R/O

Medical abbreviation for rule out.

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r-tPA
Tissue plasminogen activator.
R (symbol)
A doctor’s note of a burn on the “R digit 5” places the burn on the right little finger or toe. Roentgen, an international unit of X-radiation or gamma-radiation. In chemistry, a radical. On a prescription, R (or Rx), recipe, which is Latin for “to take”.
RDS (respiratory distress syndrome)
Formerly known as hyaline membrane disease, a syndrome of respiratory difficulty in newborn infants caused by a deficiency of a molecule called surfactant. RDS almost always occurs in newborns born before 37 weeks of gestation. The more premature the baby is, the greater is the chance of developing RDS. RDS is more likely to occur […]

Reabsorption
Being absorbed again. For example, the kidney selectively reabsorbs substances it has already secreted into the renal tubules, such as glucose, protein, and sodium. These reabsorbed substances are returned to the blood.
Reaction kinetics
The rate of change in a biochemical (or other) reaction.