[Diurnal changes in the levels of immunoreactive parathyroid hormone and calcitonin in patients with chronic renal insufficiency].

The circadian rhythms of the serum immunoreactive parathyroid hormone (iPTH) and calcitonin concentration were examined in 6 patients with chronic renal failure (CRF) not treated by haemodialysis. In 3 patients on haemodialysis the influence of haemodialysis with cuprophan and polyacrylonitrile membranes (in a.m. and p.m. periods of day) on serum concentration of these was investigated. The results demonstrate that in patients with CRF in predialysis period the circadian rhythm of serum iPTH concentration is at least partially preserved. However, the effect of dialysis on serum C-terminal iPTH concentration showed a sharp progressive fall of the concentration during haemodialysis on polyacrylonitrile membranes. The study of the circadian rhythm of serum calcitonin concentration in CRF patients with the six hours intervals between blood sampling could not reveal changes which favour the opinion of the existence of circadian rhythmicity. In patients on haemodialysis during haemodialysis with cuprophan membranes a rise of serum calcitonin concentration was observed.