Case Study 1 – Thyroid Function

Case 1
(See Thyroid Function Panel Reference Range below)

Review the following case and answer the questions.

Ms. Jefferson is a 50-year-old woman who comes into the clinic to review her laboratory results from 2 weeks prior. She is in good health and has no complaints.
Her laboratory values are normal except for the following:
• TSH = 30 mU/L; T4 = 3.0 mcg/dL
• free T4 = 0.5 mcg/dL
• free thyroxine index = 3.0
• T3 = 90 ng/dL

Answer the following questions.
1. Based on these lab findings Ms. Jefferson is diagnosed with which thyroid disorder?
o Hyperthyroidism
o Subclinical hyperthyroidism
o Hypothyroidism
o Subclinical hypothyroidism
o The lack of symptoms in the type of thyroid disorder Ms. Jefferson has is uncommon.

2. The lack of symptoms in the type of thyroid disorder Ms. Jefferson has is uncommon. True or False

3. Ms. Jefferson’s thyroid disorder is most likely caused by what?
o A pituitary adenoma (i.e., thyrotroph)
o Chronic autoimmune thyroiditis (i.e., Hashimoto thyroiditis)
o Autoimmune Graves disease
o Iodine deficiency

4. Ms. Jefferson asks when she should return to evaluate her thyroid disorder. You should respond:
o An annual evaluation should be sufficient.
o Return to have a TSH level done 6 weeks after starting therapy.
o Six months from now.
5. Ms. Jefferson asks what are some possible symptoms of her thyroid disorder? Indicate all that apply.
o Weight gain
o Diarrhea
o Anxiety
o Palpitations
o Fatigue
o Cold intolerance

Thyroid Function Panel Reference Range

Test Reference range*

TSH 0.450–4.500 mU/mL
Thyroxine (T4), total 4.6–12.0 mcg/dL
Thyroxine (T4), free (direct) 0.7–1.9 mcg/dL
Free thyroxine index (calculated) 4–11
Triiodothyronine (T3), total 80–180 ng/dL

* Reference range may vary from one laboratory to another.