| A-a O2 | alveolo-arterial oxygen tension |
|---|---|
| AaPCO2, (A-a)PCO2 | alveolo-arterial carbon dioxide tension difference |
| AaPO2, (A-a) PO2 | alveolo-arterial oxygen tension difference |
| CTH | ceramide trihexoside; chronic tension headache; cystathionase |
| ht | heart; heart tones; height; high tension |