*'''Creatinine''' and '''potassium''' if the effusion is thought to be a uroabdomen; creatinine levels in a peritoneal sample that are higher than serum concnetrations indicate uroperitoneum. | *'''Creatinine''' and '''potassium''' if the effusion is thought to be a uroabdomen; creatinine levels in a peritoneal sample that are higher than serum concnetrations indicate uroperitoneum. |