Thyroid autoimmunity in hyperprolactinaemic disorders

Abstract

Circulating thyroglobulin antibodies (TgAb) and microsomal antibodies (MsAb) and thyroid function (total and free T4 and T3, TSH basal and after TRH) have been evaluated in 92 hyperprolactinaemic patients (82 females and 10 males; 9 with macroprolactinoma, 22 with microprolactinoma, 4 with acromegaly, 5 with organic lesions of the hypothalamus, 2 with empty sella, 2 with idiopathic hypopituitarism, 2 with primary hypothyroidism, and 46 with idiopathic hyperprolactinaemia). Thyroid function was normal in all cases except 3 with hypothalamic disease and central hypothyroidism, the 2 patients with primary hypothyroidism and 2 with thyrotoxicosis (one due to Graves' disease and one to autonomous thyroid adenoma). High titres of TgAb (\m=ge\1/1250) and/or MsAb (\ m=ge\ 1/1600) were found in the subject with Graves' disease, in one acromegalic, in the 2 primary hypothyroids, and in 12 women with either adenomatous or idiopathic hyperprolactinaemia; low titres of one or both antibodies were found in 9 other euthyroid women and in the one with toxic adenoma. In a control population of 185 subjects studied with the same methods, the prevalence of TgAb and/or MsAb positive (low titres) was 3.3% in females and 2.5% in males. Diffuse thyroid hyperplasia was clinically detectable in 12 euthyroid women and in the one with Graves' disease; 3 others had been previously operated for nodular goitre with histological evidence of Hashimoto's thyroiditis (2 cases) or for a cold nodule; a single thyroid nodule was present in the woman with toxic adenoma and in one euthyroid woman. Most of these subjects also had circulating TgAb and/or MsAb, and a few had increased TSH secretion. No significant differences were found in mean thyroid hormone and TSH levels between euthyroid hyperprolactinaemic subjects and healthy controls, but TRH-stimulated TSH levels were significantly higher in thyroid antibodies positive than negative subjects. These data, in agreement with a few previous reports, suggest that autoimmune thyroid disorders (especially asymptomatic autoimmune thyroiditis) occur in hyperprolactinaemic women with a prevalence far exceeding that observed in many surveys in the general population.The association of autoimmune thyroiditis with prolactinoma has been known for some years (Thorner 1977), but thyroid antibodies were found in that study in only 2 of 38 women, corresponding to the general incidence of circulating thyroid antibodies in the population studied (Tunbridge et al. 1977). Recently, Pelkonen et al. (1982) observed autoimmune thyroiditis in combination with pro¬ lactinoma in 3 of 36 women. The diagnosis of autoimmune thyroiditis was based on the criteria of Gordin et al. (1972), i.e. the presence of circulating microsomal and thyroglobulin antibodies in high titres (> 1/100000 and > 1/25000, respectively). Moreover, the same investigators found exagge¬ rated TSH response to TRH in 4 prolactinoma patients without autoimmune thyroiditis (Pelkonen et al. 1982). It seemed therefore of interest to report our data on thyroi...

Thyroid autoimmunity in patients with hyperprolactinemia: an observational study

“…Another report by Ferrari and cols. reported comparable results: in a group of 82 women with HPRL, 20% had anti-Tg and 12% had anti-microsomal antibodies (22). Most patients were euthyroid in this study.…”

“…Autoimmune diseases are often characterized by altered PRL levels, associated wtih both Th1 of Th2 dominance, which suggest an immunomodulatory role of PRL (21). There are several clinical studies that demonstrate a relationship between HPRL and autoimmune thyroid disease (15,(22)(23)(24). Giusti and cols.…”

Prolactin protects against diabetes induced by multiple low doses of streptozotocin in mice

“…Administration of PRL, under these circumstances, might therefore influence the progression of the inflammatory response. Moreover, several experimental studies and clinical observations have suggested that PRL might be important in the pathogenesis of various autoimmune diseases (Ferrari et al 1983, Berczi 1993, Walker et al 1993, Neidhart 1998, Velkeniers et al 1998, but very few studies have focused on the role of PRL in diabetes mellitus type 1. It is therefore interesting to study whether PRL affects diabetes induced by multiple low doses of streptozotocin (STZ), a well established animal model for the pathogenesis of type 1 diabetes (Like & Rossini 1976, KolbBachofen et al 1988.…”

Anti-Thyroid Antibodies in Patients with Hyperprolactinemia.

“…We conclude from these results that hyperprolactinemia is associated with a high frequency of positive anti-thyroid antibodies. Although Ferrari et al [11] reported a high incidence of positive anti-thyroid antibodies in patients with hyperprolactinemia of various causes, the age and sex effects, the major determinants for the prevalence of positive anti-thyroid antibodies in the general population alluded to above, were not considered in their study. In addition, their patients were associated with miscellaneous endocrine abnormalities including primary hypothyroidism, Graves' disease and acromegaly, thus making the causal relationship between hyperprolactinemia and positive anti-thyroid antibodies obscure.…”