Goiter and impairment of thyroid function in acromegalic patients: basal evaluation and follow-up

Thyroid Disorders in Saudi Patients With Acromegaly: A Tertiary Care Center Experience

Background Acromegaly is a rare disease that is frequently associated with thyroid diseases. The exact prevalence of goiter and thyroid dysfunction remains uncertain. Objectives This study aims to provide a comprehensive description of the clinical, morphological, and biochemical features of thyroid disorder in Saudi patients with acromegaly and to establish its correlation with the activity and duration of the disease. Methods This retrospective study involved patients who were diagnosed with acromegaly during the period 2006-2023 in an outpatient endocrine clinic at a tertiary hospital. Results A total of 40 patients with acromegaly (27 males and 13 females) were identified and included in the analysis, with a mean age of 46.78 ± 13.76 years and an estimated duration of disease of 8.08 ± 6.43 years. Goiter was diagnosed in 28 patients (70.0%), including multinodular goiter (MNG) (70.0%), solitary thyroid nodules (14.2%), and thyroid cysts (14.2%). Primary hypothyroidism was present at 40.0%. Goiter was not correlated with estimated insulin-like growth factor 1 (IGF-1) levels or disease duration. In 40 patients with nodular goiter, fine needle biopsies were performed in six cases; five nodules were benign, and one nodule was a follicular lesion of unknown significance (Bethesda III). Conclusions The patients with acromegaly have a high prevalence of nodular thyroid disorders and thyroid dysfunction. No cases of thyroid cancer were found in our study. The periodic ultrasonography assessment of the thyroid is needed for evaluating patients with acromegaly.

GH Deficiency and Replacement Therapy in Hypopituitarism: Insight Into the Relationships With Other Hypothalamic-Pituitary Axes

GH deficiency (GHD) in adult patients is a complex condition, mainly due to organic lesion of hypothalamic-pituitary region and often associated with multiple pituitary hormone deficiencies (MPHD). The relationships between the GH/IGF-I system and other hypothalamic-pituitary axes are complicated and not yet fully clarified. Many reports have shown a bidirectional interplay both at a central and at a peripheral level. Signs and symptoms of other pituitary deficiencies often overlap and confuse with those due to GH deficiency. Furthermore, a condition of untreated GHD may mask concomitant pituitary deficiencies, mainly central hypothyroidism and hypoadrenalism. In this setting, the diagnosis could be delayed and possible only after recombinant human Growth Hormone (rhGH) replacement. Since inappropriate replacement of other pituitary hormones may exacerbate many manifestations of GHD, a correct diagnosis is crucial. This paper will focus on the main studies aimed to clarify the effects of GHD and rhGH replacement on other pituitary axes. Elucidating the possible contexts in which GHD may develop and examining the proposed mechanisms at the basis of interactions between the GH/IGF-I system and other axes, we will focus on the importance of a correct diagnosis to avoid possible pitfalls.

DECREASE IN ACROMEGALY-ASSOCIATED THYROID ENLARGEMENT AFTER NORMALIZATION OF IGF-1 LEVELS: A PROSPECTIVE OBSERVATION AND IN VITRO STUDY

