Details

Autor(en) / Beteiligte

• Borrego-Utiel, Francisco-Jose
• Merino Garcia, Enoc
• Garnica Alvarez, Maria Luisa
• Moriana Dominguez, Clara

Titel

MO130GLOMERULAR FILTRATION RATE IS THE MAIN PREDICTOR OF URINE OUTPUT IN AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE (ADPKD) PATIENTS TREATED WITH TOLVAPTAN

Ist Teil von

• Nephrology, dialysis, transplantation, 2021-05, Vol.36 (Supplement_1)

Erscheinungsjahr

2021

Quelle

Oxford Journals 2020 Medicine

Beschreibungen/Notizen

• Abstract Background and Aims Tolvaptan was approved to treat autosomal dominant polycystic kidney disease (ADPKD) to slow the rate of kidney growth and renal function decline. Tolvaptan blocks the V2 vasopressin receptor in renal collecting ducts and distal nephron causing intense polyuria. Few authors have analyzed what factors influence the volume of diuresis in patients taking tolvaptan. Method We have analyzed the influence of solute excretion and glomerular filtration rate, besides age and gender as predictors of urine output, using multivariable analysis. In concret, we have searched the importance of osmolar excretion as predictor of volume of diuresis. Results We studied 24 h-urine samples from 18 ADPKD patients on treatment with tolvaptan, who had received the three doses: 45/15, 60/30 and 90/30 mg. Each patient was represented once per dose, for a total of 54 urine samples (Table 1). Tolvaptan increased urine volume, which was roughly doubled, and roughly halved urine solute concentrations expressed by volume and calculated osmolality. By contrast, solute concentrations expressed as ratios with creatinine remained constant as did osmolality corrected with urinary creatinine, indicating that there was no change in solute excretion after tolvaptan. Urine volume was correlated with serum creatinine (Rho= -0.36, p= 0.008), urinary creatinine (Rho = -0.29, p = 0.034) and GFR-MDRD4 (Rho = 0.44, p= 0.001). Urine volume was correlated with calculated daily osmolar excretion in Osm/day (Rho = 0.76, p <0.001). Urine volume was not correlated with calculated urinary osmolality in mOsm/Kg (Rho= -0.04, p= 0.77) or as urinary osmolality/creatinine ratio (Rho= 0.23, p= 0.1). Correlation of urine volume with osmolar excretion was lost when urine volume was removed from the predictor variable. Urine volume was additionally not correlated with urinary urea o sodium concentrations nor their solute/creatinine ratios, and although it was correlated with urinary potassium concentration (Rho = -0.33, p=0.014), it was not correlated with potassium/creatinine ratio. We also performed a linear regression analysis searching predictors of urine volume. Only GFR and the osmolality/creatinine ratio were significant predictors of urine volume (urine volume= 55.35 x GFR + 4.74 x Osmolality/Cr; r2= 0.41, p<0.001) but individual solute assessments or tolvaptan dose did not predict urine volume. Conclusions Therefore, urine volume after initiating tolvaptan in patients with ADPKD is influenced mainly by the degree of renal function. There might also be a contribution of urinary solute load but it can not be studied using total solute excretion due to collinearity. We propose that the urinary solute/creatinine ratio and osmolality/creatinine ratio should be used to search for predictors of urine output in patients on tolvaptan.