Medical Terminology - When Size Matters - What Your Doctor Is Saying - Harvard Commentaries

Diseases can often change the size of various body parts. So when doctors need to describe the heart or lungs, or abnormal findings such as tumors by their size, you might think the words "big" and "small" would do just fine. What could be more efficient?

Yet medical language replaces these simple terms with ones that are less readily understood. Perhaps saying "cardiomegaly" is more precise or efficient than saying "the heart is big," but it's also much harder for the non-medical person to understand.

Knowing a few suffixes, prefixes and specific terms can go a long way toward helping you understand what your doctor is saying. Here are a few examples.

Disease or the body's adaptations to a disease often causes a vital organ or body part to enlarge. Heart enlargement is a common condition, often a result of high blood pressure, an abnormal heart valve or congestive heart failure.

Almost any organ can enlarge under the right circumstances. In fact, heart failure can not only lead to heart enlargement but it can cause liver enlargement as well. That's because as fluid backs up behind a poorly pumping heart, it can wind up in the liver, making it congested (and enlarged). The extremities can enlarge when a pituitary tumor produces too much growth hormone. In each of these situations, the suffix "-megaly" is used to describe enlargement:

Cardiomegaly – heart enlargement
Hepatomegaly – liver enlargement, which is most commonly due to hepatitis or heart failure
Splenomegaly – spleen enlargement, which often complicates liver disease or a blood disorder
Acromegaly – extremity enlargement; although arm or leg enlargement may develop for a number of reasons (such as a blood clot, infection, or heart failure), the term, "acromegaly" refers to a specific condition in which excessive growth hormone is produced by a tumor of the pituitary gland

Another term is sometimes used to describe enlarged organs. When the tongue is enlarged, for example, it's not called "tongue-omegaly" or even "glossomegaly" (since the root for tongue is "gloss-"). The actual term is macroglossia. "Macro" is a prefix that means "large," similar to the suffix "megaly." Other "macro-" words include:

Macrocytosis – large cells, which can occur when a person has too little vitamin B12 in the body and the red cells become larger than normal
Macrosomia – an enlarged body; this term is often used to describe a fetus that is larger than usual
Macrocephaly – an unusually large head; this may occur in a healthy person, or in a fetus or a growing child as part of a developmental abnormality

The most common prefix to describe something small is "micro." It appears in everyday words such as microscope and microchip. Here are some medical examples of its use:

microcytosis – small cells; iron deficiency can cause red blood cells to become microcytic
micrognathia – small jaw; this may be an inherited or developmental abnormality or a result of arthritis of the jaw if it occurs during childhood (as with juvenile rheumatoid arthritis)
microsomia – an unusually small body, which is used to describe an underdeveloped child
microorganism or microbe – a small (microscopic) infectious agent, such as a virus or bacterium

In addition to descriptions of big and small, doctors commonly use medical terms for "too much" or "too little." Hypertension, for example, is another term for high ( too much ) blood pressure and hyperthyroidism is a condition marked by an excess of thyroid hormone in the body.

By contrast, "hypo" is a prefix indicating there is too little of something. Hypotension means low ("too little") blood pressure and hypothyroidism means there is too little thyroid hormone in the body.

osteopenia – too little bone; this term describes a mildly reduced amount of bone, which may progress to osteoporosis if bone loss continues
neuroglycopenia – too little sugar in the brain; when blood sugar is quite low — usually when a person with diabetes takes too much insulin — the brain is deprived of glucose and can't function normally; neuroglycopenia causes poor mental function or confusion
erythrocytopenia – too few red blood cells, which is common in anemia

When something is completely absent, the prefix "a-" is often used. It means "without" as in:

anencephaly – absent brain development
anosmia – lack of sense of smell
anesthesia – lack of sensation, pain or awareness

Plenty of "regular" words use this prefix to mean "without:" amnesia (lack of memory) and amoral (lack of morals), for example.

In medical terminology, there are many ways to describe size and quantity. In my view, the best words to use are also the easiest to understand. While we doctors fall easily into the habit of speaking our own private language, I believe little is gained by using technical terms to describe big, small, plentiful and scarce. If you don't understand what your doctor is saying, ask him or her to use "regular" words, regardless of whether they are big or small.