Thyroid obstacle course: Many challenges from a single gland

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Figure 1
Thyroid ultrasonography images. (A) Transverse view of the right thyroid lobe showing a 4-mm nodule (blue arrow). (B) Transverse view of the left thyroid lobe showing a solid hypoechoic nodule that is taller-than-wide (see calipers and measurements).

TABLE 1

Initial laboratory results

Test	Result (reference range)^{^a}
White blood cell count	9.42 × 10⁹/L (4.0–11.0)
Hemoglobin	16.9 g/dL (12.1–17.2)
Hematocrit	49.2% (38–51)
Mean corpuscular volume	85.4 fL (80–100)
Platelet count	252 × 10⁹/L (130–400)
Sodium	141 mmol/L (137–145)
Potassium	4.0 mmol/L (3.5–5.0)
Chloride	106 mmol/L (98–107)
Carbon dioxide	25 mmol/L (24–34)
Urea nitrogen	15 mg/dL (8–26)
Creatinine	1.1 mg/dL (0.57–1.25)
Glucose	87 mg/dL (73–115)
Calcium	10.2 mg/dL (8.4–10.2)
Proteins, total	8.0 g/dL (6.0–8.3)
Albumin	4.5 g/dL (3.5–5.0)
Bilirubin, total	0.6 mg/dL (0.1–1.1)
Aspartate aminotransferase	23 U/L (12–50)
Alanine aminotransferase	46 U/L (21–72)
Alkaline phosphatase	72 U/L (40–150)
Thyroid-stimulating hormone	0.025 mIU/L (0.350–4.920)
Hemoglobin A1c	5.2% (4.2–5.8)

TABLE 2

Differential diagnosis of low thyroid-stimulating hormone level

Endogenous thyrotoxicosis due to single or multiple autonomously functioning or hot nodules and Graves disease

Thyroiditis, in which preformed hormone is released from an inflamed thyroid

Hypothalamic or pituitary disease (central hypothyroidism), resulting in low production of thyroid-stimulating hormone

Euthyroid sick syndrome (nonthyroidal illness)

Medication effects from glucocorticoids, exogenous thyroid hormone, lithium, amiodarone, and interferon

TABLE 3

Hyperthyroidism signs and symptoms

Common findings	Less-common findings
Palpitations, atrial fibrillation	Elevated alkaline phosphatase, elevated aminotransferases, or both
Weight loss, often despite increased appetite	Syncope or presyncope
Anxiety	Periodic paralysis
Heat intolerance	Thymus enlargement
Tremor	Normochromic normocytic anemia
Increased frequency of bowel movements	Pretibial myxedema
Shortness of breath
Lighter menstrual periods
Erectile dysfunction, decreased libido
Hair loss (scalp and lateral eyebrows)
Proptosis, lid lag, chemosis

TABLE 4

Summary of American Thyroid Association recommendations for treatment of subclinical hyperthyroidism

	Thyroid-stimulating hormone persistently < 0.10 mIU/L	Thyroid-stimulating hormone between 0.10 mIU/L and lower limit of normal
Any symptoms, age ≥ 65, cardiovascular disease, osteoporosis, postmenopausal and not on estrogen or osteoporosis treatment	Treatment is recommended	Consider treatment
None of the above	Consider treatment	Observation is recommended