What is the preferred thyroid management for a woman aged 34 years who presents with an enlarged thyroid, no nodules and irregular menstrual periods for the past six months?
The patient’s thyroid-stimulating hormone (TSH) was slightly elevated, thyroxine (T4) was within normal limits, thyroid ultrasound was normal and prolactin level was normal. Complete blood count revealed slight iron-deficiency anemia and an occult stool test was negative. I plan to start her on a low-dose birth-control pill and iron sulfate to control the bleeding and alleviate the anemia, but I am not sure what to do about her thyroid. — Margaret DeMarco, RNC, WHNP, Odessa, Tex.
It looks like this patient has subclinical hypothyroidism (as evidenced by slightly elevated TSH and normal free T4). Checking thyroid antibodies might help determine whether she has any further predisposition to thyroid disease (e.g., family history of thyroid disorders or personal history of autoimmune problems). Hashimoto’s thyroiditis is something else to consider. Subclinical hypothyroidism would not cause the change in her menstrual pattern.
Individuals with subclinical hypothyroidism have a 3% to 20% increased risk of going on to develop overt hypothyroidism, especially if goiter and thyroid antibodies are present. There is some debate over whether to treat patients with subclinical hypothyroidism with thyroid hormone.
The American Association of Clinical Endocrinologists recommends treatment with a low dose of levothyroxine (25 to 50 µg) for those with TSH levels between 5 and 10 µIU/mL who also have a goiter and positive thyroid antibodies; the goal is to get TSH to 0.3 to 3.0 µIU/mL (Endocr Pract. 2002;8:457-469). If TSH <5 µIU/mL, recheck thyroid labs in six months to look at trends.
Does your patient have a history of oligomenorrhea, or is this a new change in menstrual pattern? Does she have any signs of hyperandrogenism, such as hirsutism or persistent acne? Chronic oligomenorrhea (sometimes accompanied by dysfunctional uterine bleeding) paired with hyperandrogenism would suggest polycystic ovary syndrome. This would not change your approach but would prompt patient education about the ramifications of this diagnosis, along with higher suspicion for diabetes risk. — Kathy Pereira, MSN, FNP-BC, assistant professor, co-coordinator, Family Nurse Practitioner program, Duke University School of Nursing, Durham, N.C. (159-1)