Homocysteine: new tumor marker in pleural fluid.

There are no published studies examining the utility of total homocysteine (HCY) in pleural fluid. The aim was to measure the accuracy of pleural fluid HCY concentration for diagnosis of malignant pleural effusion (MPE). We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. Pleural fluid HCY concentration was measured by immunonephelometry using N Latex HCY reagent with monoclonal antibody in automated analyzers BNII (Siemens Diagnostics®). Patients were classified into two groups according to the etiology of pleural effusion: benign pleural effusions (BPE) and MPE. Pleural effusion was categorized as MPE if malignant cells were demonstrated in pleural fluid or pleural biopsy. The accuracy of pleural fluid HCY concentration for diagnosis of MPE was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC). We studied 89 patients with ages between 1 and 96 years old (median = 66). Forty-eight patients were BPE and 41 were MPE. Pleural fluid HCY concentration was significantly higher in patients with MPE (median = 13.70 µmol/L) than in those with BPE (median = 8.05 µmol/L). The AUC value was 0.833 (95 % confidence interval (CI) 0.739-0.903). The optimal cutoff value was 13.1 µmol/L exhibiting 56.1 % (95 % CI 39.8-71.5) sensitivity and 85.4 % (95 % CI 72.2-93.9) specificity. Pleural fluid HCY concentration showed high diagnostic accuracy to predict whether a pleural effusion is benign or malignant. Pleural fluid HCY concentration may be measured easily and quickly in automated analyzers and could be a tumor marker commonly used for diagnosis of MPE.

Serum lactate dehydrogenase in combination with free-to-total serum prostate specific antigen ratio for diagnosis of prostate cancer.

BACKGROUND: Evaluate the utility of serum lactate dehydrogenase (LDH) in combination with free-to-total serum prostate specific antigen ratio (%fPSA), for diagnosis of prostate cancer (PC) with serum total prostate specific antigen (PSA) levels in the intermediate range of 4 to 10 ng/mL. METHODS: The following variables were analysed: PSA, %fPSA, and LDH. Two categories of patients were included in the analysis: NOT PC and PC. RESULTS: We studied 134 patients, 112 had NOT PC and 22 had PC. We defined the following multivariable score (S): S = A + B, where A and B are coefficients of LDH and %fPSA, respectively. AUC values were 0.719 (p = 0.0036), 0.749 (p = 0.0082), and 0.816 (p = 0.0001) for %fPSA, LDH, and S, respectively. Using the proposed S increases by 18% specificity compared to only using the %fPSA parameter. CONCLUSIONS: LDH in combination with %fPSA improves diagnostic performance for detection of PC compared to using only %fPSA.