Endocrine, Thyroid, Hypoglycermics, and Steroids Flashcards
Endocrine Physiology
Body homeostasis is controlled by 2 major systems
Nervous System
Endocrine aka Hormonal System
Endocrine Physiology
The purpose of the Endocrine system is regulation…
The purpose of the Endocrine system is regulation of behavior, growth, metabolism, and fluid and electrolytes
Endocrine Physiology
Endocrine glands are mediated by hormones and secrete their hormones directly into…
Endocrine glands are mediated by hormones and secrete their hormones directly into “surrounding extracellular fluid”
Mechanism of Hormone action
Hormones bind to, what two?, receptors to trigger selective and diverse cellular responses.
Hormones bind to “membrane” and “nuclear” receptors to trigger selective and diverse cellular responses.
Mechanism of Hormone action
Membrane receptor binding (peptides and catecholamines) initiates signal transduction through enzymes such as…
Membrane receptor binding (peptides and catecholamines) initiates signal transduction through enzymes such as “adenylate cyclase, tyrosine kinase, and serine kinase.”
Mechanism of Hormone action
Receptor binding in the nucleus regulates gene expression in the BLANK and nucleus to produce what two things?.
Receptor binding in the nucleus (steroids and vitamin D) regulates gene expression in the “cytoplasm” and nucleus to produce “specific intracellular proteins and enzymes.”
Pituitary Gland
The Pituitary Gland is the size of a what?
The Pituitary Gland aka hypophysis
Size of a pea
Pituitary Gland
Connected to the hypothalamus by what?
Connected to the hypothalamus by pituitary stalk
Hypothalamus and pituitary gland
The hypothalamus is located where in relation to the thalamus, optic chiasm, and optic tracts?
The hypothalamus is below the thalamus behind the optic chiasm and between the optic tracts
Hypothalamus and pituitary gland
The pituitary gland and hypothalamus is there a BBB?
The pituitary gland & hypothalamus have NO BBB
Hypothalamus
Hypothalamus collects and integrates what four things?
Hypothalamus collects and integrates, pain emotions, energy, H2O balance, olfactory sensations and electrolyte sensations
Pituitary gland
The pituitary gland is divided what two structures?
The pituitary gland is divided anteriorly and posteriorly
What is the largest part of the pituitary gland?
Largest part of the pituitary gland, approx 80% of its weight
The anterior pituitary glad secretes what 6 major peptide hormones and 1 lipotropin?
GH/ Somatotropin
ACTH/ Corticotropin
Thyroid Stimulating Hormone/ TSH
Follicle Stimulating Hormone/ FSH
Luteinizing Hormone/ LH
Prolactin
The anterior pituitary also secretes β-lipotropin, which contains the amino acid sequences of several endorphins that bind to opioid receptors (Flood)
ACROMEGALY/ gigantismanterior Pituitary disorder
Is a hypersecretion of which hormone? which is usually caused by what?
Hypersecretion of GH usually caused by GH secreting pituitary adenoma 99% of the time
ACROMEGALY/ gigantismanterior Pituitary disorder
Caused by excessive action of, what what?, after adolescence leading to anatomical changes and metabolic dysfunction
Caused by excessive action of “GH and IGF-1” after adolescence leading to anatomical changes and metabolic dysfunction
GH hypersecretion prior to, what stage of life?, will cause the individual to grow 8-9 feet tall?
GH hypersecretion prior to “puberty” ie before closure of the growth plates can cause the individual to grow 8-9 feet tall
ACROMEGALY/ gigantismanterior Pituitary disorder
Common Features of Acromegaly?
Common Features of Acromegaly
- Skeletal overgrowth- enlarged hands and feet, prognathic mandible
- Soft tissue overgrowth- enlarged lips, tongue, epiglottis distorted facial features
- Visceromegaly- enlarged liver, spleen, kidney and heart
- Hypertension
- Cardiomyopathy
- Osteoarthritis
- Glucose intolerance
- Peripheral neuropathy
- Skeletal muscle weakness
- Extrasellar tumor extension- headache, visual field defects
- Decreased life expectancy- cardiac and respiratory issues
Pharmacological treatment for Acromegaly?