Objective: Goiter occurs at high frequency in acromegaly patients. Whether normalization of insulin-like growth factor 1 (IGF-1) levels could decrease goiter and thyroid volume remains unclear. Methods: Thyroid hormone levels and ultrasound measurements were assessed in 101 acromegaly patients, compared with 108 patients with nonfunctioning pituitary adenoma (NFPA) and 55 healthy controls. Thirty-four acromegaly patients underwent repeat evaluation 1 year post-transsphenoidal surgery. The effect of IGF-1 on thyroid cell proliferation, cell cycle, and apoptosis was evaluated in vitro. Results: Acromegaly patients showed larger thyroid volume than those with NFPAs (18.32 mL vs. 9.91 mL; P<.001) and healthy controls (18.32 mL vs. 9.63 mL; P<.001). Duration of acromegaly was shown to be independently associated with thyroid volume enlargement (B = 0.259; 95% confidence interval, 0.162 to 0.357) in multivariate analysis. At follow-up, the median thyroid volume decreased from 22.74 to 17.87 mL in the cured group (n = 20; P = .003), but the number of nodular goiters showed no significant change. Serum free thyroxine levels decreased from 13.76 to 10.08 pmol/L in the cured group (P = .006) but increased from 9.28 to 12.09 pmol/L in the active group (P = .013). Change in thyroid volume was significantly correlated with IGF-1 level (r = 0.37; P = .029). In vitro, IGF-1 time- and dose-dependently promoted proliferation and secretory function of thyroid cells by enhancing cell cycle shift from the G1/S to G2/M phase and suppressing apoptosis. Conclusion: Acromegaly-associated thyroid volume increase, but not nodular goiter, could be reversed in cured acromegaly. IGF-1 time- and dose-dependently promoted the proliferation and secretory function of thyroid cells. Abbreviations: CCK-8 = Cell Counting Kit-8; fT3 = free triiodothyronine; fT4 = free thyroxine; GH = growth hormone; IGF-1 = insulin-like growth factor 1; MRI = magnetic resonance imaging; NFPA = nonfunctioning pituitary adenoma; qRT-PCR = quantitative real-time-polymerase chain reaction; TSH = thyroid-stimulating hormone.

The effect of disease activity on thyroid nodules in patients with acromegaly

Nodular thyroid disease is a very common disorder in patients with acromegaly. Insulin-like growth factor-1 (IGF-1) is a thyroid growth factor, and there is a correlation between IGF-1 levels and thyroid volume (TV) in patients with acromegaly. There is no study investigating the impact of somatostatin analog (SSA) treatment on thyroid nodule volume in patients with acromegaly. We aimed to assess thyroid nodule volume change with SSA treatment in patients with persistent acromegaly. We retrospectively analyzed data from 108 consecutive patients with acromegaly who were followed up by our clinic after undergoing surgery between 2002 and 2014. Patients who were cured after surgery were excluded. We only selected 43 patients (21 males, 22 females, mean age 52.8 ± 11.9 years) who did not meet the criteria of remission postoperatively, who were treated with SSA for at least six months and had normal thyroid function. Patients were divided into three groups (well-controlled, controlled, and active) according to their IGF-1 and growth hormone (GH) levels. All patients underwent an evaluation of TV and total thyroid nodule volume (TTNV) by ultrasound. TTNV decreased significantly in patients with well-controlled acromegaly (0.44 [0.75] to 0.23 [0.73], p < 0.001). TTNV did not change in controlled patients (0.18 [1.28] to 0.13 [1.54], p = 0.959); however TTNV increased in patients with active acromegaly (0.77 [1.46] to 1.03 [1.88], p = 0.028). Successful medical treatment of patients with active acromegaly decreases thyroid nodule volume. Sustained exposure to IGF-1 may cause an increase in thyroid nodule volume in patients with acromegaly.

Evaluation of the natural course of thyroid nodules in patients with acromegaly

PURPOSE

To investigate the nodular thyroid disease (NTD) and the natural course of thyroid nodules in patients with acromegaly.

METHODS

138 patients with acromegaly (73 F/65 M), whose initial thyroid ultrasonography performed in our university hospital, were included in this study. The frequencies of NTD, papillary thyroid cancer (PTC) and associated factors on nodule formation were investigated at initial assessment. Patients who had NTD continued to follow-up (n = 56) were re-evaluated with a ultrasonography performed after a mean 7-years follow-up period. The nodule size changes were compared with the initial data and the factors affecting nodule growth were investigated.

RESULTS

The frequency of NTD was found 69%. Patients with NTD were older (p = 0.05), with higher baseline IGF-1%ULN (upper limit of normal) (p = 0.01). In patients with NTD, the majority had similar nodule size (45%), decreased nodule size in 30% and nodule growth in 25%. In patients with active acromegaly at last visit, nodule growth was more significant (p < 0.001). For one unit change in the IGF-1 levels, nodule growth increased by 1.01 folds and presence of active acromegaly disease was related with ninefolds increase in nodule growth. The frequency of PTC was 14% in patients with nodule growth and PTC was diagnosed 11% of all acromegalic patients.

