A standardised protocol for the quantification of lactate dehydrogenase activity in saliva.
The literature about salivary lactate dehydrogenase (LDH) activity shows different results, conditioned by the diversity of methods used for sampling, handling and analysis.


OBJECTIVE
The aim of this study was to design a protocol for quantifying salivary lactate dehydrogenase activity.


METHODS
Whole saliva samples were collected from 100 healthy volunteers by chewing a roll of cotton. Lactate dehydrogenase activity determinations were made with the Cobas Mira Plus II autoanalyser using the recommendations proposed by the International Federation of Clinical Chemistry (IFCC) and the French Society of Clinical Biology (SFBC). Samples were stored at room temperature (20-22 degrees C), in the refrigerator (4 degrees C) and freezer (-20 degrees C). The correction capacity of the autoanalyser was evaluated by making serial determinations in samples of saliva diluted in water.


RESULTS
The frozen samples, but not those stored in the refrigerator or at room temperature, showed an important degradation of lactate dehydrogenase activity. When the samples were diluted in water, the lactate dehydrogenase activity varied substantially with the International Federation of Clinical Chemistry method after correction, but not when using the French Society of Clinical Biology method.


CONCLUSIONS
For salivary lactate dehydrogenase activity quantification we suggest that samples be stored at 4 degrees C and analyse with the French Society of Clinical Biology method.
Alonso de la Peña
Víctor
V
School of Medicine and Dentistry, Universidad de Santiago de Compostela, C/Panama 2, 2o dcha, 36203, Vigo, Spain.
Diz Dios
Pedro
P
Lojo Rocamonde
Santiago
S
Tojo Sierra
Rafael
R
Rodríguez-Segade
Santiago
S
D001322:Autoanalysis; D005615:Freezing; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D012463:Saliva / Q000201:enzymology*; D012680:Sensitivity and Specificity
D007770:L-Lactate Dehydrogenase