Introduction:
Pyruvate kinase in an enzyme that catalyzes the production of pyruvate and ATP as the final step of the glycolysis. Potential role of Pyruvate kinase in tumorigenesis was previously suggested, due to its altered activity in several tumors.

Material and methods:
This study looks at M2 isozyme of pyruvate kinase activity (M2-PK) measured in peripheral and uterine blood plasma in various stages of endometrial cancer (EC) as well as in precancerous state of atypical endometrial hyperplasia (AEH). Measurements were performed using spectrophotometric method in citrate plasma samples from peripheral and uterine blood. Study group included 84 patients with endometrial cancer, 28 patients with atypical endometrial hyperplasia and 23 non-cancerous controls.

Results:
Pyruvate kinase activity in EC group was 3-fold higher than in control group both in peripheral and uterine blood samples. Pyruvate kinase activity was also 3-fold higher in uterine blood when compared to peripheral blood samples. We also found statistically significant correlation between FIGO staging and detected activity with the M2-PK activity being 2-fold higher for FIGO1 than for FIGO3. We also describe a paradox in which the M2-PK activity in patients with atypical endometrial hyperplasia is lower than M2-PK activity in control group in peripheral blood samples, but higher in uterine blood samples.

Conclusions:
The measurement of citrate plasma pyruvate kinase metabolic activity varies greatly between samples collected from different sites and samples collected from patients with varied tumor staging. Further studies are needed in order to elucidate molecular pathways that are responsible for observed differences.