A 26-year-old woman with previously well-controlled primary hypothyroidism had been an in patient for treatment of an eating disorder for the previous 6 weeks. She had a history of anaemia resulting from multiple vitamin deficiency and gastric erosions. She had been taking levothyroxine 125 micrograms daily for the previous 5 years; since admission her medication had also included ferrous sulfate, calcium and vitamin D, and sucralfate. Her daily medicines were taken under supervision at 09.00 h. Although she was eating better and had gained 4 kg in weight, she was now complaining of tiredness and feeling "worse than ever".
On examination, she was thin, slightly pale and had no palpable goitre. Recent blood tests had confirmed that her anaemia had resolved.
Investigations:
serum corrected calcium2.28 mmo/L (2.20-2.60)
serum thryoid-stimulating hormone12.0 mU/L (0.4-5.0)
serum free T48.0 pmol/L (10.0-22.0)
serum T30.90 nmol/L (1.07-3.18)
What is the most appropriate next step in management?
A . add liothyronine 20 micrograms daily
B . administer levothyroxine alone at bedtime
C . increase levothyroxine to 175 micrograms daily
D . no change in treatment
E . stop treatment with calcium and vitamin D
Answer: B
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