CONCLUSION

Both NTD and nodule growth is more frequent in active acromegalic patients. Thyroid nodules may show dynamic changes according to the disease activity and nodule growth should be closely monitored due to the risk of malignancy in patients with active acromegaly disease.

Focus on GH deficiency and thyroid function

The relationships between GH system and hypothalamic-pituitary-thyroid axis are complex and not yet fully understood. The reported effects of GH administration on thyroid status of GHD patients have been remarkably divergent. This review will focus on the main studies aimed to clarify the effects of GH on thyroid function, firstly going through the diagnosis of central hypothyroidism and its possible pitfalls, then elucidating the possible contexts in which GHD may develop and examining the proposed mechanisms at the basis of interactions between the GH-IGF-I system and the hypothalamic-pituitary-thyroid axis.

The Clinical Values of Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor Binding Protein-3 Levels in Blood and Thyroid Nodules

AIM

Insulin-like growth factor-1 (IGF-1) is a potent mitogen for many cells. IGF-1 plays a role in the pathogenesis of various tumors with its mutagenic and antiapoptotic properties. The aim of this study was to determine both the serum and intranodular levels of IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) in patients with nodular thyroid diseases.

MATERIALS AND METHODS

In this study, 80 subjects who performed fine-needle aspiration biopsy (FNAB) were required in order to investigate the effects of serum and intranodular IGF-1 and IGFBP-3 in the pathogenesis of nodules. After performing FNAB, IGF-1 and IGFBP-3 levels were determined in blood and aspiration samples.

RESULTS

The serum levels of IGF-1 (232.8 ± 12.9 ng/ml) and IGFBP-3 (4.8 μg/ml) were found significantly higher than that of the intranodular IGF-1 (39.1 ng/ml) and intranodular IGFBP-3 levels (0.173 μg/ml) (p < 0.01). Intranodular levels of IGF-1 and IGFBP-3 were higher in subjects with multinodular thyroid gland than those of subjects with solitary nodules (p = 0.043). A positive correlation between the nodule size and the serum IGFBP-3 levels was detected (p = 0.042, r = 0.23).

CONCLUSION

This study demonstrated the possible role of both IGF-1 and IGFBP-3 in the growth and the formation of multinodularity of thyroid nodules.

The higher incidence of autoimmune thyroid disease in prolactinomas than in somatotrophinomas

OBJECTIVE

Many studies have shown that prolactin (PRL) plays an important role in autoimmune diseases. The aim of this study was to compare the current frequency of autoimmune thyroid disease (ATD) in prolactinomas with another type of functional pituitary adenoma (FPA), somatotrophinoma. Another aim of the study was to evaluate possible factors related to thyroid autoimmunity and the process of ATD in FPAs.

METHODS

We retrospectively evaluated the presence of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) and thyroid morphologic findings in our patients with FPA (78 with acromegaly and 83 with prolactinoma). The relationship of autoantibody positivity with baseline PRL levels, activity of acromegaly, and treatment of dopamine agonists (DA) and hypogonadism was also assessed. Patients with ATD and hypothyroidism due to autoimmune thyroiditis were also evaluated.

RESULTS

ATD (Hashimoto's thyroiditis) was detected more frequently in patients with prolactinoma than in patients with acromegaly (33% and 17%, respectively; p=0.01). Thyroid autoantibody positivity was found more frequently in females in the whole group (p=0.02) and in the acromegaly group (p=0.008). There was no difference according to sex among the patients with prolactinoma (p=0.800). ATD was found not to be related with baseline PRL levels, treatment of DA, and presence of hypogonadism (p=0.232, p=0.435, p=0.464, respectively) in the prolactinoma group, and activity of acromegaly, presence of hypogonadism in the acromegaly group (p=0.753, p=0.654, respectively). Autoimmune hypothyroidism was more frequent in the prolactinoma group than in the acromegaly group among patients with thyroid autoantibody positivity (p=0.004).

