Antipituitary antibodies in dutch patients with idiopathic hypopituitarism

Despite extensive research, in the majority of patients with isolated growth hormone deficiency (IGHD) and multiple pituitary hormone deficiency (MPHD), the cause of their clinical picture remains unknown. Recent articles suggest that some cases of idiopathic growth hormone deficiency might be explained by a silent form of autoimmune hypophysitis based on the presence of antipituitary antibodies (APA) at high titers (>1:8).

We collected clinical data and serum from 71 patients participating in the Dutch HYPOPIT study. APA screening in 40 IGHD patients and 31 MPHD patients was performed by an indirect immunofluorescence method. APA, when present, were related to clinical and morphological pituitary findings.

APA were present at high titers in 7 of 31 MPHD patients (23%) and 1 of 40 IGHD patients (2.5%). Among APA-positive MPHD patients, apart from growth hormone deficiency, all patients of pubertal age had gonadotroph defi- ciency, all had thyroid hormone deficiency and 50% had ACTH deficiency.

The high frequency of APA in our idiopathic MPHD population indicates that, in 23% of the patients diagnosed with idiopathic MPHD, the hormone deficiencies might actually be caused by a silent form of autoimmune hypophysitis. Screening for APA should therefore be considered in all patients with 'idiopathic' MPHD.