R right
RA rheumatoid arthritis or right atrium
RAD right atrial axis deviation
RAE right atrial enlargement
RAP right atrial pressure
RBBB right bundle branch block
RBC red blood cell
RBP retinol-binding protein
RDA recommended daily allowance
RDW red cell distribution width
RIA radioimmunoassay
RIH right inguinal hernia
RLL right lower lobe
RLQ right lower quadrant
RML right middle lobe
RNA ribonucleic acid
R/O rule out
ROM range of motion
ROS review of systems
RPG retrograde pyelogram
RRR regular rate and rhythm
RTA renal tubular acidosis
RTC return to clinic
RU resin uptake
RUL right upper lobe
RUQ right upper quadrant
RV residual volume
RVH right ventricular hyperthrophy
Rx treatment