Hypothalamic-pituitary-adrenal axis function in patients with active rheumatoid arthritis: a controlled study using insulin hypoglycemia stress test and prolactin stimulation.
OBJECTIVE
To study the response of cortisol and of prolactin (PRL) to specific stimuli in rheumatoid arthritis (RA).


METHODS
We measured the response of cortisol to insulin induced hypoglycemia and of PRL to thyrotropin releasing hormone (TRH) in 10 patients with active RA and in 10 paired control subjects. All were women with regular menstrual cycles. They had never received corticosteroids before the study. The PRL concentration was assessed by chemiluminescence immune assay and the cortisol concentration by radioimmunoassay.


RESULTS
The basal serum levels of cortisol (14.47+/-2.5 microg/dl) and PRL (10.1+/-1.3 ng/ml) in the RA 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 peak value of cortisol after hypoglycemia was comparable in both groups (25.5+/-2.4 microg/dl in RA vs. 26.0+/-1.5 ng/ml in controls). The integrated cortisol response to hypoglycemia expressed as area under the response curve (AUC) did not differ significantly in either group (1927+/-196 in RA vs. 1828+/-84 in controls). The interval-specific "delta" cortisol response was significantly higher for the 30 to 45 min interval in controls compared to patients with RA (9.8+/-0.9 microg/dl vs. 6.1+/-1.1 microg/dl; p = 0.02). The peak of PRL after TRH did not differ significantly in both groups (56.4+/-6.4 ng/ml in RA vs. 66.3+/-7.7 ng/ml in controls) and the AUC of PRL secretion after TRH was comparable in both groups (3245+/-321 vs. 4128+/-541).


CONCLUSIONS
Our findings suggest that active RA is associated with subtle dysfunction of the hypothalamic-pituitary-adrenal glucocorticoid function and normal PRL secretion.
Gutiérrez
M A
MA
Department of Clinical Immunology and Rheumatology, Pontificia Universidad Católica de Chile, Santiago.
García
M E
ME
Rodriguez
J A
JA
Mardonez
G
G
Jacobelli
S
S
Rivero
S
S
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D001172:Arthritis, Rheumatoid / Q000097:blood*; D001786:Blood Glucose / Q000187:drug effects; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007003:Hypoglycemia / Q000097:blood* / Q000139:chemically induced; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D008163:Luminescent Measurements; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000097:blood*; D011863:Radioimmunoassay; D013312:Stress, Physiological / Q000139:chemically induced; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D013997:Time Factors