Thyroid Disorders Flashcards
(100 cards)
1
Q
What are two antibodies to look for that indicate that the hypothyroidism is due to chronic autoimmune thyroiditis?
A
Antithyroid peroxidase (TPO) Antithyroglobulin (ATgA)
2
Q
What are some drugs that can interfere with the TSH test?
A
Corticosteroids Dopamine Metoclopramide Metformin Amiodarone Thyroid Hormone
3
Q
What is the #1 way to screen for a thyroid disorder?
A
Get TSH level
4
Q
What is a normal TSH level?
A
0.4-4.0 microunits/mL
5
Q
When is an RAIU test appropriate?
A
when you need to determine a RAI dose for a patient with Grave’s Disease
6
Q
Clinical Presentation of Hypothyroidism?
A
Subjective: • fatigue • cold (hypothermia) • depression/ memory loss • dry skin • wt gain • GI: constipation • menstrual irregularity • muscle aches/weakness
Objective: • wt gain • bradycardia • goiter • hyperlipidemia
7
Q
In primary hypothyroidism, where does the pathology originate?
A
the thyroid gland
8
Q
In secondary hypothyroidism, where does the pathology originate?
A
the anterior pituitary or hypothalamus
9
Q
Etiology of Hypothyroidism?
A
- Hashimoto’s Disease (autoimmune)
- Iatrogenic
• treating hyperthyroidism (RAI, surgery)
• medications
• iodine (deficiency and excess can both cause hypothyroidism)
10
Q
What are some medications that can cause hypothyroidism?
A
"ITALIC" Interferon-alfa Tyrosine Kinase Inhibitors Amiodarone Lithium Interleukin-2 ClO4-
*self study
11
Q
How do you resolve hyperthyroidism if it is caused by amiodarone? Is the onset slow or fast?
A
Fast onset, resolve by D’C amiodarone
12
Q
How can you tell the difference between primary and secondary hypothyroidism based just on lab values?
A
Primary: HIGH TSH
Secondary: normal to low TSH
13
Q
What is the most common form of hypothyroidism in the US?
A
Hashimoto’s
14
Q
How do you resolve hypothyroidism if it is caused by amiodarone? Is the onset slow or fast?
A
SLOW onset
keep the amiodarone and add TH replacement therapy
15
Q
If a pt has hypothyroidism and is also on a CNS depressant, how should you monitor or adjust the dose?
A
DECREASE the CNS depressant dose (as the patient returns to a euthyroid state, you can begin to increase the dose back to normal to maintain efficacy)
16
Q
If a pt has hypothyroidism and is also on digoxin, how should you monitor or adjust the dose?
A
DECREASE the dose (b/c in hypothyroidism dig has a decreased Vd and Cl and there is an increased risk of toxicity)
17
Q
If a pt has hypothyroidism and is also on warfarin, how should you monitor or adjust the dose?
A
INCREASE the dose (b/c in hypothyroidism, the CF are cleared slower, which decreases the efficacy of warfarin)
18
Q
When your patient is on warfarin and is hypothyroid, will they be more likely to clot or bleed?
A
clot
19
Q
If a pt has hypothyroidism and is also on insulin, how should you monitor or adjust the dose?
A
DECREASE the dose (insulin remains in the body longer in pts with hypothyroidism)
20
Q
What is the half-life of Levothyroxine?
A
7 days
21
Q
What is the oral BA of Levothyroxine?
A
80%
22
Q
When might you use liothyronie?
A
Myxedema coma
23
Q
What are some cons of using Armour Thyroid or NP Thyroid?
A
inconsistent amounts of TH
allergic response (porcine)
High T3:T4 ratio
24
Q
What are some cons of using levothyroxine?
A
narrow therapeutic window (do not change brand to generic if possible)
decreased BA with food
25
What are some counseling points to consider with levothyroxine?
take one hour before breakfast on an empty stomach
26
What is the standard dose for levothyroxine in "normal" pts?
1.6 mg/kg/day
27
How do you dose for levothyroxine in high risk patients? Who is considered high risk?
