Dictionary

phenylketonuria, maternal See PKU, maternal.

pheresis A procedure in which the blood is filtered and separated, and a portion is retained, with the remainder being returned to the individual. There are various types of pheresis. For example, in leukapheresis, the leukocytes (white blood cells) are removed; in plateletpheresis, the thrombocytes (blood platelets) are removed; and in plasmapheresis, the liquid part…

pheromone An agent secreted by an individual that produces a change in the sexual or social behavior of another individual of the same species; a volatile hormone that acts as a behavior-altering agent.

Philadelphia chromosome Abbreviated Ph, the hallmark of chronic myeloid leukemia (CML), a small chromosome 22 that was shortened in a reciprocal exchange of material with chromosome 9. This translocation occurs in a cell in the bone marrow and causes CML. It is also found in a form of acute lymphoblastic leukemia (ALL). On a molecular…

philtrum The area from below the nose to the upper lip. Normally the philtrum is grooved. In fetal alcohol syndrome, the philtrum is flat.

phimosis A condition in which the foreskin of the penis is too tight to be pulled back to reveal the glans. This usually causes no problems and nothing needs be done. If phimosis causes obstruction of the urinary stream, meaturia (blood in the urine), or pain, this can require surgery to relieve the phimosis. Circumcision…

phlebitis Inflammation of a vein. With phlebitis, there is infiltration of the walls of the vein and, usually, the formation of a clot (thrombus) in the vein (thrombophlebitis). Phlebitis in a leg, for example, causes the leg to swell with fluid (edema). Phlebitis can be superficial and not very serious, or it can be deep…

phlebo- Prefix meaning vein, as in phlebitis (inflammation of the veins) and phlebotomist (a person who draws blood from veins).

phlebotomist A person who draws blood for diagnostic tests or to remove blood for treatment purposes.

phlebotomy The field of obtaining blood from a vein. Phlebotomy is done by puncturing a vein with a needle. Phlebotomy may be done in order to obtain blood for diagnostic tests or to remove blood for treatment purposes (for example, to relieve iron overload in hemochromatosis).

phobia An unreasonable sort of fear that can cause avoidance and panic. Phobias are a relatively common type of anxiety disorder. Phobias can be treated with cognitive behavioral therapy, using exposure and fear-reduction techniques. In many cases, antianxiety or antidepressant medication proves helpful, especially during the early stages of therapy.

phocomelia A birth defect in which the hands and feet are attached to abbreviated arms and legs. The term comes from phoco (meaning “seal”) and melia (meaning “limb”), to indicate that a limb is like a seal’s flipper, as in exposure of the developing fetus to thalidomide. Phocomelia may also, in some cases, be genetic.