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.

Interchangeability between 24-hour collection and single spot urines for vanillylmandelic and homovanillic acid levels in the diagnosis of neuroblastoma.

The determination of the two urinary catecholamine metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA) is of crucial importance for the diagnosis and follow-up of neuroblastoma (NB). The standard practice for their measurement requires the use of 24-hour collections that are time consuming and difficult to obtain. In this article, we directly demonstrate that 24-hour collections and single spot urines are interchangeable for the determination of HVA and VMA expressed as ratio on creatinine concentration. This study can be useful for a faster management of NB at onset.

Estimation of Daily Proteinuria in Patients with Amyloidosis by Using the Protein-To-Creatinine ratio in Random Urine Samples.

Measurement of daily proteinuria in patients with amyloidosis is recommended at the time of diagnosis for assessing renal involvement, and for monitoring disease activity. Renal involvement is usually defined by proteinuria >500 mg/day. We evaluated the accuracy of the random urine protein-to-creatinine ratio (Pr/Cr) in predicting 24 hour proteinuria in patient with amyloidosis. We compared results of random urine Pr/Cr ratio and concomitant 24-hour urine collections in 44 patients with amyloidosis. We found a strong correlation (Spearman's ρ=0.874) between the Pr/Cr ratio and the 24 hour urine protein excretion. For predicting renal involvement, the optimal cut-off point of the Pr/Cr ratio was 715 mg/g. The sensitivity and specificity for this point were 91.8% and 95.5%, respectively, and the area under the curve value was 97.4%. We conclude that the random urine Pr/Cr ratio could be useful in the screening of renal involvement in patients with amyloidosis. If validated in a prospective study, the random urine Pr/Cr ratio could replace the 24 hour urine collection for the assessment of daily proteinuria and presence of nephrotic syndrome in patients with amyloidosis.

Validation of the Spot Urine in Evaluating 24-Hour Sodium Excretion in Chinese Hypertension Patients.

BACKGROUND: The spot urine method as an alternative approach in estimating daily urine sodium excretion has been proposed for many years. Kawasaki has created an equation to predict daily urinary sodium excretion using second morning urine (SMU) samples which was obtained before breakfast after initial voiding upon arising. Tanaka has developed another equation by examining spot urine samples submitted at random times during the day. A newly published study proposed that the "PM sample," collected in the late afternoon or early evening before dinner, showed a stronger relationship with actual sodium excretion. We aimed to verify the effectiveness of these methods in evaluating 24-hour urinary sodium in Chinese hypertensive patients. METHODS: A total of 334 hypertensive participants were eligible to participate in this study. A total of 222 patients provided qualified SMU samples, Post Meridiem (PM) samples, and complete 24-hour urine collections. RESULTS: Biases using the Kawasaki formula were 2.1 mmol/day for the SMU specimens; for the Tanaka equation, biases of SMU and PM samples were 21.1 and 30.1 mmol/day, respectively. The highest intraclass correlation coefficient (ICC) was 0.64 when the Kawasaki formula was used in PM specimens, with the lowest ICC 0.17 when it is used in SMUs. CONCLUSIONS: Spot urine method is acceptable for estimating 24-hour urinary sodium excretion in hypertensive individuals. Kawasaki's formula is useful for estimating population mean levels of sodium excretion from SMU, although it is not suitable for estimating individual sodium excretion.