| TNR | tonic neck reflex; true negative rate |
|---|---|
| TTR | transthoracic resistance; transthyretin; triceps tendon reflex |
| TVR | tonic vibratory reflex; total vascular resistance; tricuspid valve replacement |
| UR | unconditioned reflex; upper respiratory; uridine; urinal; urology; utilization review |
| VOR | vestibulo-ocular reflex; volume of regret |