CONCLUSION

Thyroid autoantibodies should be evaluated both at the time of diagnosis and during the course of treatment in patients with prolactinoma, and thyroid function tests should be closely monitored in patients with autoantibody positivity.

Thyroid autoimmune disorders in patients with acromegaly

PURPOSE

Disorders of the hypothalamic-pituitary-thyroid axis are common in patients with acromegaly and thyroid enlargement is present in the majority of them. The exact prevalence of goiter in patients with acromegaly remains uncertain and the presence of thyroid autoimmunity has not been extensively evaluated so far.

METHODS

We retrospectively evaluated thyroid biochemical and morphological findings in 116 acromegalic patients who attended our hospital. Serum TSH, total thyroxine levels and anti-thyroid peroxidase (ATPO) antibodies were measured by standard ultrasensitive techniques in all the patients. Thyroid ultrasound was performed in 75 out of them. The antibody control group was composed by healthy Argentinean individuals who attended the blood bank of our hospital in whom ATPO antibodies were measured.

RESULTS

Twenty-nine out of the 116 acromegalic patients (25 %) showed elevated titers of thyroid antibodies (79 % were women and 21 % men). The control group had a 10 % prevalence of thyroid autoimmunity. The prevalence of goiter by ultrasound was 36 %, being more common in females (41 %) than in males (28 %). Thirty-five percent of patients who presented thyroid nodules and 44 % of patients with ultrasound diagnosed goiters had positive thyroid autoimmunity. There was no significant correlation between the presence of nodules and IGF-1 levels, duration of disease or age.

CONCLUSION

We found a high prevalence of thyroid autoimmunity in our patients with acromegaly as compared to the normal population. Thyroid autoimmunity seems to be an additional mechanism for the development of thyroid disorders in acromegaly.

Effects of GH replacement therapy on thyroid volume and nodule development in GH deficient adults: a retrospective cohort study

OBJECTIVE

Despite the well-known effects of GH/IGF1 signaling on the thyroid, few data are available on the risk of developing nodular goiter in hypopituitary subjects during GH replacement therapy (GHRT). We aimed to define the effects of GH therapy on thyroid volume (TV) and nodular growth.

DESIGN

The records of 96 subjects (47 males and 49 females, median age 48 years) with GH deficit (GHD) were investigated. Seventy also had central hypothyroidism (CH). At the time of our retrospective evaluation, median treatment duration was 5 years.

RESULTS

Pre-treatment TV was smaller in GHD patients than in healthy subjects (P=0.030). During GH treatment, TV significantly increased (P=0.016 for the entire group and P=0.014 in euthyroid GHD patients). Before starting GH therapy, 17 patients harbored thyroid nodules. During GH therapy, nodule size increased slightly in seven patients, and new thyroid nodules occurred in nine patients. Among the 79 patients without pre-existing thyroid nodules, 17 developed one or more nodules. There was no difference in the prevalence of CH in GHD patients with or without thyroid nodules (P=0.915; P=0.841, when patients with pre-therapy nodular goiter were excluded), the main predictor for nodule development being serum IGF1 (P=0.038).

CONCLUSIONS

GHRT is associated with TV's increase in GHD patients. Thyroid nodules developed in 27% of patients, mainly in relation to pre-therapy IGF1 levels, independently of normal or impaired TSH stimulation.

Thyroid diseases in patients with acromegaly

Acromegaly often involves the presence of different pathologies of the thyroid gland. Long-lasting stimulation of the follicular epithelium by growth hormone (GH) and insulin-like growth factor 1 (IGF-1) can cause disorders in thyroid function, an increase in its mass and the development of goitre. Acromegalic patients present most frequently with non-toxic multinodular goitre. Nodules are more prevalent in patients with active acromegaly. It has been suggested that then thyroid size increases and it can be reduced through treatment with somatostatin analogues. The relationship between thyroid volume and the level of IGF-1 and the duration of the disease is unclear. Each acromegalic patient requires a hormonal and imaging evaluation of the thyroid when the diagnosis is made, and an accurate evaluation during further observation and treatment. Although the data concerning the co-occurrence of acromegaly and thyroid cancer still remain controversial, it is particularly important to diagnose the patient early and to rule out thyroid cancer.

