This article is from the Interpretation Of Lab Test Profiles, by Ed Uthman email@example.com with numerous contributions by others.
Increase of LD activity in serum may occur in any injury that
causes loss of cell cytoplasm. More specific information can be
obtained by LD isoenzyme studies. Also, elevation of serum LD is
observed due to in vivo effects of anesthetic agents,
clofibrate, dicumarol, ethanol, fluorides, imipramine,
methotrexate, mithramycin, narcotic analgesics, nitrofurantoin,
propoxyphene, quinidine, and sulfonamides.
Decrease of serum LD is probably not clinically significant.
There are two main analytical methods for measuring LD:
pyruvate->lactate and lactate->pyruvate. Assay conditions
(particularly temperature) vary among labs. The reference range
for the assaying laboratory must be carefully studied when
interpreting any individual result.
Many European labs assay alpha-hydroxybutyrate dehydrogenase
(HBD or HBDH), which roughly equates to LD isoenzymes 1 and 2
(the fractions found in heart, red blood cells, and kidney).