Hypothalamic-pituitary-adrenal axis function and prolactin secretion in systemic lupus erythematosus

The objective was to study the response of cortisol and of prolactin (PRL) to specific stimuli in systemic lupus erythematosus (SLE). We measured the response of cortisol to insulin-induced hypoglycemia and of PRL to thyrotropin releasing hormone (TRH) in seven patients with active untreated SLE and in ten paired control subjects. All were women with regular menstrual cycles. With the exception of two patients, they had never received corticosteroids before the study. The basal serum levels of cortisol (12.5+/-2.4 microg/dl) and PRL (10.7+/-1.0 ng/ml) in the SLE group were not significantly different from those of the control group (12.3+/-1.1 microg/dl and 13.7+/-2.4 ng/ml, respectively). The cortisol response after hypoglycemia was significantly lower in SLE patients compared to the control group at 45 min (P=0.01), at 60 min (P = 0.009), and at 90 min (P = 0.001). The integrated cortisol response to hypoglycemia expressed as area under the response curve (AUC) did not differ significantly in either group (1447+/-187 vs 1828+/-84, P = 0.06). Although the peak of PRL after TRH did not differ significantly in both groups (68.0+/-7.4 ng/ml in SLE vs 66.3+/-77 ng/ml in controls) and the AUC of PRL response after TRH was comparable in both groups (4672+/-537 vs 4128+/-541, P = 0.32), the interval-specific 'delta' response was significantly higher in SLE than the control group at 0-60 min (P=0.02) and 0-90 min (P = 0.01) after TRH injection. These findings suggest that active SLE is associated with some degree of dysfunction of the hypothalamic-pituitary-glucocorticoid axis and PRL secretion.