Endocrine Part I Flashcards
Major endocrine glands
- pineal gland
- hypothalamus
- anterior pituitary
- posterior pituitary
- Thyroid
- parathyroid
- adrenal gland
- pancreas
- gonads
Pineal Gland
melatonin
Hypothalamus
GnRH, CRH, TRH
Anterior Pituitary
FSH, LH, TSH, ACTH, GH, Prolactin
Posterior Pituitary
oxytoxin, vasopressin
Thyroid
T3, T4, free T3, free T4, RT3
Parathyroid
PTH
Adrenal gland
cortex secretes, aldosterone, cortisol, sex hormones, medulla secretes epinepherine, norepinepherine
Pancreas
insulin, glucagon, others
Gonads
estrogen, androgens, testosterone
Type of proteins
insulin, GH, prolactin
Type of glycoproteins
FSH, LH, TSH
Types of polpeptides
ADH, glucagon
Types of Amines
T3, T4
Types of lipid-steroids
estrogen, cortisol, aldosterone, progesteron, testosterone
Glucocorticoid Indications
Usedforanti-inflammatoryand immunosuppressive actions; replacement in adrenal insufficiency
Long
actingdexamethasone[and betamethasone] can be used in suppression tests in an attempt to suppress ACTH
◦ To measure plasma cortisol levels for diagnosis of Cushing’s syndrome or excess glucocorticoid secretion from various etiologies
Glucocorticoid Production
Adrenal Cortex Produces:
- cortisol (glucocorticoid)
- aldosterone
- androgen
What does cortisol do?
Powerfulant
ainflammatory,modifiesimmunesystem and influences metabolic processes
RegulatedbyHPAaxisfeedback
Highestsecretion—0200until0700;lowest—1800
until midnight
Total10mg/dayinadults[physiologicaldose]
What does aldosterone do?
Underinfluenceofrenin-angiotensinsystem;regulates
Na+, K+, water retention
What are androgens?
sex hormones
What do Steroids do?
Affects metabolism of CHO/fats/proteins
Mineralocorticoid effects are related to K+, Na+, water and blood pressure regulation→Florinef®TM
Cortisone and hydrocortisone have glucocorticoid and mineralocorticoid effects;p&U
Synthetic analogs prednisone, prednisolone and methylprednisolone have what kind of effect?
glucocorticoid predominate
Triamcinolone, dexamethasone, betamethasone have what kind of effect
glucocorticoid anti-inflammatory effect only
Actions of CHO and protein
Stimulates liver gluconeogenesis and inhibits peripheral glucose use
Stimulates protein breakdown to amino acids which supports glycogen deposits and decreases glycolysis
Long term use of glucocorticoids causes
◦ Serum glucose ↑, glucose tolerance ↓, insulin
resistance, glycosuria
◦ Muscle atrophy, osteoporosis, impaired wound
healing, skin thinning; weight gain ◦ Growth impairment in children
Actions on Lipid Metabolism
Mobilization of fats from areas of deposition
Increases lipolysis
Increases deposits of fat in back of neck and
supraclavicular areas (buffalo hump), cheeks
and face (moon facies)
Loss off at in extremities
Action on Immune Response
Masks cellular and humoral immunity activity
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Can inhibit development of antibodies and impede ability to mount an effective response
◦ Action used to block transplant rejection
Redistribution of WBCs
What happens when there is a redistribution of WBCs/
◦ Can see an increased number of WBCs, but ↓ eosinophils, basophils, lymphocytes and monocytes in circulation—more in lymphoid tissues
◦ This decrease in circulating lymphs and macrophages alters immunity
Actions—Anti-inflammatory and Stress
Inhibits inflammation and immune response Actions useful in asthma and acute allergic
reactions, but can mask serious infection
Stress causes increased release of glucocorticoids, epinephrine and norepinephrine from adrenal medulla
◦ Steroids support catecholamines to increase HR, BP, glucose for “fight or flight” reaction
Adverse effects of steroids
Dermatological
◦ Acne, striae, skin-thinning, delay of wound healing
CV
◦ Increases BP, blood clots
GI
◦ PUD, pancreatitis, ulcerative colitis
Endocrine
◦ Menstrual changes, increases glucose, increases insulin need, hirsutism
MS
◦ Muscle mass loss, tendon rupture, femoral head
necrosis, fractures CNS
◦ Headache, vertigo, seizures, steroid psychosis Electrolytes
◦ Decreases K+, Ca++; Na+ retention
Ophthalmology
◦ Glaucoma, cataracts
What should you monitor with steroids
Short term therapy—Not needed
Long term therapy
◦ Monitor weight gain, edema, electrolytes, BP
◦ Monitor for infection
◦ Monitor withdrawal
◦ Monitor growth and milestones in children
◦ Monitor for fractures, osteoporosis, thin skin in elderly
Pregnancy
◦ Doses less than 20 mg/day no effect
◦ Higher doses monitor infant if breastfeeding
Patient Eduction with steroids
Carry wallet card Take with food before 9:00am Teach adverse effects Do not discontinue abruptly Avoid live vaccines if on oral Prednisone greater than or equal to 20 mg/day, [or its equivalent] Do not use in fungal infection
What does the endocrine system do?
