Parathyroid hormone-, 25-OH-vitamin D-, and digoxin levels in patients treated by chronic hemofiltration.

Immunoreactive parathyroid hormone (iPTH) was measured in the serum and filtrate before, during and after hemofiltration. iPTH regularly declines during hemofiltration; one patient, investigated for a longer period, showed a normalization of iPTH serum level with this treatment. The iPTH values found in the hemofiltrate were remarkably high, a finding that could be explained by non-specific effects, by the occurrence of hormone fragments or by an increased secretion rate. At any rate, the results suggest a filtration of parathyroid hormone and/or hormone fragments. On the other hand, it was impossible to detect any 25-OH-vitamin D in the hemofiltrate. Finally, digoxin could be found in the filtrate, but only in very low concentrations.