In four adolescents (two girls and two boys), who were investigated for galactorrhoea or short stature, we found moderately elevated serum prolactin (PRL) levels, but without a decreased gonadotropin and sex hormone production. Serum PRL levels were not responding to the intravenous injection of thyrotropin releasing hormone. Magnetic resonance imaging of the hypothalamic-pituitary region revealed no abnormality. Initial diagnoses were idiopathic and drug-induced hyperprolactinaemia. The presence of anti-prolactin auto-antibodies was suspected because of low recovery of PRL after precipitation with polyethylene glycol and confirmed by immunoprecipitation with anti-human IgG-agarose.
Conclusion: anti-prolactin auto-antibodies causing high prolactin values in some immunoassays can cause hyperprolactinaemia in adolescents without other signs of hormonal disturbances or auto-immune disease.