The investigation of proteinuria

Determination of human albumin in serum and urine samples by constant-energy synchronous fluorescence method

A sensitive spectrofluorimetric method using constant-energy synchronous fluorescence technique is proposed for the determination of human albumin without separation. In this method, no reagent was used for enhancement of the fluorescence signal of albumin in the solution. Effects of some parameters, such as energy difference between excitation and emission monochromators (ΔE), emission and excitation slit widths and scan rate of wavelength were studied and the optimum conditions were established. For this purpose factorial design and response surface method were employed for optimization of the effective parameters on the fluorescence signal. The results showed that the scan rate of the wavelength has no significant effect on the analytical signal. The calibration curve was linear in the range 0.1-220.0 µg mL(-1) of albumin with a detection limit of 7.0 × 10(-3)  µg mL(-1). The relative standard deviations (RSD) for six replicate measurements of albumin were calculated as 2.2%, 1.7% and 1.3% for 0.5, 10.0 and 100.0 µg mL(-1) albumin, respectively. Furthermore the proposed method has been employed for the determination of albumin in human serum and urine samples.

Analytical interference of quinolone antibiotics and quinine derived drugs on urinary protein determined by reagent strips and the pyrogallol red-molybdate protein assay

OBJECTIVES

To investigate the analytical interference of drugs in urinary protein and to estimate the lowest interfering concentrations.

DESIGN AND METHODS

Drug supplemented urine samples were compared to the control with two reagent strips and the total protein was determined using Pyrogallol Red-Molybdate (PRM).

RESULTS

False-positive interferences occurred with Multistix 10 SG for hydroxychloroquine, levofloxacin and ofloxacin. No interference was observed with Combur 10 Test M. Statistically significant false-positive interferences were observed in the PRM assay with all tested drugs, and lowest interfering concentrations were mostly above estimated therapeutic concentrations. The PRM assay "confirmed" the results of the Multistix dipstick, so a real proteinuria could be presumed from the double analytical interference.

CONCLUSIONS

This is the first report of analytical interference by quinolone and quinine derivatives in the PRM assay. Special attention to patients using these drugs is needed to minimize errors in the interpretation of urinary protein results.