```
start with a LOWER dose than 1.6 mg/kg/day (usually the initial dose is 25 mcg/day)
High Risk:
• cardiac disease (MI, HF, arrhythmias)
• elderly ( ≥ 65 yo)
• longstanding hypothyroidism
```
28
What pregnancy category is levothyroxine?
A (Use it!)
29
What are some considerations for pts who are pregnant and have hypothyroidism? Make sure to explain the following:
1. screening
2. treatment
3. monitoring
Screening: screen pregnant women before or during their 1st trimester for hypothyroidism
Treatment: pt may need a HIGHER dose than normal
• treat pts even if they have asymptomatic, subclinical or mild hypothyroidism
Monitoring: q 6 weeks during pregnancy
30
How do you calculate the levothyroxine dose in pts who have to have IV levothyroxine?
PO --> IV (half the dose)
IV --> PO (double the dose)
ex. a pt on 100 mcg of levothyroxine PO should be on 50 mcg levothyroxine IV
31
What are some drugs that can decrease the BA/absorption of levothyroxine?
* BAS: cholestyramine
* GI: Antacids, H2-blockers, PPIs, sucralfate
* dietary fiber supplements
* Iron supplements
32
What are some drugs that increase the clearance of levothyroxine (inducers)?
1. rifampin
2. phenytoin
3. phenobarb
4. carbamazepine
5. sertraline
33
Clinical Presentation of Myxedema Coma?
```
AMS
hypothermia
delayed DTRs
hypoxia/CO2 retention
severe hypoglycemia
hyponatremia
paranoid psychosis
delirium --> coma
```
34
Signs of Myxedema Coma?
```
large tongue
yellowish skin
thin hair
cardiomegaly
bradycardia
```
35
What are some triggers of myxedema coma?
1. cold weather/ hypothermia
2. stress: surgery, trauma, infection
3. Comorbities:
• DM
• MI
• hypoglycemia
• fluid/electrolyte imbalance
4. respiratory depressants (narcotics, sedatives)
5. diuretics
36
What is the mortality rate of myxedema coma?
60-70%
37
What is the appropriate dosing of TH for a pt with myxedema coma?
1st, give a LD of levothyroxine 300-500 mcg IV.
Then start a MD of levothyroxine 75-100 mcg IV QD x 1-2 days
if the pt is unresponsive, add T3:
LD: T3 24-40 mcg IV
MD: T3 10 mcg IV q 6-8 h
38
What is the most common cause of HYPERthyroidism?
Grave's Disease
39
Clinical Presentation of HYPERthyroidism:
* heat intolerance
* wt loss
* palpitations, DOE
* foot edema
* GI: diarrhea
* amenorrhea, impaired fertility
* tremor
* weakness and fatigue
* nervousness, irritability
* insomnia
40
What are some physical signs of hyperthyroidism?
```
thinning hair
bulging eyes
"plummer's nails"
flushed, warm skin
redness of palms
brisk DTRs
tachycardia
osteoporosis (in prolonged hyperthyroidism)
```
41
[SATA] Which of the following are patients who may be chosen for surgery treatment of hyperthyroidism?
A. Elderly
B. Cancer
C. esophageal obstruction or respiratory difficulty due to large goiter
D. CI to thioamide or RAI
E. children
B. cancer
C. esophageal obstruction or respiratory difficulty due to large goiter
D. CI to thioamide or RAI
42
What are thioamides?
anti-thyroid drugs: PTU and methimazole
43
When are thioamides preferred?
Children
Pregnancy
Uncomplicated disease
44
Which thioamide can you use in children?
only methimazole
45
Which thioamide can you use in pregnancy?
only PTU
| b/c methimazole causes fetal development defects
46
You can also give thioamides before treating the patient with RAI or surgery. WHY?
to deplete the hormone concentration in the gland to decrease the risk of thyrotoxicosis
D'C thioamide 2-3 days before RAI and restart after 3-7 days
47
What is the treatment goal of thioamides?
to reach a euthyroid state within 8 weeks
48
How long should you treat with thioamides?
the duration is unclear, but generally, pts are treated for 102 years
49
What is the remission rate of pts with hyperthyroidism after 1-2 years of therapy with thioamides?
