Webster's New World Medical Dictionary

red cell distribution width
See 
CBC.
red-green colorblindness
A form of color-
blindness in which red and green are perceived as
being identical. Red-green colorblindness is the
most common type of colorblindness. It is inherited
in an X-linked recessive manner and affects 6-8 per-
cent of males in the US. Also known as deutan col-
orblindness, deuteranopia, and Daltonism. See also
colorblindness.
reduction division
The first cell division in meio-
sis, the process by which germ cells are formed. In
reduction division, the chromosome number is
reduced from diploid (46 chromosomes) to haploid
(23 chromosomes). Also known as first meiotic divi-
sion and first meiosis.
Reed-Sternberg cell
A type of cell that is seen
microscopically in the affected tissues of patients
with Hodgkin’s disease and is a hallmark of
Hodgkin’s disease. See also 
Hodgkin’s disease.
referral
The recommendation of a medical or
paramedical professional. If one gets a referral to
ophthalmology, for example, the person is being
sent to the eye doctor. In health maintenance organ-
izations (HMOs) and other managed-care schemes,
a referral is usually necessary in order to see any
practitioner or specialist other than the primary
care physician (PCP) and have the service covered.
The referral is obtained from the PCP, who may
require a telephone or office consultation first. The
term referral can pertain both to the act of sending
a patient to another physician or therapist and to the
actual paper authorizing the visit.
referred pain
Pain felt at a site other than where
the cause is situated. An example is the pain from
the pancreas, which is felt in the back. Pain in inter-
nal organs is often referred to sites distant from
them.