Prevalence Of Anti-pituitary Antibodies Research Articles

Look Beyond Gluten in Short Stature with Celiac Disease - A Prospective, Interventional Study.

Short stature (SS) is a common manifestation of celiac disease (CD). After starting gluten free diet (GFD), children usually have catch-up growth (improvement in height SDS of >1 SD). However, few children in remission, even on GFD, lack catch up growth. This study was planned to assess the growth hormone (GH) axis and the prevalence of anti-pituitary antibodies in such patients. It was a single-centre, prospective study. Patients with CD in remission for the last 1 y, having SS and lacking catch-up growth, were included after excluding other common causes of SS. GH dynamics were studied using stimulation tests: Insulin tolerance test, clonidine stimulation test, and glucagon stimulation test. GH deficiency (GHD) was defined as non-stimulable response to 2 GH stimulation tests. Anti-pituitary antibodies were analysed in these patients using rat pituitary extract as antigen. Ten patients (8 girls), with a mean age of 10 ± 2.8 y, in serological remission for CD and lacking catch-up growth, were enrolled. All had a height SDS of < -2. Fifteen age matched children with CD and adequate catch up growth served as controls. GHD was seen in 7 patients (70%), out of whom 2 received GH therapy and had an improvement in the height SDS from -2.7 to -1.4 and from -2.1 to 2.4 (over 1 y), respectively. Anti-pituitary antibodies were seen in significant titres in 55.5% of the cases and 40% of the controls. Children with CD in remission but lacking catch-up growth should be evaluated for GHD.

Prevalence of antipituitary antibodies in acromegaly

Acromegaly is a rare disorder due to an excessive production of growth hormone (GH), typically caused by a GH-secreting pituitary adenoma. Anti-pituitary antibodies (APAs) are often seen in patients with different kinds of pituitary pathologies. Because GH has been proposed as a possible antigen recognized by such antibodies, the prevalence of APAs may be higher in conditions characterized by excessive GH secretion. The primary aim of this study was to compare the prevalence of APAs in patients with acromegaly and in controls with other types of pituitary tumors and healthy subjects. Secondary aim was to characterize the pituitary cells targeted by the APAs. Thirty eight acromegaly patients and 215 controls, including 38 patients with prolactinomas, 64 with non-functioning pituitary adenomas (NFPA), and 113 healthy subjects were enrolled in the study. All subjects were tested for APAs using indirect immunofluorescence. Target cells recognized by APAs were identified by double staining immunofluorescence. APAs were significantly more prevalent in acromegaly cases than in healthy controls (10.5% vs. 1.8%, P < 0.05). This prevalence was similar to that found in patients with prolactinomas (7.9%) and NFPA (12.5%). Among APAs-positive subjects, antibodies recognizing somatotrope cells were more common in acromegaly cases than in healthy controls (3/4 vs. 0/113, P < 0.0001), but had similar frequencies in NFPA (2/8) and prolactinomas (1/3). APAs are more frequently found in patients with pituitary adenomas than healthy subjects, with no significant difference among the tumor types studied. GH-secreting cells could represent a target of the autoimmune response.

The Growth Hormone-Insulin-like Growth Factor Axis in Glycogen Storage Disease Type 1: Evidence of Different Growth Patterns and Insulin-like Growth Factor Levels in Patients with Glycogen Storage Disease Type 1a and 1b

To investigate the growth hormone (GH)-insulin-like growth factor (IGF) system in patients with glycogen storage disease type 1 (GSD1). This was a prospective, case-control study. Ten patients with GSD1a and 7 patients with GSD1b who were given dietary treatment and 34 sex-, age-, body mass index-, and pubertal stage-matched control subjects entered the study. Auxological parameters were correlated with circulating GH, either at basal or after growth hormone releasing hormone plus arginine test, insulin-like growth factors (IGF-I and IGF-II), and anti-pituitary antibodies (APA). Short stature was detected in 10.0% of patients with GSD1a, 42.9% of patients with GSD1b (P = .02), and none of the control subjects. Serum IGF-I levels were lower in patients with GSD1b (P = .0001). An impaired GH secretion was found in 40% of patients with GSD1a (P = .008), 57.1% of patients with GSD1b (P = .006), and none of the control subjects. Short stature was demonstrated in 3 of 4 patients with GSD1b and GH deficiency. The prevalence of APA was significantly higher in patients with GSD1b than in patients with GSD1a (P = .02) and control subjects (P = .03). The GH response to the provocative test inversely correlated with the presence of APA (P = .003). Compared with levels in control subjects, serum IGF-II and insulin levels were higher in both groups of patients, in whom IGF-II levels directly correlated with height SD scores (P = .003). Patients with GSD1a have an impaired GH secretion associated with reference range serum IGF-I levels and normal stature, whereas in patients with GSD1b, the impaired GH secretion, probably because of the presence of APA, was associated with reduced IGF-I levels and increased prevalence of short stature. The increased IGF-II levels, probably caused by increased insulin levels, in patients with GSD1 are presumably responsible for the improved growth pattern observed in patients receiving strict dietary treatment.

