Endocrine Part I Flashcards
1
Q
Major endocrine glands
A
- pineal gland
- hypothalamus
- anterior pituitary
- posterior pituitary
- Thyroid
- parathyroid
- adrenal gland
- pancreas
- gonads
2
Q
Pineal Gland
A
melatonin
3
Q
Hypothalamus
A
GnRH, CRH, TRH
4
Q
Anterior Pituitary
A
FSH, LH, TSH, ACTH, GH, Prolactin
5
Q
Posterior Pituitary
A
oxytoxin, vasopressin
6
Q
Thyroid
A
T3, T4, free T3, free T4, RT3
7
Q
Parathyroid
A
PTH
8
Q
Adrenal gland
A
cortex secretes, aldosterone, cortisol, sex hormones, medulla secretes epinepherine, norepinepherine
9
Q
Pancreas
A
insulin, glucagon, others
10
Q
Gonads
A
estrogen, androgens, testosterone
11
Q
Type of proteins
A
insulin, GH, prolactin
12
Q
Type of glycoproteins
A
FSH, LH, TSH
13
Q
Types of polpeptides
A
ADH, glucagon
14
Q
Types of Amines
A
T3, T4
15
Q
Types of lipid-steroids
A
estrogen, cortisol, aldosterone, progesteron, testosterone
16
Q
Glucocorticoid Indications
A
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
17
Q
Glucocorticoid Production
A
Adrenal Cortex Produces:
- cortisol (glucocorticoid)
- aldosterone
- androgen
18
Q
What does cortisol do?
A
Powerfulant
ainflammatory,modifiesimmunesystem and influences metabolic processes
RegulatedbyHPAaxisfeedback
Highestsecretion—0200until0700;lowest—1800
until midnight
Total10mg/dayinadults[physiologicaldose]
19
Q
What does aldosterone do?
A
Underinfluenceofrenin-angiotensinsystem;regulates
Na+, K+, water retention
20
Q
What are androgens?
A
sex hormones
21
Q
What do Steroids do?
A
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
22
Q
Synthetic analogs prednisone, prednisolone and methylprednisolone have what kind of effect?
A
glucocorticoid predominate
23
Q
Triamcinolone, dexamethasone, betamethasone have what kind of effect
A
glucocorticoid anti-inflammatory effect only
24
Q
Actions of CHO and protein
A
Stimulates liver gluconeogenesis and inhibits peripheral glucose use
Stimulates protein breakdown to amino acids which supports glycogen deposits and decreases glycolysis
25
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
26
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
27
Action on Immune Response
Masks cellular and humoral immunity activity
12
Can inhibit development of antibodies and impede ability to mount an effective response
◦ Action used to block transplant rejection
Redistribution of WBCs
28
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
29
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
30
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
31
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
32
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
```
33
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
34
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]
35
Elevated TSH indicates
hypothyroidism which is a failure within the thyroid gland
36
A low TSH with a low T3 and T4 is indicative of
secondary hypothyroidism from a lack of secretion of TSH from pituitary
37
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
38
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
39
Symptoms of hypothyroidism
◦ Pale, puffy, expressionless face
◦ Cold dry skin, brittle hair
◦ ↓ heart rate, fatigue, lethargy, ↓ mental acuity
40
Common drugs for hypothyroidism
◦ Levothyroxine—Synthroid®TM [T4]
◦ Liothyronine—Cytomel®TM [T3]
◦ Armour Thyroid USP
41
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]
42
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
43
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]
44
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
```
45
Drug interaction with Levothyroxine
◦ Ferrous sulfate, Carafate, aluminum hydroxide antacids, estrogen, insulin, oral hypoglycemics, Digoxin, Warfarin
46
Toxicity of Levothyroxine
◦ Narrow TI, stop 3-5 days, then restart at lower dose
| 35
47
Side effects of Levothyroxine
◦ CV – angina, arrhythmia, palpitations
◦ GI – abdominal cramps, n/v, diarrhea
◦ CNS – insomnia, headaches, nervousness
48
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
49
T3-Liothyronine [Cytomel] pharmacokinetics
T1⁄2 2-5days
| Not protein bound
50
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]
51
Precautions with
| T3-Liothyronine [Cytomel]
◦ Cardiovascular
52
Interactions with T3-Liothyronine [Cytomel]
◦ Cholestyramine , oral sulfonylureas,
| estrogen, warfarin, phenytoin, cardiac glycosides
53
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!!
54
Goals of thyroid therapy
Return patient to the euthyroid state
| TSH in the range of 0.5-4.0 IU/mL
55
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
```
56
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
57
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
```
58
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
59
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.]
```
60
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]
61
Thyroid Suppressants
Avoid iodine ingestion [shellfish; kelp]
Drug interactions – Digoxin, anticoagulants
Can use β blockers for symptom control only
62
Adverse effects of thyroid suppressants
```
◦ Pruritic
maculopapular rashes, arthralgia, & fever
◦ Leukopenia
◦ Hepatotoxicity
◦ Agranulocytosis
◦ Hypothyroidism
```
63
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
```