60%
50
MOA of methimazole:
inhibits TH synthesis
51
MOA of PTU:
inhibits TH synthesis and blocks peripheral conversion of T4 --> T3
52
ROA of methimazole and PTU:
orally
| rectally
53
dosing of methimazole?
Start with 30-40 mg daily (or q 12 h) x 6-8 weeks
| then, give a MD of 5-10 mg daily x 12-18 months
54
Why is methimazole the thiamide of choice in most patients?
daily dosing
55
When is methimazole NOT the drug of choice?
pregnancy, breastfeeding, thyroid storm
56
ADRs of methimazole?
"Fred the ALPACA did not like methimazole because it gave him:"
```
Fever
Arthralgia, arthritis
Lupus-like syndrome
Pruritis, rash, urticaria
Abnormal taste
Cholestatic jaundice
Agranulocytosis (rare)
```
57
Dosing of PTU?
Start with 100-200 mg q 6-8 h x 6-8 weeks
| then give a MD of 50 mg BID-TID x 12-18 months
58
When is PTU the drug of choice?
pregnancy, breastfeeding, thyroid storm
59
ADRs of PTU?
Fred the ALPACA really doesn't like PTU because it also gave him liver damage due to:
increase in LFTs
hepatitis
AND
```
Fever
Arthralgia, arthritis
Lupus-like syndrome
Pruritis, rash, urticaria
Abnormal taste
Cholestatic jaundice
Agranulocytosis (rare)
```
60
Why is PTU not preferred in peds?
BBW: severe liver injury and acute liver failure seen in PTU
61
How successful are thioamides? (What is the permanent remission rate?)
permanent remission
62
What are some factors that may make remission more likely in pts taking thioamides?
1. longer duration of thioamide tx
2. smaller goiters, (decrease in goiter size during tx)
3. mild symptoms
4. non-smokers
5. absence of bulging eyes
6. undetectable or low TRAb levels (antibodies)
63
What are some labs you need to monitor at baseline in pts with hyperthyroidism?
1. free T4
2. TSH
3. CBC with differential
4. LFTs (in PTU only)
64
When do you see the pt again for monitoring and labs?
4-6 weeks after initiation or change in dose
65
Once the patient has reached maintenance stage, when do you see the pt again for monitoring and labs?
q 3-6 months
66
What is Radioiodine Ablation (RAI)?
destruction of the gland with a radioactive isotope
67
What patients are preferred in RAI?
elderly, debilitated, older pts who are poor surgical candidates
pts who have failed drug tx or had ADRs
pts with recurrent hyperthyroidism after surgery
68
What treatment for hyperthyroidism is absolutely CI in pregnancy?
RAI
69
How long does it take for RAI to be effective?
6-18 weeks
| Some pts may need more than 1 treatment of RAI
70
What are some ADEs of RAI?
Hypothyroidism (80-90% of pts)
| Worsening ophthalmopathy
71
What meds should you not give before RAI?
Iodides (SSKIs) because they decrease the uptake of RAI
72
Why would you use thioamides or iodides after RAI?
To control symptoms until the RAI kicks in and kills the gland
73
How long should you wait between RAI treatments?
3-6 months
74
A subtotal thyroidectomy is about ____ % effective.
90%
75
When would you use iodides in patients with hyperthyroidism?
Preoperatively (before surgery)
Thyroid storm (give them all we've got)
Symptom relief
76
What is the MOA of iodides?
Block T3 and T4 release
77
Why would you use iodides before surgery?
To decrease gland vascularity and increased firmness of the gland
78
What are 2 iodides?
1. SSKIs ( Strong Solution of K+ Iodide)
| 2. Lugol's drops
79
What is the dose of SSKI or Lugol's drops for pts before surgery?
