A 50-year -old female was found to have abnormal thyroid function on routine blood testing. Her TSH level is 9 ~U/ml (0.35 to 5.0 ~U/ml is normal) and free T 4 is 1.3 ng/dl (normal 0.8 to 1.8 ng/dl). She is currently asymptomatic and is taking no medications. She denies use of tobacco, alcohol, and drugs. Family history is positive for a mother with hypothyroidism. She has four siblings, all are alive and well. Her menstrual cycles are regular. Examination is unremarkable. Her CBC, serum chemistries, and lipid profile are within normal limits. Which of the following will be most useful in guiding her therapy?
- A. T3 measurement [31%] .,
- B. Antithyroid peroxidase (anti-TPO) measurement [35%]
- C. Thyroid ultrasound [6%]
- D. Radioactive iodine uptake and scan [1 3%]
- E. Thyroglobulin measurement [14%]
The patient has subclinical hypothyroidism, which is defined as a mild elevation in TSH levels (5 to 1 0) accompanied by normal free T41evels. Treatment is warranted in the presence of (1) antithyroid antibodies, (2) an abnormal lipid profile, (3) symptoms of hypothyroidism, and (4) ovulatory and menstrual dysfunction. When antithyroid antibodies are present with elevated TSH, there is a high chance for a patient to become overtly hypothyroid. A patient with a TSH level > 10 ~U/ml is also generally treated with levothyroxine. However, the downside of the treatment in asymptomatic patients is the risk of overtreatment, leading to increased bone loss and atrial fibrillation. Routine screening of thyroid functions is controversial. The American Thyroid Association (ATA) recommends all individuals over the age of 40 to be screened for thyroid dysfunction. The American College of Physicians recommends screening women over 50 years with findings suggestive of thyroid disease.
(Choices A, 0, and E) T3 measurement, radioactive iodine uptake, and thyroglobulin measurement play no role in the management of subclinical hypothyroidism.
(Choice C) Thyroid ultrasound could be useful if thyroid enlargement is present, in order to monitor any change in size and look for dominant nodules (> 1 em in diameter). The patient’s physical exam is normal; therefore, thyroid ultrasound in the above case will not help in making management decisions.
Educational Objective: Asymptomatic subclinical hypothyroidism does not require treatment. Treatment is warranted in the presence of:
1 . antithyroid antibodies 2. an abnormal lipid profile 3. symptoms of hypothyroidism 4. ovulatory and menstrual dysfunction