Lactate is metabolized mostly by the liver. Therefore, impaired liver function (as evidenced by an ALT of 92 mmol/L) will most inhibit the clearance of lactate from the blood. The kidneys clear lactate to a lesser extent; impaired kidney function will affect the clearance, but less so than liver function. A PaO2 of 68 mm Hg is within normal range; this value will not cause increased production lactate that must be cleared.