Absence of diurnal plasma prolactin rhythm in diabetic and non-diabetic uraemic patients

Abstract

Abstract. The 24 h profile of plasma Prl was studied in 6 non-diabetic uraemic and 5 type I diabetic uraemic patients, the latter brought into a near-normal metabolic and carbohydrate control using an artificial pancreas. Nyctohemeral variation were absent in all 11 subjects (day plasma Prl vs night-levels: 10.1 ± 1.6 ng/ml vs 9.5 ± 1.5 ng/ml, P = 0.09), even in those patients who had a basal Prl within normal limits. Sleep-induced Prl secretion did not re-appear in 5 patients re-studied after several weeks on chronic dialysis treatment (day vs night-levels: 8.9 ± 1.5 ng/ml vs 9.9 ± 1.5 ng/ml, P > 0.10). The absence of night surge was in contradistinction to the Prl profiles observed in 6 healthy subjects (day vs night levels: 6.4 ± 0.9 ng/ml vs 11.3 ± 1.3 ng/ml, P < 0.002) and in 2 type I diabetics with normal kidney function who, as expected, all exhibited a normal circadian Prl rhythm. Brief, episodic Prl secretion during daytime was, however, observed in all the uraemics. The study provides further evidence for a profound dysfunction of the central nervous system in uraemia. The exact mechanism remains unknown.