Risk of thyroid nodular disease and thyroid cancer in patients with acromegaly--meta-analysis and systematic review

Introduction

Acromegaly is a quite rare chronic disease caused by the increased secretion of growth hormone (GH) and subsequently insulin - like growth factor 1. Although cardiovascular diseases remains the most common cause of mortality among acromegalic patients, increased prevalence of malignant and benign neoplasms remains a matter of debate. The aim of this study is to evaluate the risk of thyroid nodular disease (TND) and thyroid cancer in patients with acromegaly.

Materials and Methods

PubMed, Cochrane Library, Scopus, Cinahl, Academic Search Complete, Web of Knowledge, PubMed Central, PubMed Central Canada and Clinical Key databases were searched to identify studies containing. Random–effects model was used to calculate pooled odds ratios and risk ratios of TND in acromegaly. Studies which not included control groups were systematically reviewed.

Results

TND was more frequent in acromegaly than in control groups (OR = 6.9, RR = 2.1). The pooled prevalence of TND was 59.2%. Also thyroid cancer (TC) proved to be more common in acromegalic patients (OR = 7.5, RR = 7.2), prevalence was 4.3%. The pooled rate of malignancy (calculated per patient) was equal to 8.7%.

Conclusions

This study confirms that both TND and TC occur significantly more often in acromegalic patients than in general population. These results indicate that periodic thyroid ultrasound examination and careful evaluation of eventual lesions should be an important part of follow-up of patients with acromegaly.

Prevalence of thyroid diseases in patients with acromegaly: experience of a Brazilian center

OBJECTIVES: Acromegaly is frequently associated with thyroid diseases. In this study, we evaluated the frequency of thyroid disorders in a series of acromegalic patients. SUBJECTS AND METHODS: We evaluated 106 acromegalic patients using thyroid ultrasonography (US) and measurements of GH, IGF-I, free T4, TSH and anti-thyroperoxidase antibody levels. IGF-I was expressed in mass units and age-related standard deviation scores (SD-scores). Fine-needle aspiration biopsy (FNAB) was performed on thyroid nodules with a diameter greater than one centimeter or with suspicious characteristics. RESULTS: Thyroid disorders were found in 75 patients. Eleven patients had diffuse goiter, 42 patients had nodular goiter, and 22 patients had unspecific morphological abnormalities. Four patients (3.8%) had thyroid carcinoma. Considering the patients with diffuse or nodular goiter, thyroid volume was greater in patients with active acromegaly, and was positively correlated with GH, IGF-I, and IGF-I SD-score. CONCLUSIONS: Our study confirmed that benign thyroid diseases are frequent in acromegalic patients. The prevalence of thyroid cancer was higher than in the overall population. We suggest that thyroid US should be routinely performed in patients with acromegaly.

The role of insulin-like growth factor 1 in the development of benign and malignant thyroid nodules

OBJECTIVE

This study aims to investigate the role of IGF-1 in the development of nodular thyroid disease.

MATERIAL AND METHODS

A total number of 100 consecutive patients operated for nodular thyroid disease in our institution were included in this prospective study. In addition to classical pathological examinations, nodules and extranodular healthy tissues were sampled and immunochemically stained for IGF-1. The materials were independently evaluated using an Allred Scoring System ranging from 0 to 8. If the score was ≥1, the tissue was accepted as IGF-1 positive.

RESULTS

IGF-1 positivity was observed in 88% and 58% of the samples obtained from nodules and extranodular healthy tissues, respectively. Allred 8-unit scores were higher in benign nodules (n=89; 4.1±2.3) and papillary carcinomas (n=7; 6.7±1.3), than in extranodular healthy tissues in the same patients (2.3±2.3 and 3.3±1.9, respectively); and higher in papillary carcinomas than in benign nodules, when the scores were compared to each other (p<0.01 for all comparisons).

