The application of protease inhibitor to urine cell collection


Session type:

Bensita.M.V Thottakam1, Alessia Donnini1, Mary McKean2, Linda Gordon2, Durgesh Rana3, Marina Perrera3, Sian Chilcott4, Marie Corcoran4, Alex Wilson5
1Cytosystems Ltd, Aberdeen, UK, 2NHS Grampian, Aberdeen, UK, 3Manchester Royal Infirmary, Manchester, UK, 4Addenbrookes Hospital NHS Trust, Cambridge, UK, 5Robert Gordon University, Aberdeen, UK


Much emphasis has been given to the preservation of fresh urine samples in patients attending urology outpatient clinics. It was believed that addition of a protease inhibitor (Protease Inhibitor Cocktail Tablet, Roche Cat.No.11 836 145 001) could maintain cell integrity in urine specimens. The aim of this study was to examine the net added value of a protease inhibitor to such an urine collection.


50 patients who routinely attended the outpatient Urology Department at Addenbrookes Hospital, Cambridge provided urine samples into a standardised clean container. These samples were then inverted several times to ensure adequate mixing, split into two parts to one of which a “complete” Protease Inhibitor tablet was added. The urines were transferred directly to the laboratory, and processed using a novel cell collection device designed to capture and preserve cells. Slides were prepared using a ThinPrep 2000 processor. The paired slides were then read at two separate centres (Aberdeen Royal Infirmary, Manchester Royal Infirmary) by senior qualified Cytopathologists and assessed as to cell content, morphology and any degree of apoptosis. Total cell counts and quality of cell preparation were assessed using an ordinal scale as: 3 - Very high, 2 – Moderate, 1 – Low, 0 – Insufficient. A Wilcoxon Signed Rank test was used for comparison.


There was no evidence that cellular degradation was in any way prevented by the addition of protease inhibitor to the urine samples.  Statistical analysis did not show a significant difference in cell count between samples treated with or without Protease Inhibitor (p-Value = 0.317)


Preliminary data clearly indicated that the addition of an expensive protease inhibitor tablet does not improve the cellular integrity of preserved urines as opposed to those urines without added PI, all of which are processed within a 4-hour period from the time of void.