-Octreotide or lanreotide (somatostatin receptor ligands)
Inhibits release of GH*
Long term use increase incidence of gallstones
Hyperglycemia and decreased glucose tolerance
- Cabergoline- dopamine agonist
- Pegvisomant GH receptor antagonist
-Stress dose of glucocorticoid therapy
Decrease synthesis of 1,25-dihydroxyvitamin D to decrease intestinal absorption of calcium increase renal excretion of calcium
Posterior pituitarysecretes what two Hormones?
Arginine Vasopressin (AVP)/ ADH
Oxytocin
What are the functions of AVP/ADH?***
Functions of Arginine Vasopressin (AVP)/ ADH
Vasoconstriction V1
Water retention V2
Corticotropin secretion V3
What stimulates the release of AVP/ADH?
Stimulates Arginine Vasopressin (AVP)/ ADH
release:
- Decrease blood volume
- Increase plasma osmolality
- Decreased arterial pressure
What does Oxytocin do?
Stimulates uterine smooth muscle contraction during labor and decreases post partum bleeding
High boluses decrease SBP & DBP via direct effect on vascular smooth muscles (us giving it)
Oxytocin causes what to heart rate and what happens in high doses?
- Reflex tachycardia & increased CO
- In high doses water intoxication, hyponatremia, neurologic dysfunction if excessive volume of fluid administered
What are the posterior pituitary drugs?
Vasopressin
Desomopressin DDAVP synthetic AVP- ( Nasal dose: Lypressin)
What is the recommended infusion rate for Tx of shock in adults with Vasopressin??**
Vasopressin
The recommended infusion rate in the Tx of shock in adults is 0.01-0.04 units/min**
Vasopressin is not recommended for what disorder?***
Not recommended for nephrogenic DI***
What is Vaopressin used to treat?
- Tx AVP DI
- Refractory hypotension
- Uncontrolled hemorrhage esophageal varices- hepatic blood flow
- Septic shock
- Refractory cardiac arrest
Desomopressin DDAVP synthetic AVP- ( Nasal dose: Lypressin) is used to treat what?**
Treatment of AVP/ADH deficiency
Tx of central DI NOT recommended for nephrogenic DI**
Desomopressin DDAVP synthetic AVP
Increases levels of which clotting factors?
Increases levels of von Willebrand factor & factor VIII
Reverses coagulopathy associated with platelet adhesion defects including coagulopathy of renal failure
Diabetes insipidusinadequate secretion of???
Diabetes insipidusinadequate secretion of “ADH/AVP”
Destruction of neurons in or near the, what two structures?, of the hypothalamus may decrease vasopressin release to cause central diabetes insipidus.***
Destruction of neurons in or near the “supraoptic and paraventricular nuclei” of the hypothalamus from pituitary surgery, trauma, cerebral ischemia, or malignancy may decrease vasopressin release to cause central diabetes insipidus.***
What can cause damage to the neurons of the hypothalamus that may decrease vasopressin levels to cause ventral DI?**
Pituitary surgery, trauma, cerebral ischemia, or malignancy may decrease vasopressin release to cause central diabetes insipidus.***
If the posterior pituitary alone is damaged, however, the transected fibers of the pituitary stalk can still continue to secrete BLACK.
If the posterior pituitary alone is damaged, however, the transected fibers of the pituitary stalk can still continue to secrete “AVP.”
Diabetes insipidus from lack of vasopressin release during pituitary surgery is usually BLANK.
Diabetes insipidus from lack of vasopressin release during pituitary surgery is usually “transient.”
What are the hallmark signs of Diabetes Insipidus???**
- Hallmark sign is polyuria which results in dehydration and HYPERnatremia ( Na > 145 mEq/L).
- Serum osmolarity ( >290 mOsm/L)
- Urine output greater than 2 mL/kg per hour
- Urine osmolarity HYPOtonic relative to plasma**
What is the treatment for Diabetes insipidus?***
Treatment***
- DDAVP or Vasopressin V2
- Chlorpropamide (sulfonylurea hypoglycemic agent)
- Carbmazepine (anticonvulsant)
- Thiazide diuretics
What is syndrome of antidiuretic hormone?