CONCLUSIONS

Allred 8-unit scores for IGF-1 increase in the presence of benign thyroid nodules, papillary cancer. The results of our study support the findings of previous studies demonstrating the role of IGF-1 in the development of thyroidal nodules.

Effects of depot growth hormone replacement on thyroid function and volume in adults with congenital isolated growth hormone deficiency

BACKGROUND

Conflicting data exist on the effects of GH replacement therapy (GHRT) on thyroid function and thyroid volume (TV) in GH-deficient (GHD) patients.

AIM

The aim of this study was to assess the effects of GHRT on thyroid function and TV in adults with congenital lifetime isolated GHD (IGHD).

SUBJECTS AND METHODS

We studied 20 GH-naïve adults with IGHD due to a homozygous mutation of the GHRH-receptor gene at baseline, after 6-month depot- GH replacement therapy (pGH), and 6-month washout (6mo). Total T(3), free T(4) (FT(4)), reverse T(3) (rT(3)), TSH, IGF-I, SHBG, and TV were measured; body surface area-corrected TV (CTV) was calculated.

RESULTS

IGF-I and T(3) increased pGH. T(3) levels remained elevated at 6mo. GHRT did not significantly change FT(4), rT(3), TSH, and SHBG. TV and CTV increased pGH and remained elevated at 6mo.

CONCLUSIONS

GHRT in IGHD adults caused an increase in serum T(3) levels and TV, suggesting an important role of the GH-IGF-I axis in thyroid function.

Association of thyroid gland volume, serum insulin-like growth factor-I, and anthropometric variables in euthyroid prepubertal children

CONTEXT AND OBJECTIVE

Few studies have focused on the interrelation between thyroid size, anthropometric variables, and IGF-I in adults, but such data are lacking for children. We have investigated thyroid gland volume and several hormonal and anthropometric variables in prepubertal children.

DESIGN AND PARTICIPANTS

A total of 859 prepubertal euthyroid Danish children aged 4-9 yr underwent a thorough clinical investigation, including anthropometrical measurements and determination of TSH, thyroid hormones, autoantibodies, urinary iodine excretion, and thyroid volume (TV) by ultrasound. Longitudinal growth data from birth were available.

RESULTS

TV increased significantly with age (r = 0.487; P < 0.001). Mean TV +/- sd for different age groups were as follows: 4 yr, 2.2 +/- 1.4 ml; 5 yr, 2.5 +/- 1.3 ml; 6 yr, 2.8 +/- 1.3 ml; 7 yr, 3.2 +/- 1.3 ml; 8 yr, 3.5 +/- 1.3 ml; 9 yr, 3.7 +/- 1.3 ml. We found a significant positive association between IGF-I and TV (P < 0.001). Furthermore, in multiple regression analyses, TSH (P < 0.013), free T(4) (P < 0.001), lean body mass (P < 0.001), and body surface area (P < 0.001) as well as other anthropometrical measurements were identified as factors significantly associated with TV. Family history of thyroid disease and presence of incidental abnormal ultrasound findings were also positively associated with TV (P = 0.025 and 0.022, respectively).

CONCLUSIONS

In our cohort of prepubertal Danish children, the GH/IGF-I-axis was positively correlated with thyroid size, suggesting a role in the regulation of thyroid growth. Moreover, anthropometric measurements, in particular body surface area, were the best predictors of TV.

