FLUID
What are the initial clues of SIADH
normal or expanded plasma volume, but NOT low plasma volume
low serum sodium (hyponatremia)
high urine specific gravity (SG)
high urine sodium
What are the top three causes of SIADH
Central nervous system or lung disorders
Malignancy - tumors which secrete ectopic ADH
Prescription and recreational drugs
80 percent of lung tumors associated with SIADH are..
Small cell lung cancer
A pt presents with unexplained hyponatremia and oliguria/ anuria…
What should you order
Chest Ct or MRI r/o malignancy
What effect does antineoplastic medication have on ADH
Increased secretion (SIADH) due to nausea mechanism
What effects for NSAIDs have on ADH
Increase ADH by inhibiting prostaglandins
What medications induce SAIDH
Antidepressants ( SSRI, TCA, MAOI)
Anti neoplastic agents ( that cause nausea)
MDMA- Exctasy
NSAIDs
Opiates
Low Na+ in the setting of SIADH is due to…
Excess water, not lack of sodium
What are the early S/s of low serum Na+
Fatigue
HA
Nausea
What are late signs of Low serum Na+
Letharfy, confusion, stupro, and coma
Neuromuscular excitabilty, muscle twitching a SZR, from electrolyte abnomrl
Vomiting and abdominal cramps
What are the labs values in SIADH
Low plasma osmololity
W/ normal plama volume
HypoNa+ (<135)
High urine osmololity compared to plasma (>20mEq/dL)
Low BUN (<10 mg/dL) Hypouricemia
What is the Tx approach to euvolemic, aS/s or mild S/s of SIADH
Water restriction
Demeclocycline ( if the pt cant adhere to water restriction)
Ensure adequate dietary Na+ intake
What is the Tx appraoch to S/s and severe hyponatremia
Raise serum Na+ by o.5-1 mEq/ hr to a max 125-130 (avoid locked in syndorme) No more than 8-10 mmol in a 24 hour period
3% hypertonic saline– for emergencies only (CNS symptoms present)
-Seizures, confusion, etc.
Furosemide—increases free H2O excretion
Tolvaptan (V2 receptor antagonist) – mediates the diuretic effect of ADH
These medications would be used in consultation with a nephrologist
Monitor serum sodium levels frequently (q 1-2 hours)
What is the referral criteria for SIADH
Nephrology or Endocrinology referral for SEVERE, uncertain, refractory, or complicated cases
If AGGRESIVE therapies are needed, such as with hypertonic saline, demeclocycline, V2 receptor antagonists, or dialysis
In patients with end liver or heart disease
A pt presents with 2-20 L of urine production in 24 hours think
Diabetes insipidus
What is a normal urine osmolality
300 mOsm/kg
What are the 4 main types of DI
Central (important)
Nephrogenic (important)
Primary Polydipsia
Gestational
What causes nephrogenic DI
Decreased ability to concentrate the urine due to resestance to ADH in the kidney
What is sheehan syndrome
Massive blood loss post parturm, leading to hypovolemic shock and pituitary infarction ( may cause DI)
What are the common causes of Nephrogenic DI
Medications like LITHIUM, demeclocycline, ETOH, CAFFINE, Wt loss medicaions
Hypokalemia and hypercalcemia
Renal Dz
A pt presents with polydispsia, polyuria with a normal serum sodium, (with possible nocturia)
Think ?
Classic presentation of DI
How does an unconscious pt present with DI
HOTN, vascular collapse, Hypernatremia
What is a urine output volume that would r/o DI
Less than 2L in 24 hrs
What is a vasopressin challange test
A w/u for central DI Dx
Patient is admitted to hospital
-Give desmopressin acetate (0.05-0.1 mL/1mcg)*intranasally, subcutaneously or intravenously
Measure urine volume before for 12 hrs, then after DDAVP
Measure serum sodium at baseline, 12 hours after DDAVP
If pt has Central DI, they will have decreased thirst, decreased urine output, increased urine osmolality
A pt with an elevated ADH during fluid restriction
Think
DI
What is the Tx approach to Central DI
DDAVP, lowest effective dose 2-3 x a day
Monitor elecrtrolytes
Avoid dehydration ( V/D)
What is the tx appraoch to Nephrogenic DI
Indomethacin 50 mg q 8hrs
What is the adenohypophysis
The anterior pituitary
What is the relationship with ACTH and MSH
ACTH stimulates alpha-MSH in the Ant. Pituitary
What is the effect of pregnancy on the Ant. Pituitary
Doubles in size
What is the diff between clinically functioning and non functioning pit. Adenomas
Functioning is secreting at least 1 hormone, non functioning is not and typically found on accident
What is the diff between macro and micro adenomas
Macro : >1 cm and micros are less
What is the procedure of choice to investigate a pituitary problem
MRI!
