Comparison Between Twenty-Four-Hour Collection and Single Spot Urines for the Detection of Biogenic Amines by High-Performance Liquid Chromatography Tandem Mass Spectrometry.

BACKGROUND: Pheochromocytomas and paragangliomas (PPGL) are neuroendocrine tumors that originate from adrenal medulla or extra-adrenal chromaffin cells, respectively. They produce an excess of catecholamines and their metabolites. Abnormal levels of these biomolecules have been also found in pediatric patients with neuroblastoma (NB). Due to the diurnal fluctuation, the laboratory practice recommends the determination of biogenic amines in acidified 24-h urine samples. However, the collection and acidification of specimens cannot be performed easily, especially for children. Spot urines represent an attractive alternative for the detection of catecholamines and corresponding metabolites.

METHODS: In our study, we enrolled 50 patients with symptoms related to PPGL and we determined the concentration values for both spot and 24-h urine samples using high-performance liquid chromatography tandem mass spectrometry (HPLC/MS-MS). Since day variations of the urinary concentration are due to fluctuations in renal excretion rather than in production, we normalized the concentration of biogenic amines in spot urine and in 24-h urine collection to urinary creatinine concentration. A correlation study between the normalized levels of biogenic amines was performed using a linear regression analysis model and Pearson's correlation coefficients.

RESULTS: We obtained a good correlation of values which suggests an interchangeability of the 24-h and random urine samples. Only for epinephrine a weak correlation was determined.

CONCLUSIONS: Our findings suggest that the sample collection as single spot urine may replace 24-h collection for the detection of urinary biogenic amines by HPLC/MS-MS.