Graves’ Disease and Treatment Effects on Warfarin Anticoagulation

Table 2

Outpatient warfarin response to the addition of methimazole.

Day of methimazole	Warfarin dose; (mg/day)^a	INR^b,c	New warfarin^a dose; (mg/day)	Methimazole; (mg/day)	TSH^d; (𝜇IU/mL)	Free T4^e; (ng/dL)
1	Held	2.8	1	10
4	Patient withheld	1.3	Restart 1 mg	10	<0.005	4.69
12	1	1.1	2	10
21	2	1.2	3	10	<0.005	1.34
28	3	1.5	4	10	<0.005	1.14
35	4	1.7	5	10
45	5	2	5	10	<0.005	0.83
63	5	1.6	5: MTWRSSu; 7.5: F	10
81	5: MTWRSSu; 7.5: F; (missed 1 dose)	1.2	5: TRSSu; 7.5: MWF	10	0.007	1.06
112	5: MTWRSSu; 7.5: F	1.9	5: TWRSSu; 7.5: MF	10	<0.005	0.65
120	Radioactive iodine^131 ablation

aLetters are abbreviations for days of the week: Monday (M), Tuesday (T), Wednesday (W), Thursday (R), Friday (F), Saturday (S), and Sunday (Su).
^bINR: international normalized ratio, goals 2-3.
^cINR obtained via point of care testing with Roche Diagnostics CoaguChek XS.
^dTSH: thyroid stimulating hormone, reference range 0.450–4.500.
^eFree T₄: free triiodothyronine, reference range 0.82–1.77.