CSAD and chronic kidney disease: In contrast, when expression of CSAD protein was assessed by immunoblotting in the livers of the NxC group of CKD rats, this showed a clear decrease to 45% of the value in sham operated control animals (S) (Fig. 1a, b), consistent with the reduction in the taurine flux into urine in the NxC group (36% of the S value in Table 3) and the accompanying reduction in the urinary taurine/ SO42− excretion ratio (36% of the S value in Table 3).