David Walker of Anderson Moores Vets on 21st October 2014 said:
Your vet will take blood samples to test for Alabama Rot: Azotaemia (abnormally high levels of nitrogen-containing compounds such as urea and creatinine), thrombocytopaenia (decrease of platelets aka thrombocytes), mild anaemia (decrease in red blood cells or amount of hemoglobin) and hyperbilirubinaemia (jaundice with high levels of bilirubin).
Your vet will also take urine samples to test for Alabama Rot: dilute urine and glucosuria (excretion of glucose into the urine) and casts (cylindrical structures produced by the kidney).