Prevalence and Functional Significance of Antipituitary Antibodies in Patients with Autoimmune and Non-Autoimmune Thyroid Diseases

Circulating antipituitary antibodies (APA) are markers of autoimmune hypophysitis, which may cause deficient pituitary function. The prevalence of APA in autoimmune thyroid disorders (AITD) is uncertain. The aims of this study were 1) to evaluate APA prevalence in a large series of patients with AITD and non-AITD and 2) to investigate the functional significance of APA by assessing pituitary function in APA-positive patients. We conducted a health survey on consecutive AITD and non-AITD patients at a tertiary referral center (Department of Endocrinology, Pisa). Subjects, including 1290 consecutive patients with thyroid disorders (961 AITD and 329 non-AITD) and 135 controls, were enrolled in the study. APA (indirect immunofluorescence), free T(4), free T(3), TSH, and organ-specific autoantibodies were assayed in all patients. Functional pituitary evaluation was performed in most APA-positive patients. APA frequency was higher in AITD (11.4%) than in non-AITD (0.9%; P < 0.0001) patients; all control subjects had negative APA tests. APA were more frequently found in Hashimoto's thyroiditis (13%) than in Graves' disease (7.1%; P = 0.05). Of 110 APA-positive AITD patients, 20 (18.2%) had autoimmune polyglandular syndrome, whereas 90 (81.8%) had apparently isolated AITD. APA positivity increased percentage of autoimmune polyglandular syndrome in our series from 10.4 to 13.5%. Of 110 APA-positive patients, 102 were submitted to dynamic testing for functional pituitary assessment; 36 patients (35.2%) had mild or severe GH deficiency (GHD). No additional anterior pituitary hormone deficiencies were found; one patient had central diabetes insipidus. Pituitary abnormalities at magnetic resonance imaging were found in most APA-positive GHD patients. APA are frequently present in patients with AITD. Patients should be tested for APA because positive tests are associated with GHD.

Studies on circulating anti-pituitary antibodies in NIDDM patients.

The clinical significance of anti-pituitary antibodies (APA) was examined by enzyme-linked immunosorbent assay (ELISA) in individuals with non-insulin dependent diabetes mellitus (NIDDM). Serum samples were obtained from 150 NIDDM patients and 45 normal subjects. Urinary C-peptide (U-CPR) was also measured for the NIDDM patients. APA-positive serum was incubated with porcine pancreas, liver, kidney, or spleen powder and analyzed by immunoblot. The prevalence of APA was found to be significantly (P<0.05) higher in NIDDM patients (24.7%) than in the controls (6.7%) by ELISA. The index values for APA were inversely related to the levels of U-CPR (P<0.005). The levels of U-CPR were significantly (P<0.0001) lower and the prevalence of insulin deficiency was significantly (P<0.05) higher in NIDDM patients who were APA positive than in those who were APA negative. The presence of APA may therefore be related to reduced secretion of insulin in NIDDM patients. In Western blot analysis, preincubation of APA-positive sera with porcine pancreas powder prevented recognition of the 22-kD protein (APA). The possibility of a common autoantigenicity in the pancreas and the pituitary was indicated.

Antipituitary antibodies in patients with the primary empty sella syndrome.

The frequency of detection of serum antibodies against pituitary cells was determined in 32 patients with the primary empty sella syndrome. Antibodies reacting with corticotropin-secreting mouse AtT20 and PRL-secreting rat GH3 cells were found in 24 (75%) and 15 (47%), respectively, of the 32 patients; 14 patients (44%) had antibodies reacting with both cell lines. In patients with pituitary adenomas, the prevalence of antipituitary antibodies was significantly lower than in those with the empty sella syndrome; 1 of 9 acromegalic patients had antibodies reacting with GH3 cells, and 2 of 9 prolactinoma patients and 1 of 7 patients with nonfunctioning adenomas had antibodies reacting with both AtT20 and GH3 cells. Among 6 patients with idiopathic diabetes insipidus, 1 patient had antibodies reacting with AtT20 and GH3 cells, and 2 patients had antibodies reacting with either AtT20 or GH3 cells. None of 5 patients with established autoimmune diseases (3 with systemic lupus erythematosus and 2 with autoimmune adrenal failure) had antipituitary antibodies in their serum. These results suggest that pituitary antibodies may be related to the development of pituitary atrophy and the primary empty sella syndrome, and that the test may be clinically useful as a screening test for the empty sella syndrome.