Peptide hormones: renal handling and dialysis therapy.

For uraemic diabetics the loss of insulin by dialysis with highly permeable membranes has clinical relevance. We investigated renal handling (in isolated perfused rat kidneys) of insulin and c-peptide and their dialytic clearances and sieving coefficients using cuprophan and polyacrylonitrile membranes. Rat kidney catabolic clearances were five times (insulin) and 12 times (c-peptide) greater than urinary clearances and twice inulin clearance. Cuprophan membrane was found to be virtually impermeable for both hormones. Polyacrylonitrile sieving coefficients were 0.3 (insulin) and 0.4 (c-peptide). Both hormones are filtered as well as tubularly and peritubularly catabolised in the kidney. Insulin removal during dialysis and haemofiltration with polyacrylonitrile membranes has to be considered in treating uraemic diabetics.