['The peritoneal equilibration test (PET) was developed some 25 yr ago and has been used to help prescribe peritoneal dialysis. However, PET is affected by several factors, including diabetes and inflammation. It was speculated that extracellular fluid overload would increase PET ultrafiltration volumes, and therefore the usefulness of the PET in routine clinical practice was audited.', 'Data from 211 consecutive patients attending a university teaching hospital for a standard PET who had multifrequency bioimpedance performance were analyzed to determine which factors affected net PET ultrafiltration volumes.', 'Net PET ultrafiltration volume was independent of gender, age, diabetes, residual renal function, peritoneal dialysis prescriptions (modes and dialysates), extracellular fluid volume, or C-reactive protein (CRP). There was an inverse regression with serum albumin and sodium on multiple logistical regression analysis (F = 13.4, P < 0.001 and F = 10.1, P = 0.001, respectively) and a positive regression with 24-h net peritoneal ultrafiltration volumes (F = 15.5, P < 0.001). As expected, there was a strong correlation with net sodium losses (r = 0.99, P < 0001).'] Does hydration status influence peritoneal equilibration test ultrafiltration volumes?