A 42-year-old woman presents to her physician with heat intolerance and tachycardia. She complains of episodes of crying and depression. Further complaints consist of excessive lacrimation, decreased vision, and a sandy sensation in her eyes. Her medical history shows that she is epileptic and is currently taking Dilantin. The physical exam showed an enlarged thyroid, exophthalmos, and pretibial myxedema.
The following laboratory tests were performed:
Total T4 = 14.2 mg/dl (5.5 - 11.0) THBR (Thyroid hormone binding ratio) = 1.23 (0.80-1.04)
1. What additional laboratory determinations would be of value in determining whether the Dilantin therapy was interfering with the results?
2. Calculate the Free Thyroxine Index (FT4I) (Reference Range= 4.2-13.0 mg/dl). Does this indicate that the Dilantin is interfering with the thyroid test? Why or why not?
3. What thyroid antibodies would we expect to be positive for this patient?
4. What would be the most probable diagnosis?
5. What results would you expect for the following analytes:
Creatine Kinase (CK)
Alkaline Phosphatase (ALP)
Calcium
Cholesterol
Glucose