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Hyperthyroidism — back to basics
Simple truths matter in clinical practice.
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A 24-year-old Asian woman presented for an initial evaluation of hyperthyroidism. She had noticed a brief headache one week prior to seeing me.
A coworker at her office who was also moonlighting at a urology lab encouraged her to have labs checked. A thyroid-stimulating hormone test performed by that colleague came back low.
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The patient denied heat or cold intolerance, constipation, diarrhea, edema, hair loss, anxiousness, excessive energy or libido, tremulousness, irregular menses, dysphagia, thyroid tenderness, ophthalmologic symptoms, palpitations or sweating. She did report semi-intentional weight loss of 8 lb over past year, with normal appetite and morning fatigue.
The patient did not take any medications or nutritional supplements. Pertinent labs showed a TSH of 0.008 at the urology lab. Family history was negative for thyroid or other hormonal abnormalities. The patient did not smoke or drink alcohol or use recreational drugs and worked as an office manager. Vitals by the medical assistant showed a blood pressure of 114 mm Hg/70 mm Hg, pulse 68, height 5’ 5”, weight 135 lb.
Pertinent exam showed that the thyroid gland was positive for a bruit and enlarged to two to three times its normal size. It was soft and non-tender. Constitutional: no acute distress, well developed/well nourished. Her eyes were unremarkable; there was no lid lag.
Exam with exophthalmometer was unremarkable for a young Asian woman. Cardiovascular evaluation showed normal s1, s2, regular rhythm, no murmurs, no rubs and no gallops. Respiratory evaluation showed clear to auscultation bilaterally. She had no peripheral edema and no erythema/tenderness. Her neurologic exam showed she was alert, awake and oriented times three (AA&O x 3), deep tendon reflexes (DTRs) not increased and no tremor, normal strength.
In addition to ordering thyroid function tests at your own lab, which of these options would be the next best step in helping this patient?
A. Reassurance and reevaluation in six months.
B. Repeat measurement of vital signs by physician.
C. Prescription for methimazole, 40 mg daily.
D. Thyroid ultrasound.
E. Referral for thyroid surgery.
CASE DISCUSSION:
This is a young woman who presented with a goiter and what appeared to be very mild, gradual intentional weight-loss, normal BMI and a suppressed TSH from a dubious source. Hyperthyroidism must be the first diagnosis that comes to mind.
An ultrasound of the goiter might show enlarged blood vessels, but it would not necessarily imply over- or underproduction of thyroid hormone and would not define the underlying pathology (option D). Similarly, before a patient is treated with methimazole (option C) or referred for thyroid surgery (option E), which is a common treatment modality for Graves’ disease in Europe, the actual cause should be elucidated — it would be wrong to treat her if she were euthyroid, or to operate on her if she had thyroiditis.
On the other hand, just giving reassurance and reevaluating the patient in a few months (option A) may underestimate the actual severity of this patient’s condition. The most important task at hand is to prevent “badness,” in this case cardiovascular complications from potential hyperthyroidism. I found it odd that this patient was supposed to have a heart rate in the 60s. I remeasured (at rest, with a calm patient), and it was 116 bpm. I remeasured again (this time after the patient had gotten off the exam table), and it was 132 bpm. Throughout the remainder of the interview, the patient’s heart rate never fell below 100 bpm. My first action therefore, even before drawing thyroid function tests, was to prescribe a beta-blocker and to instruct the patient how to measure her own heart rate.
The moral is that one should verify vitals, especially in conditions where they play a critical role (answer B). Interestingly, she had levels for free T4, total T3 and TSH-receptor antibodies that were “off the charts,” ie, greater than the reported range for our lab and a thyroid uptake of 70%. She is currently doing much better on methimazole and atenolol. As for her moonlighting colleague, he has returned to doing PSA levels at night.
Ronald Tamler, MD, PhD, MBA, is an Assistant Professor in the Division of Endocrinology at Mount Sinai School of Medicine, N.Y.