Graves' Disease/Hyperparathyroidism Flashcards
Graves’ Disease therapy options
Antithyroid drug
Radioactive iodine
Thyroidectomy
Factors favoring an option for antithyroid drug
Mild disease Increased surgical risk Limited life expectancy Moderate-severe GO No surgeon access Previous neck operation/irradiation
CIs to ATD
Previous known allergic reaction
Patient preference factors for ATD
High value on avoidance of lifelong LT4 therapy, exposure to radioactivity, and surgery
Low value on need for monitoring and possible relapse
Thioamides use
For Graves’ disease and to get patients chemically euthyroid before RAI/thyroidectomy
Will thioamides cure Graves’?
NO
Methimazole (MMI)
~10 times as potent as PTU
Preferred thioamide
MMI dosing
Depends on FT4:
1-1.5x ULN: 5-10mg QD
1.5-2x-ULN: 10-20mg/day QD or BID
2-3x-ULN: 30-40mg/day BID
MMI ADEs
Agranulocytosis, aplastic anemia, exfoliative dermatitis, hepatitis, abdominal pain, dark urine, jaundice, acholic stools
Most common are fatigue and rash
MMI baseline labs
CBC with diff
MMI monitoring
Leukopenia, pruritic rash, arthalgia
MMI treatment algorithm
- Consider CBC and liver panel to establish baseline values
- Start MMI and dose on FT4 level
- Check FT4, T3 levels in 2-6 weeks
4a. If patient isn’t euthyroid, continue therapy at the MD (30-50% reduction from initial dose)
4b. If patient IS euthyroid, taper dose down by 30-50% over a few weeks and repeat thyroid panel in 4-6 weeks
5a. If patient isn’t euthyroid after that, increase dose slightly by 5-10mg/day and repeat the thyroid panel in 4-6 weeks
5b. If patient IS euthyroid, continue therapy for 12-18 months and monitor thyroid labs every 2-3 months - Consider stopping MMi if TSH and TRAb levels are normal after 12-18 months of therapy
Propylthiouracil (PTU)
Drug of choice in thyroid storm and 1st trimester of pregnancy
Factors favoring an option for radioactive drug
Increased surgical risk, planning pregnancy >6 months out, CIs to ATD use, no surgeon access, previous neck operation/irradiation
CIs to radioactive drug
Pregnancy, lactation, suspected or known cancer, unable to meet safety guidelines, informed caution for pregnancy 4-6 months out
Patient preference factors for radioactive drug
High value on definitive control and avoidance of surgery
Low value on rapid cure, development of GO, and need for lifelong LT4 replacement
Radioactive iodine (Na 131I)
Used to render the patient hypothyroid
Radioactive iodine counseling points
Avoid high-iodine foods before treatment No contact with children for 5 days No contact with pregnant women for 10 days No more than 2 hours of contact at a time Bathroom etiquette Avoid bodily fluid contact for 4 days Flush things with bodily fluid contact Wash things separately
Radioactive iodine side effects
Transient hyperthyroidism, release of orbital antigen, thyroid tenderness, salivary gland tenderness/enlargement, dysphagia
Radioactive iodine CI
Pregnant/lactating
When do you use propranolol?
For symptomatic patients
Iodides
Potassium iodide (SSKI), Lugol’s solution
When are iodides used?
Surgery-prep drug, adjunct to RAI treatment
Iodides side effects
“Iodism”
Metallic taste, head cold, burning mouth/throat, sore teeth/gums, stomach upset, diarrhea
Hypersensitivity reactions, salivary gland swelling, gynecomastia
RAI treatment timeline: at diagnosis
Propranolol for symptoms
MMI in severe disease 3-7 days before the RAI dose
Females of childbearing potential do a pregnancy test before
RAI treatment timeline: after RAI dose
Start steroids (prednisone, 0.4-0.5 mg/kg/day) 1-3 days after RAI Start MMI PRN 3-7 days after RAI dose, taper weeks after RAI dose and D/C Taper steroids over 2 months and taper the propranolol if used
Post-RAI monitoring
Lab work q4-6 weeks that includes FT4, total T3, and TSH
Post-RAI treatment if successful
If successful, start IBW-based levothyroxine dosing
If hyperthyroidism persists after 6 months…
…suggest retreatment with radioactive iodine
Factors favoring thyroidectomy
Larger goiter, malignancy suspected, planning pregnancy <6 months out, moderate-severe GO, high TRAb levels
Thyroidectomy CIs
Substantial comorbidity, pregnancy, lack of access to high-volume surgeon
Patient preference factors for thyroidectomy
High value on prompt, definitive control and avoidance of exposure to radioactivity
Low value on surgical risk and need for lifelong LT4 replacement
Thyroidectomy complications
Transient or permanent hypocalcemia, hyperthyroidism can persist, vocal cord abnormalities
Thyroidectomy prep goal
Get patient euthyroid and stable before surgery
Thyroidectomy prep
Start MMI 6-8 weeks before surgery
Start iodide 10-14 days before surgery
Start beta-blocker 7-10 days before surgery
Consider normalizing calcium and vitamin D
What to do post-thyroidectomy
Obtain serum calcium, intact parathyroid hormone levels, wean beta-blocker, stop MMI, start levothyroxine
Drugs known to affect thyroid levels
Lithium and amiodarone
