Anion


Anion: A negatively charged ion. Pronounced an-I-on.

An anion is as opposed to a cation, which is a positively charged ion.

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  • 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-

    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

    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 […]

  • Anisocytosis

    Anisocytosis: Excessive inequality in the size of the red blood cells. Anisocytosis is apparent on a blood smear examined under a microscope.

  • Anisometropia

    Anisometropia: The condition in which the two eyes have unequal refractive power. One eye may be myopic (nearsighted) and the other hyperopic (farsighted) or one eye may be markedly stronger than the other. Anisometropia is a serious concern in newborns and young children because it can lead to amblyopia (impaired vision in one eye). With […]


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