Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (739 page)

   Limitations

   Drugs and proteins that may increase serum β
₂
-microglobulin levels include cefuroxime, cyclosporin A, gentamicin, interferon-α, pentoxifylline, tumor necrosis factor, lithium, and radiographic contrast media.

   Drugs that may decrease serum β
₂
-microglobulin levels include zidovudine.

   Drugs that may increase urine β
₂
-microglobulin levels include azathioprine, cisplatin, cyclosporin A, furosemide, gentamicin, mannitol, nifedipine, sisomicin, and tobramycin.

   Drugs that may decrease urine β
₂
-microglobulin levels include cilostazol.

BICARBONATE (HCO
₃
-), BLOOD

   Definition

   Bicarbonate is an indicator of the buffering capacity of the blood. Low bicarbonate indicates that a larger pH change will occur for a given amount of acid or base produced.

   Bicarbonate in the blood is calculated from the pH and PCO
₂
using the Henderson-Hasselbalch equation.

   
Normal range:

   Arterial: 21–28 mEq/L

   Venous: 22–29 mEq/L

   Use

   Significant indicator of electrolyte dispersion and anion deficit.