physician assistant A midlevel practitioner who is able to practice medicine under the auspices of a licensed physician (MD or DO). Abbreviated PA. Although the physician need not be present during the time the PA performs his or her duties, there must be a method of contact between the supervising physician and the PA at…
physician-assisted suicide The provision of equipment, medication, or information to a patient by a physician for the purpose of assisting the patient in ending his or her own life.
Physicians’ Desk Reference A book that provides a guide to all the prescription drugs available in the US. Abbreviated PDR. PDR is a key reference to the US pharmacopeia and is published annually.
physiologic Something that is normal, that is due neither to anything pathologic nor significant in terms of causing illness. For example, physiologic jaundice is jaundice that is within normal limits.
physiologic jaundice Jaundice that is within normal limits. A newborn may have physiologic jaundice due to the release of the pigment bilirubin (from red blood cells) that the immature liver cannot process for excretion in the urine. Physiologic jaundice causes no illness and clears up in a few days.
physiology The study of how living organisms function, including such processes as nutrition, movement, and reproduction.
phytanic acid storage disease See Refsum disease.
phenomenon, phantom limb See phantom limb syndrome.
phenotype An appearance or characteristic of an individual, which results from the interaction of the person’s genetic makeup and his or her environment. By contrast, the genotype is merely the genetic constitution (genome) of an individual.
phenylalanine An essential amino acid that is required in the human diet. Abbreviated phe. Most of the phe that is ingested is transformed (hydroxylated) to form tyrosine, which is used in protein synthesis. Too little phe does not permit normal physical and intellectual growth. Too much phe (as in PKU) is highly toxic to the…
phenylalanine hydroxylase deficiency The inherited inability to normally process the amino acid phenylalanine, due to partial or complete deficiency of the enzyme phenylalanine hydroxylase. This deficiency is caused by mutation in the PAH gene on chromosome 12. Phenylalanine hydroxylase deficiency causes a spectrum of disorders, including classic phenylketonuria (PKU), variant PKU, and nonPKU elevation of…
phenylketonuria See PKU.