Table 4.
Response to warfarin after levothyroxine initiation.
| Days since levothyroxine initiation | Warfarin dose (mg/day)a |
INRb,c | New warfarina dose (mg/day) |
Levothyroxine (75 mcg/day) |
TSHd
(μIU/mL) |
Free T4
e
(ng/dL) |
Free T3
f
(pg/mL) |
|---|---|---|---|---|---|---|---|
| 1 | 5: MTWThSSu 7.5: F |
3.2 | No change | Not taking | |||
|
| |||||||
| 13 | 5: MTWThSSu 7.5: F |
2.2 | No change | Taking since last visit | 3.63 | 0.7 | |
|
| |||||||
| 73 | 5: MTWThSSu 7.5: F |
1.5 | No change | Not taking for 2 weeks | <0.006 | 1.49 | |
|
| |||||||
| 86 | 5: MTWThSSu 7.5: F |
2.8 | No change | Only taking for 1week | <0.006 | 2.11 | 4.9 |
|
| |||||||
| 133 | 5: MTWThSSu 7.5: F |
2.5 | No change | Had not taken since last visit | 0.008 | 1.40 | 4.2 |
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 thyroxine, reference range 0.82–1.77.
fFree T3: free triiodothyronine, reference range 2–4.4.