ANA: Antinuclear antibody, an unusual antibody directed against structures within the nucleus of the cell. ANAs are found in patients whose immune system is predisposed to cause inflammation against their own body tissues. Antibodies that are directed against one’s own tissues are referred to as autoantibodies. The propensity for the immune system to work against its own body is referred to as autoimmunity. ANAs indicate the possible presence of autoimmunity.
An-: Prefix very much employed in medicine and all of the health sciences, indicating “not, without, or -less.” For example, the prefix “an” figures into these words: anemia (without blood), anophthalmia (no eye), anotia (no ear), anoxia (no oxygen). The “an-” usually becomes “a-” before a consonant as, for example, in alexia (not read), aphagia […]
Anion: A negatively charged ion. Pronounced an-I-on. An anion is as opposed to a cation, which is a positively charged ion.
- Anion gap
Anion gap: A measurement of the interval between the sum of “routinely measured” cations minus the sum of the “routinely measured” anions in the blood. The anion gap = (Na+ + K+) – (Cl- + HCO3-) where Na- is sodium, K+ is potassium, Cl- is chloride, and HCO3- is bicarbonate. The anion gap can be […]
Aniso-: Unequal, unlike, or dissimilar. As in anisocoria, anisocytosis, and anisometropia. From the Greek anisos meaning unequal, from an-, not, + isos, equal. The opposite of aniso- is iso-.
Anisocoria: A condition in which the left and right pupils of the eyes are not of equal size. The size of the pupil determines how much light is let into the eye. With anisocoria, the larger pupil lets more light enter the eye. There are many causes of anisocoria, including eye injury or infection and […]