Disorder characterized by high circulating vasopressin levels relative to plasma osmolarity & serum sodium concentration
What are the clinical features of syndrome of antidiuretic hormone
- Water intoxication
- Dilutional hyponatremia
- Brain edema
- Lethargy
- Headache
- Nausea
- Mental confusion
- Seizures
- Coma
What are the hallmark signs of syndrome of antidiuretic hormone?**
Serum osmolarity less than 270 mOm/L
Serum sodium less than 130 mEq/L
Urine volume LOW
Urine osmolarity HYPERtonic relative to plasma*
What is the treatment for syndrome of antidiuretic hormone***
Treatment**
- Fluid restriction 0.9% normal saline 800-1000 ml per day
- If patient symptomatic of Na 115-120 mEq/L consider hypertonic saline
What are the hormones secreted from the thyroid?
- T4 Thyroxine- 80% of body’s hormone production- prohormone synthesized from tyrosine
- T3 Triiodothyronine 5x more active than T4 produced from tyrosine production
-Thyroid-stimulating hormone (TSH)
Stimulated by the ANTERIOR pituitary
What does the Thyroid do?
- Maintains optimal metabolism for normal tissue function
- Increases O2 consumption in nearly all tissues except the brain
- Secretes calcitonin which is important for calcium ion use
Hypothyroid has a decrease concentrations of what? and increased levels of what?
Hypo-function with decreased circulating concentrations of T3 and T4 hormones
Increased levels of TSH
What is the most common thyroid disorder?
HypoThyroid
What is Hashimoto thyroiditis?
Autoimmune mediated hypothroidism
What are some Iatrogenic causes of Hypothroidism
Iatrogenic causes
Surgery, neck irradiation and radioiodine therapy
What two things are seen with hypothyroidism?
Iodine deficiency
Colloid goiter
What is the treatment for hypothroidism?
Treatment
- Primary Tx is hormone replacement
- TSH is monitored in Primary hypothyroidism
- T4 is monitored in Secondary hypothyroidism TSH released is impaired
What can you use for thyroid hormone replacement for Hypothyroid?***
Synthetic Thyroxine Levothyroxine Sodium T4 (Tx of choice)*
Synthroid, Levoxyl*
- Long ½ life 7- 10 days
- Once a day dosing
- Maintains physiologic levels of T3- active hormone
What are some side effects of hypothyroid hormone replacement?
Side effects
- Patients with existing angina pectoris or underlying CAD requires careful monitoring
- Myocardial O2 consumption is augmented by thyroid hormone
- Patients with deficient coronary artery circulation may not tolerate full replacement dose
What is a long term treatment for Hypothyroid?***
Treatment ( Long term)
T3 formulations*
Liothyronine isomer of T3*
- 2-3 times as potent as Levothyroxine
- Rapid onset & short duration
- Used for long term replacement
What are the goals of therapy for Hypothyroid?
- Correction of hypothyroidism to euthyroid
- Reduction in goiter
- Prevention of Thyroid Ca recurrence
What is thyrotoxicosis?
What is the most common cause?
Defined as thyroid hormone excess
Most common cause of thyrotoxicosis is Graves Disease
What is Graves disease?
Autoimmune disease which TSH receptor antibodies bind & stimulate thyroid gland resulting in gland enlargement and excessive production of T3 and T4
Graves disease occurs most commonly in what population?
More common in women 40-60 years of age
3 fold increase incidence in post partum period
What are the potential risk associated with graves disease?
Potential risk cigarette smoking and stress
Other causes of Thyrotoxicosis, besides Graves disease?
- Toxic Nodular Hyperthyroidism
- Thyroiditis causes increased released hormones
- Thyroid Cancer associated with euthyroid may cause hyper or hypo thyroidism
- Iodine containing radiocontrast or angiography dyes
- Amiodarone is iodine rich and may cause hyper or hypothyroid**
How do you determine Hyperthroid/thyrotoxicosis?
Diagnosis TSH levels and measurement of free T3 and T4.
Once steady state maintained you can measure TSH
What are the treatments for Hyperthyroid/thyrotoxicosis?
TREATMENT
- Radioactive gland ablation
- Surgery
- Antithyroid medications
What is Methimazole?***
THIONAMIDES- Anti-thyroid medication
METHIMAZOLE ½ life 4-6 hours QD dosing
Crosses the placenta appears in breast milk*
What is Propylthiouracil (PTU)?**
THIONAMIDES- Anti-thyroid medication
PROPYLTHIOURACIL (PTU) ½ life 75 min dosed several times per day
Hepatic toxicity*
Preferred drug for parturient*
What are three Thionamides?
METHIMAZOLE
CARBIMAZOLE
PROPYLTHIOURACIL (PTU)