Insulin-like growth factor-1 is essential to the increased mortality caused by excess growth hormone: a case of thyroid cancer and non-Hodgkin's lymphoma in a patient with pituitary acromegaly

The effects of growth hormone are mediated in part by stimulating the production of insulin-like growth factor-1. Insulin-like growth factor-1 has significant effects on cell proliferation and differentiation, it is a potent mitogen, and it is a powerful inhibitor of programmed cell death (apoptosis). Insulin-like growth factor-1 also has a well-established role in the transformation of normal cells to malignant cells. Case reports on a possible association between elevated growth hormone and cancer risk in a variety of patient groups have been published. Here, we describe clinical and laboratory findings for a patient with acromegaly who first developed thyroid cancer, and then, in the follow up period, probably due to poorly controlled insulin-like growth factor-1 levels, developed a large cell non-Hodgkin's lymphoma. A search revealed that a case with these peculiarities had not previously been reported.

Association between serum insulin-like growth factor-I levels and thyroid disorders in a population-based study

OBJECTIVE

There is current debate on whether serum IGF-I levels are associated with thyroid disorders. The aims of the present study were: 1) to investigate possible associations between serum IGF-I levels and thyroid disorders and 2) to analyze the role of serum IGF binding protein (IGFBP)-3 and TSH levels for these associations.

DESIGN

This was a cross-sectional Study of Health in Pomerania.

SETTING

The study was conducted in the general population of northeast Germany.

SUBJECTS

The study population comprised 3662 subjects (1746 women) without history of thyroid disorders.

INTERVENTIONS

No interventions have been performed.

MAIN OUTCOME MEASURES

Goiter and thyroid nodules were determined by ultrasound. Serum TSH levels less than 0.25 mIU/liter were considered decreased.

RESULTS

Adjusted for major confounders and risk factors for thyroid disorders, subjects with serum IGF-I levels above the upper tertile had higher odds for goiter relative to subjects with serum IGF-I levels below the lower tertile [odds ratio (OR) 1.67; 95% confidence interval (CI) 1.24-2.26 in women; OR 2.04; 95% CI 1.55-2.68 in men]. A similar association was present for thyroid nodules in men (OR 1.64; 95% CI 1.17-2.32) and for decreased serum TSH levels in women (OR 1.65; 95% CI 1.00-2.69). Serum IGFBP-3 levels were not associated with thyroid disorders and did not represent effect modifiers for the association between serum IGF-I levels and the endpoints.

CONCLUSIONS

We conclude that high serum IGF-I levels are associated with goiter. Whereas high serum IGF-I levels are also related to thyroid nodules in men, they are related to decreased serum TSH levels in women. Serum IGFBP-3 and TSH levels did not modulate these associations.

Thyroid morphology and function in adults with untreated isolated growth hormone deficiency

OBJECTIVE

GH influences thyroid function and anatomy. Although goiter is frequent in acromegalic patients, the effects of GH deficiency (GHD) are difficult to assess, because hypopituitaric subjects who lack GH often also have a partial or complete deficit of TSH.

STUDY DESIGN

We studied thyroid morphology and serum levels of thyroid hormones in adult members of a large Brazilian kindred with untreated isolated GHD due to a homozygous mutation in the GHRH receptor gene (GHRHR; nine men and 15 women; GHD group) and compared them to subjects heterozygous for the same mutation (eight men and 10 women; HET group) and subjects homozygous for the wild-type allele [seven men and 11 women; control (CO) group].

RESULTS

GHD subjects had a smaller thyroid volume (TV) than HET and CO. The TV of the HET group was intermediate between those of the GHD and CO groups. When TV was corrected by body surface area, it remained smaller in the GHD and HET groups than in the CO group, but the difference between GHD and HET groups disappeared. The GHD group had lower serum T3 levels than the CO group and higher free T4 levels than HET and CO groups.

CONCLUSIONS

Individuals with severe untreated GHD due to a homozygous GHRHR mutation and heterozygous carriers of the same mutation have smaller TV than normal subjects, suggesting that GH has a permissive role in the growth of the thyroid gland. In addition, GHD subjects have reduced serum total T3 and increased serum free T4, suggesting a reduction in the function of the deiodinase system.