Regulates growth, pubertal development, reproduction, homeostasis, and the production, storage and utilization of energy
Hormones are often activated by a feedback loop
Hormone
secretion can be regulated by nerve cells and the immune system
Hormones stimulate action in target organ to produce a hormone to control body functions
Normal Thyroid Function
Thyroid controls BMR, O2 use, respiratory rate, body temp, cardiac output, CHO/fat/protein metabolism, enzyme activity, growth and maturation
Thyroid released T4is90-99.97%protein bound while T3 is 10-99.7% protein bound
T4 is converted to T3 by removal of iodine– the body reduces T4 to T3, so usually only T4 is given as replacement
Unbound hormone is active or free [can now measure free hormone levels]
Elevated TSH indicates
hypothyroidism which is a failure within the thyroid gland
A low TSH with a low T3 and T4 is indicative of
secondary hypothyroidism from a lack of secretion of TSH from pituitary
CNS growth can be impaired without thyroid hormone
In children can cause mental retardation
In adults can cause CV, GI, MS and CNS function impairment
Hypothyroidism
Women more often affected
Signs and symptoms–tiredness, lethargy,
decreased BMR, cold sensitivity, menstrual irregularities
TSH most sensitive test
Can draw free T4 if diagnosis still in question after TSH results obtained
Symptoms of hypothyroidism
◦ Pale, puffy, expressionless face
◦ Cold dry skin, brittle hair
◦ ↓ heart rate, fatigue, lethargy, ↓ mental acuity
Common drugs for hypothyroidism
◦ Levothyroxine—Synthroid®TM [T4]
◦ Liothyronine—Cytomel®TM [T3]
◦ Armour Thyroid USP
Thyroid supplements
Thyroxine(T4)is used to treat uncomplicated hypothyroidism and is usually taken lifelong
Triiodothyronine(T3) is used in the suppression treatment of thyroid cancer
All drugs must be individualized to patient
STARTLOWANDGOSLOW!
Treatment based on labs and patient’s clinical
response; titration is done every 6-8 weeks [no sooner]
T4: Levothyroxine (Synthroid®TM) dosage
T4 converted to T3 in plasma–T3 is most active and has more risk for cardiotoxicity
Mean replacement dosage is 1.6mcg/kg/day
Give daily before breakfast; longt 1 ⁄2, can be
held for 2 weeks
75mcg=0.075mg
Adults<65 without CAD begin with50-100 mcg
Elderly or those with CAD begin with 25 mcg
Titrate with TSH level and clinical picture
Maintenance is usually75-150mcg
Pharmacokinetics is Levothyroxine
drug of choice (DOC)
T 1⁄2 6-7 days (euthyorid)
9-10 days (hypothyroid)
3-4 days (hyperthyroid)
Highly protein bound
Dosing for children—3-5 mcg/kg/day [to a max of 100-150 mcg]
Levothyroxine info
GI absorption is 50-80% Drug has narrow therapeutic range and absorption changes can make changes in blood level Cautious use with recent MI Do not stop drug abruptly Diabetes mellitus can be aggravated with initiation of the drug
Drug interaction with Levothyroxine
◦ Ferrous sulfate, Carafate, aluminum hydroxide antacids, estrogen, insulin, oral hypoglycemics, Digoxin, Warfarin
Toxicity of Levothyroxine
◦ Narrow TI, stop 3-5 days, then restart at lower dose
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Side effects of Levothyroxine
◦ CV – angina, arrhythmia, palpitations
◦ GI – abdominal cramps, n/v, diarrhea
◦ CNS – insomnia, headaches, nervousness
True or false: Generics are approved of levothyroxine and are equal
FALSE they are not. If you must use generic do not change manufacturers
**Many patients need brand name drug in order to be euthyroid
T3-Liothyronine [Cytomel] pharmacokinetics
T1⁄2 2-5days
Not protein bound
T3-Liothyronine [Cytomel]
Dosing
Adult—25 mcg increase by 25 mcg q 6-8 weeks [to a maximum of 100 mcg/d]
Elderly—5 mcg/d increase by 5 mcg every 6-8 weeks [maintenance is 25-75 mcg/d]
Children—5 mcg/d increase by 5 mcg every 3- 4 weeks to 20 mcg/d infants, 50mcg/d in children [ages 1-3]
Precautions with
T3-Liothyronine [Cytomel]
◦ Cardiovascular
Interactions with T3-Liothyronine [Cytomel]
◦ Cholestyramine , oral sulfonylureas,
estrogen, warfarin, phenytoin, cardiac glycosides
Dessicated-Armour Thyroid
Natural—ground up thyroid gland of a pig or cow
Ratio of T3/T4 varies from “batch to batch”
Erratic oral absorption
Bioabilability 50-75%
Prescribing this agent is not EB and not
supported by AACE
Do not give this agent!!
