Protein oxidation, glycation, and carbamylation in patients with adrenal masses.

Adrenal masses are the most common of all tumors in the adult population, and their size is associated with malignancy. The knowledge about the pathogenesis of adrenal tumors is limited. Objectives: Evaluation of the association between protein glycooxidation and carbamylation, as well as thiol-disulfide homeostasis and adrenal tumor size. The study group included 71 patients (39 women and 32 men) with adrenal masses, divided into two groups: 34 patients with adrenal masses <4 cm in diameter and 37 patients with adrenal masses >4 cm in diameter. Colorimetric and spectrophotometric methods were used in this study. The protein oxidative damage (increase in ischemia-modified albumin) and glycooxidation rate (increase in kynurenine, dityrosine, Amadori products, advanced glycation end products, and carbamyl-lysine [CBL]) were significantly higher in patients with adrenal masses than in comparison with the control group. Additionally, thiol-disulfide homeostasis (decrease in total thiols and native thiols and increase in disulfide) was disturbed in these patients. The plasma content of CBL seemed to express possible diagnostic utility. This parameter, with 75.68% sensitivity and 74% specificity, differentiates patients with adrenal tumors (both AM < 4 cm and AM > 4 cm) from the controls. Moreover, plasma content of CBL has a diagnostic value in distinguishing AM < 4 cm from those AM > 4 cm. In conclusion, protein glycoxidation and thiol-disulfide homeostasis are impaired in patients with adrenal tumors. Although oxidative stress is involved in the progression of carcinogenesis, oxidation and glycoxidation of plasma proteins, as well as thiol-disulfide homeostasis, were not dependent on tumor size. Only the evaluation of CBL plasma content seems helpful in predicting the malignant risk of adrenal masses. More research is needed to confirm our results.