What effect does dopamine agonists and somatostatin have on Prolactin secrtion
Decrease/ Block the secretion
What is bromocriptine
A dopamine agonist that can suppress the secretioin of Prolactin
What is a normal prolactin level
Less than 20mg/dl is normal
What effect does glucose have on Growth Hormone
Hyper glycemia suppresses Growth Hormon secretioin, Hypoglycemia stimulates Growth Hormone production
What is the Tx of choice for Acromegaly
Transsphenoidal resection (SRGRY)
What cardiac conditions are assoc. with acromegaly
Valvular regurgitation and persistant HTN
What is cushings “disease”
A cortisol hormone d/o that comes from the brain ( secondary)
What is cushings “syndrome”
Primary adrenal problem with cortisol
What is the most common cause of cushings syndrome
Taking too much corticosteroids
A pt presents with central obesity, facial plethora, thin skin with easy bruising, proximal muscle weakness, HTN and DM
Think?
Hypercortisolism ( adrenal, ACTH problems)
What is the test to assess corticotropic adenomas
A dexamethasone supression challange
and a 24 hour urine
What is the Tx of choice for a Cushings Disease
Surgical removal of the tumor
A pt presents with sudden severe headache, AMS, Vomitting, Ocular defects, with HOTN
Think
Pituitary D/o likely hypo
In hypopituitary d/o what are the order of loss hormones
GH is lost first
What are the common S/s of hypothroidism
Fatigue, letharfy, constipation , depression, wt gain, cold intolerance, dyspnea on execrtion, menorraghia, arthlagias, parasethisias
(Metabolism is down)
How with DTRs present with hypothyroidism
Delayed relaxation
What is the single best test to evaluate hypothyroidism
TSH
May be increased/ elevated in primary
And may be low in secondary
What is a normal TSH level
0.4-4.0 mL/L
When should TSH be checked after starting levothyroxine tx
Not until after 6 weeks!
How should levothyroxine for hypothyroidism be taken
Must take in the AM, without other food or drugs,
At least 4 hours before other drugs
LONG TERM!
What is the dosing regiment for levothyroxine
Start at 50 mcg/ day then increase q 6 weeks by 25-50 mcgs until target dose is reached
(1.6 mcg/kg/day)
What is the TSH goal for hypothyroidism Tx
A TSH between 04.-2.0 mL/L
What effect does pregnancy have on Levothyroxine Tx
Dosage requires in the 5th week of pregnancy a 20-30% increase
A pt with hypothyrdoidism + hypercapnia, + myxedema coma… what do you do
ADMIT!
What is cretinism
Congenital hypothyroidism
Hypoplastic or failure of the thyroid to migrate to its appropriate location
Usually heriditary from hashimotos
S/s: slow mentation, slow bone development, decreased longitudinal growth, Thick dry scalp, with delayed sexual maturation
Tx: levothyroxine
Resting tremor is a sign and symptom of what D/o
Hyperthyroidism
How does Graves Dz present
High Thyroid s/s
Bruit + enlarged thyroid
Non pitting edema
SubQ infitrates
Exopthalmos
What is thyroid acopathy
Swelling/ clubbing of the fingers seen in graves dz
A pt presents with LOW TSH and High T3 T4 think
Hyperthyroidism, Graves Dz
What are the Tx approachs to Hyperthyroidism
Methimazole
Proprothyuricil ( pregnant seeking pts)
Surgery
S/s control with b blockers
radioactive therpay
What are the ADE of Tx of hyperthyroidism
Rash, agranulocytosis, N/ dyspepsia, Liver failure with PTU 1:1000
What are Orargrafin and telepaque
Bridge therapy to surgery for hyperthyroidism
Used for severe S/s
What is the Tx of Choice for Graves Dz (Hyperthyroidism)
Ablation of the thyroid with radiation
What is the Tx appraoch to exopthalmos
Corticosteroids (treat during the ablation of the thyroid)
What are the three indications for surgery of the thyroid in hyperthyroidism
Large obstructive gland, risk of malignancy, or pregnant women with uncontrolled S/s
What is the most common type of thyroid cancer
Papillary
What is the most aggresive form of thyroid cancer
Anaplastic
Which is also the least common
What is the most sig RSK fx for development of papillary thyroid cancer
Exposure to radiation
What is the Tx of choice for Thyroid Cancer
SURGERY
Post surgical RAI is only effective on what two types of thyroid cancer
Papillary and follicular
What is the tx approach to thyroid storm
Admit to ICU
+propranolol
+ Proprylthiuricil
+ Corticosteroids
B Blockers can be used for cardiac S/s
What is the Tx approach to myxedma coma
IV levothyroxime
Supportive care, passive warming, electrolyte correction
Where does ACTH have its action in the adrenal gland
Reticularis and Fasciculata