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Treatment of Hyperthyroidism
Following Pregnancy
AH is a 21 y/o white woman who
presented with a chief complaint of chest pain. She had been
previously diagnosed with hyperthyroidism. Upon admission, she had
complaints of constant left sided chest pain that radiated to her
left arm. She had been experiencing palpitations and tachycardia.
She had no diaphoresis, no nausea, vomiting, or dyspnea.
She had a
significant TSH of 0.004 and a free T4 of 19.3. Normal ranges for
TSH and free T4 are 0.5-4.7 µIU/mL and 0.8-1.8 ng/dL, respectively.
Her symptoms started four months into her pregnancy as tremors, hot
flashes, agitation, and emotional inconsistency. She gained 16
pounds during her pregnancy and has lost 80 pounds afterwards. She
complained of sweating, but has experienced no diarrhea and no
change in appetite. She was given isosorbide mononitrate and IV
steroids in the ER.
Family History: Diabetes, Hypertension, Father had a Coronary
Artery Bypass Graph (CABG) at age 34
Social History: She had a baby five months ago. She smokes a half
pack a day. She denies alcohol and drug use.
Medications: Citalopram 10mg once daily for depression; low dose
tramadol PRN pain
Physical Examination: Temperature 98.4; Pulse 123; Respiratory Rate
16; Blood Pressure 143/74
HEENT: She has exophthalmos and could not close her lids completely.
CARDIOVASCULAR: tachycardia.
NEUROLOGIC: She had mild hyperreflexiveness.
Lab: All labs within normal limits with the exception of
Sodium 133, Creatinine 0.2, TSH 0.004, Free T4 19.3
EKG showed sinus tachycardia with a rate of 122.
Urine pregnancy test was negative.
Hospital course:
After admission, she was given propranolol at 40mg daily and
continued on telemetry.
On the 2nd day of treatment, the patient still complained of chest
pain. EKG again showed tachycardia. Propranolol was increased from
40mg daily to 60mg twice daily.
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A I-123 thyroid uptake scan demonstrated an increased
thyroid uptake of 90% at 4 hours and 94% at 24
hours. The normal range for 4-hour uptake is 5-15% and 15-25% for
24-hour uptake. Endocrine consult recommended radioactive I-131 for
treatment of Graves disease.
Two days later she received 15.5mCi of I-131. She was to return home
after the iodine treatment. She was instructed to avoid contact with
her baby for the next week and to cease breast feeding.
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Assessment / Plan
1) Treatment of hyperthyroidism. Patient underwent radioactive
iodine 131 ablation therapy.
2) Management of cardiac symptoms stemming from hyperthyroidism.
Patient was discharged on propranolol 60mg, one tablet twice daily.
2) Monitor patient for complications of I-131 therapy such as
hypothyroidism. She should return to Endocrine Clinic in six weeks
to have thyroid function tests performed. Long-term follow-up
includes thyroid function tests at 6-12 month intervals.
3) Prevention of pregnancy for one year post I-131 therapy. Patient
was instructed to use 2 forms of birth control and was discharged an oral contraceptive, taken one tablet daily.
4) Monitor ocular health. Patient was given methylcellulose
ophthalmic, one drop in each eye daily. She should follow up in 6
weeks with the Ophthalmology clinic.
5) Management of depression. Patient will be continued on citalopram
10 mg.
*TEACHING NOTE*
Although surgery and radioactive iodine are contraindicated in
pregnancy, pregnant women with hyperthyroidism must be treated to
avoid fetal complications or death. Propylthiouracil is the drug of
choice for hyperthyroidism in pregnancy because it does not cross
the placenta as easily as methimazole. To avoid fetal hypothyroidism
and goiter, the lowest possible dose should be used.
BACK
© 2006 Nuclear Education Online
- Case submitted by Lynette Chastain, UAMS
May 2006 PharmD Candidate
- Images courtesy of University
of Arkansas for Medical Sciences Dept of Nuclear Medicine.
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