Goals of thyroid therapy
Return patient to the euthyroid state
TSH in the range of 0.5-4.0 IU/mL
Thyroid Hormone Pearls
Dose carefully-start low go slow Encourage compliance—morning dose or evening dose [2 hours after food] Teach signs and symptoms of hypothyroidism and hyperthyroidism Hold drug if HR>100 Caution changing manufacturers—use brand name if possible PregnancyCategoryA Caution with hx of CV disease/recentMI
Hyperparathyroidism
Grave’s Disease, toxic goiter, thyroiditis
Use drugs to suppress iodine so T4 cannot be
made
Once euthyroid(normal)for6-12months,
may decide to continue treatment for 12 months more, then try to stop – however, signs and symptoms may return
◦ Toxic goiter will never remit with short term use
of meds—will have to continue them for life, or have ablation with I131
Antithyroid Drugs
Antithyroid Agents ◦ Thiourea drugs ◦ Iodine salts & radioactive iodine Three mechanisms of action Interfere with hormone production Modify the response to the hormone Destroy the Gland
Thyroid suppressants
Propylthiouracil (PTU)[generic]
◦ 300-400 mg day; maintenance 100-150 mg day 45
Methimazole (TAPAZOLE®TM)daily
◦ Up to 60 mg day divide TID; maintenance 5-15 mg
day divide TID
Drugs block production of T4 and change to T3 – does not affect stored or circulating
hormones
Monitor blood count for agranulocytosis, infection with > 40 mg day; other drugs which suppress bone marrow has additive effect
Antithyroid Drug: Tapazole
◦ Most potent [10 x’s more potent than PTU] ◦ Category D ◦ Cross to breast milk ◦ Effects seen sooner ◦ Clears body faster ◦ Adult—5 mg q 8 hr [can be given once/d] ◦ Children—0.4 mg/kg/d [in divided doses every 8 hrs.]
Antithyroid Drug: PTU
💠CategoryD
💠Takes weeks to see effect 💠Short t 1⁄2 life—frequent dosing
💠Adult: 300-450 mg/day [divided q 8 hours]; maintenance dose is : 100-150 mg/day divided into BID or TID doses]
💠Children: 5-7 mg/kg/d [up to 300mg/day;
maintenance dose is 1⁄3 to 2⁄3 of initial dose]
Thyroid Suppressants
Avoid iodine ingestion [shellfish; kelp]
Drug interactions – Digoxin, anticoagulants
Can use β blockers for symptom control only
Adverse effects of thyroid suppressants
◦ Pruritic maculopapular rashes, arthralgia, & fever ◦ Leukopenia ◦ Hepatotoxicity ◦ Agranulocytosis ◦ Hypothyroidism
Other treatment options for hyperthyroidism
Radioactive iodine [I131]) Antithyroid agents Surgery Beta Adrenergic Receptor Agonists ◦ Propranolol [Inderal]; Nadalol [Corgard] Calcium Channel Blockers ◦ Diltiazem Iodide Salts ◦ Potassium iodide solution—SSKI [Lugol’s solution] Radioactive iodine ◦ Sodium Iodide 131
