[Diagnostic difficulties in recognizing of pheochromocytoma].

Pheochromocytoma (PH) is a tumour of chromaffin cells of the sympathetic nervous system and its clinical symptoms are associated with excessive production and release of catecholamines. The main criterion for clinical diagnosis of PH is finding increased concentrations of catecholamines or their metabolites in serum and/or urine. The largest diagnostic and therapeutic problems are patients with slightly elevated levels of methoxycatecholamines in serum and/ or urine. Aim of this study was to determine the cut-off point for elevated methoxycatecholamine in the collection of daily urine, which would give the basis for determining the reasonable recommendations of the biochemical criteria for diagnosis of PH. Retrospectively we analysed the results of 45 patients sent to laparoscopic adrenalectomy to the Department of General Surgery II with the preoperative diagnosis of pheochromocytoma. The diagnosis of pheochromocytoma was based on the finding of elevated 24-hour urine methoxycatecholamines. Based on the results of the histopathological examination patients were divided into two groups. Group 1 included 27 patients (14 women and 13 men) with histopathologically confirmed pheochromocytoma of adrenal gland. Group 2 consisted of 18 patients (11 women and 7 men), in which histopathological examination did not confirm the presence of pheochromocytoma. Mean age of patients in group 1: 46.8 +/- 14.4 years, in group 2: 55.7 +/- 13.7 years. Hypertension was diagnosed in 77.8% of those with group 1 and 94.4% from group 2. Based on the analyzed results of the CT, we found that the average tumor size in group 1 (4.2 +/- 1.9 cm) was statistically higher than in group 2 (2.9 +/- 1.1 cm). The average concentration of normetanephrine (NMN) in 24-hour urine in group 1 was statistically significantly higher than in group 2 (2,686 +/- 870.4 vs. 2375.1 +/- 754 mg/24h), as well as the average concentration of metanephrine (MN) (2533.4 +/- 3269.3 +/- 491.6 vs. 371.5 mg/24 hrs), and the sum of both methoxycatecholamines (NMN + MN) (5219.3 +/- 5190.6 vs. 1241.8 +/- 1202.2). The highest sensitivity in diagnosing pheochromocytoma with the rate of 81.5% was obtained for the sum of normetanephrine and metanephrine in 24-hour urine, while the sensivity for levels of each methoxycatecholamine separately was similar (63%). The highest specificity in the exclusion of PH was shown for 24-hour urine metanephrine (94.4%). The highest positive predictive value was found for the level of metanephrine in 24-hour urine (94.4%). The diagnostic cutoff concentrations of NMN, MN and NMN + MN for the diagnosis of pheochromocytoma were set. For the 24-hour urine NMN- cut-off > 1500 ug/24 h, for MN > 700 ug/24h and for NMN + MN > 1350 ug/24h. Shown above cut-off levels of methoxycatecholamines urine concentration will allow to pose a more accurate preoperative diagnosis of PH.