A 29-year-old woman comes to the physician because of worsening fatigue for the past few months. She has also noticed dizziness, nausea, constipation, and hair loss. Her past medical history is unremarkable except for eclampsia with complicated vaginal delivery 1 year ago. She takes estrogen and progesterone-containing birth control pills. She has regular menstrual periods.
Her temperature is 36.1 C (97 F), blood pressure is 90/60 mm Hg, and pulse is 58/min. She weighs 50 kg (110.2 lb) and is 165 cm (5'5") tall. Her thyroid gland is normal in size on palpation. Her skin is dry and she has sparse axillary and pubic hair. Visual fields are normal on confrontation. The remainder of the examination is unremarkable.
Laboratory results are as follows:
Which of the following is the most appropriate next step in management of this patient?

Question

A 29-year-old woman comes to the physician because of worsening fatigue for the past few months.  She has also noticed dizziness, nausea, constipation, and hair loss.  Her past medical history is unremarkable except for eclampsia with complicated vaginal delivery 1 year ago.  She takes estrogen and progesterone-containing birth control pills.  She has regular menstrual periods.
Her temperature is 36.1 C (97 F), blood pressure is 90/60 mm Hg, and pulse is 58/min.  She weighs 50 kg (110.2 lb) and is 165 cm (5'5") tall.  Her thyroid gland is normal in size on palpation.  Her skin is dry and she has sparse axillary and pubic hair.  Visual fields are normal on confrontation.  The remainder of the examination is unremarkable.
Laboratory results are as follows:
 Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_97a9_38de_853d_b3ee88097979_MD0002_00 This patient's low TSH, low free T4, and clinical symptoms (e.g., fatigue, hair loss, etc) suggest central hypothyroidism. The normal total T4 is due to increased thyroid binding globulin from birth control pills. Causes of central hypothyroidism include pituitary adenomas (most common), pituitary surgery or radiation, infiltrative diseases (e.g., hemochromatosis), infarction (Sheehan's syndrome), or hypothalamic lesions. Patients typically present with features of hypothyroidism with evidence of other pituitary hormone deficiencies (e.g., ACTH, growth hormone, etc). ACTH stimulates the release of adrenal and ovarian androgens, which regulates pubic and axillary hair development in females. ACTH deficiency can lead to sparse pubic and axillary hair (as in this patient). The likely cause of this patient's central hypothyroidism is Sheehan's syndrome, a result of her complicated delivery. Severe Sheehan's can present within days after delivery with failure to lactate, lethargy, weight loss, and loss of sexual hair. Less severe Sheehan's syndrome can present months to years after delivery with milder symptoms. Hypothyroid symptoms may take a few weeks to appear due to the long circulating half-life of T4, but multi-hormonal deficiency is common. All patients with central hypothyroidism should undergo neuroimaging to evaluate for pituitary/hypothalamic masses and chemical testing for pituitary hormones (especially adrenal). Glucocorticoid deficiency must be diagnosed and treated in patients with central hypothyroidism before starting levothyroxine therapy. Patients with undiagnosed and untreated secondary insufficiency who are given levothyroxine can develop adrenal crisis (Choice D). Levothyroxine dosing is adjusted to the patient's symptoms and/or maintaining free T4 levels at the upper part of normal range. Other hormone deficiencies should also be concurrently treated. (Choice A) Anti-TPO antibodies are more useful in patients with subclinical primary hypothyroidism. However, TSH may be modestly elevated in some patients with central hypothyroidism due to overproduction of biologically inactive TSH. Measurement of anti-TPO may be helpful in these cases to differentiate from subclinical hypothyroidism and primary thyroid disease. (Choice C) This patient is taking an oral contraceptive pill, which is likely suppressing the FSH level and making it difficult to interpret. (Choice E) Radioactive iodine uptake (RAIU) would be useful in evaluating suspected thyrotoxicosis, which is not seen in this patient with hypothyroidism. Educational objective: Central hypothyroidism usually presents with hypothyroid symptoms, low TSH, and low T4 with evidence of other hormone deficiencies. Patients should undergo neuroimaging and pituitary hormone testing. Glucocorticoid deficiency must be diagnosed and treated in patients with central hypothyroidism before starting levothyroxine therapy. Levothyroxine given to patients with undiagnosed glucocorticoid deficiency can precipitate an adrenal crisis. __________ References: Central hypothyroidism (http://www.ncbi.nlm.nih.gov/pubmed/21966662) Sheehan's syndrome (http://www.ncbi.nlm.nih.gov/pubmed/15237929)

A 29-Year-Old Woman Comes to the Physician Because of Worsening