5-10 drops po TID x 10-14 days before surgery
Lugol's is 8 mg/drop
SSKI is 59 mg/drop
80
__________ can be used AFTER RAI in pts allergic to thioamides or to prevent recurrent hyperthyroidism
Iodides
81
What are some adverse effects of iodides?
```
Hypersensitivity
Rash
Ulceration of mucous membranes
Metallic taste
Salivary gland swelling
```
82
What are some pros of iodides?
Simple
Low cost
No gland destruction
83
What are the cons of iodides?
Relapse
Allergic reactions
Cannot is before RAI (b/c they decrease RAI uptake)
Potentilla med errors (dosed in drops instead of mLs)
84
Why would you give a patient a BB when they have hyperthyroidism?
To block the peripheral thyroid hormone effects (nervousness, palpitations, diaphoresis, heat intolerance, tremor)
85
When do you give a pt with hyperthyroidism a BB?
Thyroid storm
Prep for surgery
Short term during pregnancy
86
What is the dose of propranolol to give to pts with hyperthyroidism?
Propranolol 10-40 mg po q 6 h ( or prn)
87
Why is propranolol a the gold standard BB to use in pts with hyperthyroidism?
No ISA
| Blocks some peripheral T4 --> T3 conversion
88
What is thyroid storm?
When the body can't compensate for hyperthyroidism
Exacerbation of thyrotoxicosis (medical emergency)
89
What are some triggers of thyroid storm?
```
Infection
Trauma
D'C of meds
Stress
DKA
Pregnancy
MI, CVA
Drug-induced
```
90
Clinical presentation of thyroid storm:
```
Tachycardia and A fib
HF, cardiogenic shock
Acute onset of high fever ( > 103)
Agitation, delirium, psychosis
Stupor, coma
Severe N/V/D
Liver enlargement, jaundice (poor prognosis)
```
91
How do you treat thyroid storm?
"Give 'em all you've got"
• Supportive care: fluids, oxygen, cooling blanket, APAP, antibiotics if needed
• Propranolol 1 mg/min IV push until HR 90-110
--MD: 5-10 mg/h IV or 40 mg PO q 6 h
• PTU 200 mg PO q 6 h (or rectal)
-- preferred over methimazole because PTU has a rapid onset
• Lugol's 10 gtts PO TID, 1 hour after PTU
• Hydrocortisone 100 mg IV q 8 h (acutely depress T3 levels
92
Which type of thyroid disorder presents with constipation? What about diarrhea?
Constipation: hypothyroidism
Diarrhea: hyperthyroidism
93
According to the ATA: When do you begin screening patients for thyroid disorders?
Once the patient is older than 35 yo and then every 5 years after that.
94
What are some specific patient considerations for when you might screen a patient for thyroid disease regardless of age?
T1DM (~10% can develop autoimmune diseases such as Hashimoto's or Graves)
Pernicious anemia
Abnormal thyroid gland
Psychiatric disorders such as depression (may be caused by low TH)
Amiodarone/lithium therapy
95
When would you treat a patient with subclinical hypothyroidism?
If their TSH is b/w 5-10 micro-units/mL AND they have one of the following:
• symptoms
• antibody titers (anti-TPO / ATgA)
• PREGNANCY
96
What is considered "overt" hypothyroidism?
The patient has the disease:
TSH > 10 micro-units/mL
Low T4
Evidence of clinical features (symptomatic)
97
What are some cases where you may need to increase a patient's levothyroxine dose?
Pregnancy
If on an inducer (phenytoin, phenobarbital, carbamazepine, sertraline, rifampin)
On an OCP or HRT containing estrogen
98
Adverse effects of levothyroxine?
Rare unless dosed incorrectly:
Cardiac—HF, MI, arrhythmias
Skeletal—osteoporosis in post-menopausal women
99
How do you titrate levothyroxine?
Can change the dose every 4-6 weeks by 25 mcg
100
How often do you monitor a patient on levothyroxine?
Every 4-6 weeks until target reached, then every 6 months
Can check annually once patient reaches and maintains a euthyroid state
Monitor adherence!! (Especially in patients taking > 200 mcg with elevated TSH)
