Predictive role of the immunostaining pattern of immunofluorescence and the titers of antipituitary antibodies at presentation for the occurrence of autoimmune hypopituitarism in patients with autoimmune polyendocrine syndromes over a five-year follow-up.
BACKGROUND
Antipituitary antibodies (APA) are frequently present in patients with autoimmune polyendocrine syndrome (APS).


METHODS
The aim was to evaluate the predictive value of APA for the occurrence of hypopituitarism. A total of 149 APA-positive and 50 APA-negative patients with APS and normal pituitary function were longitudinally studied for 5 yr.


METHODS
APA, by indirect immunofluorescence, and anterior pituitary function were assessed yearly in all patients. The risk for developing autoimmune pituitary dysfunction was calculated using survival and multivariate analysis.


RESULTS
Hypopituitarism occurred in 28 of 149 (18.8%) APA-positive patients but in none of the 50 APA-negative patients. The immunostaining pattern in APA-positive patients involved either isolated pituitary cells [type 1 pattern; n=99 (66.4%)] or all pituitary cells [type 2 pattern; n=50 (33.6%)]. All patients developing pituitary dysfunction throughout the study span had a type 1 pattern. Kaplan-Meier curves for cumulative survival showed a significantly higher rate for developing hypopituitarism in relation to positive APA tests (P<0.005), pattern of immunostaining (P<0.0001), and APA titers (P<0.000001). Cox regression analysis in APA-positive patients with a type 1 pattern demonstrated a significantly (P<0.0001) higher risk for the onset of hypopituitarism in relation to increasing titers of APA.


CONCLUSIONS
APA measurement by immunofluorescence may help to predict the occurrence of hypopituitarism but only when considering the immunostaining pattern and their titers. Combined evaluation of these parameters allows identifying patients at higher risk for pituitary autoimmune dysfunction, thus requiring a strict pituitary surveillance to disclose a preclinical phase of hypopituitarism and possibly interrupt therapeutically the progression to clinically overt disease.
Bellastella
Giuseppe
G
Department of Clinical and Experimental Medicine and Surgery, F. Magrassi, A. Lanzara, Second University of Naples, via Pansini N. 5, 80131 Naples, Italy.
Rotondi
Mario
M
Pane
Elena
E
Dello Iacovo
Assunta
A
Pirali
Barbara
B
Dalla Mora
Liliana
L
Falorni
Alberto
A
Sinisi
Antonio Agostino
AA
Bizzarro
Antonio
A
Colao
Annamaria
A
Chiovato
Luca
L
De Bellis
Annamaria
A
D000328:Adult; D001323:Autoantibodies / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007018:Hypopituitarism / Q000150:complications / Q000175:diagnosis* / Q000276:immunology*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000276:immunology; D016884:Polyendocrinopathies, Autoimmune / Q000150:complications / Q000276:immunology*; D011237:Predictive Value of Tests; D012044:Regression Analysis; D018709:Statistics, Nonparametric
D001323:Autoantibodies