Acromegalia e doença tiroideana: prevalência de câncer de tireóide

A relação entre câncer e acromegalia tem sido objeto de estudo há muitos anos. A partir de um caso de carcinoma diferenciado de tireóide em um de nossos pacientes acromegálicos, estudamos uma série de 100 outros acromegálicos e encontramos dois outros casos de câncer de tireóide, descritos neste trabalho. A partir daí, levantamos os dados da literatura sobre esta última associação e sua possível patogênese. A prevalência de patologias tireoidianas é aumentada dentre os acromegálicos, às custas, principalmente, do bócio nodular. Esta associação será abordada, assim como a relação entre o fator de crescimento insulina símile I (IGF-I) e câncer, numa tentativa de entender melhor seu significado frente aos nossos casos. Nós concluímos que seria prudente realizar exame ultrassonográfico periódico em acromegálicos, seguido de Punção Aspirativa com Agulha Fina (PAAF) dos nódulos suspeitos.

High prevalence of differentiated thyroid carcinoma in acromegaly

OBJECTIVE

Acromegaly is a chronic disease caused by increased GH secretion and associated with a greater risk of developing both benign and malignant tumours. In the present study we evaluated the prevalence of thyroid disorders and thyroid malignancies in a series of acromegalic subjects.

DESIGN AND PATIENTS

We studied, retrospectively, a continuous series of 125 acromegalic patients referred to the Endocrinology Centres at the University Hospitals of Catania and Ferrara, Italy, over a 22-year period.

MEASUREMENTS

Diagnosis and management of acromegaly were based on standardized criteria. In all patients thyroid function and morphology were evaluated by serum free T4, free T3, TSH measurements and ultrasound scanning, respectively. Fine-needle aspiration biopsy (FNAB) was performed in all solid-mixed thyroid nodules of diameter greater than 1 cm. IGF-1 expression was assessed by semiquantitative immunohistochemical analysis in some patients with differentiated thyroid cancer.

RESULTS

Abnormal thyroid function was found in eight cases (6%). A diffuse or nodular goitre was present in 102 cases (82%). Thyroidectomy was performed in 17 patients. Histological examination revealed a differentiated thyroid cancer in seven of the patients. No significant association of thyroid cancer with GH or IGF-1 levels was found. Semiquantitative assessment of IGF-1 expression by immunohistochemistry revealed a more intense staining in thyroid cancer from acromegalic subjects than in papillary thyroid cancer from nonacromegalic subjects.

CONCLUSIONS

The frequency of thyroid disorders in our series of acromegalic subjects was similar to that previously observed in these patients. However, the prevalence of thyroid cancer was not only strikingly elevated (5.6%) in comparison to the estimated prevalence in the general population (0.093%), but it was even higher than that reported for acromegalic subjects. Sustained exposure to high serum IGF-1 levels is likely to play a role in the development of thyroid cancer in this disease. An additive role for the autocrine/paracrine action of locally produced IGF-1 is also possible. Our results suggest that thyroid function and morphology should be carefully monitored in all acromegalic patients.

Pituitary tumor endocrinopathies and their endocrine evaluation

Pituitary tumors, depending on their respective cell type, manifest various endocrinopathies. Prolactinomas may present as hypogonadism and galactorrhea and can be diagnosed by measuring morning prolactin levels. Gonadotropinomas rarely cause gonadal hyperstimulation, and dynamic thyrotropin-releasing hormone stimulation testing is often required to elicit a diagnostic gonadotropin and/or subunit secretory response. Acromegaly is a multisystemic debilitating disease for which early diagnosis and treatment are crucial. Diagnostic criteria include a lack of plasma growth hormone suppression during the oral glucose tolerance test and elevation of age- and sex-matched insulin growth factor-1 levels. Patients harboring corticotropin-secreting adenomas characheristically present with signs and symptoms of hypercortisolism. Inferior petrosal sinus sampling for corticotropin may be required for microadenoma localization. Thyrotropinomas produce inappropriate thyrotropin (TSH) secretion and hyperthyroidism. The new third-generation TSH assay has improved the rate of detection of these lesions at an earlier stage.

Submandibular salivary gland volume is increased in patients with acromegaly

OBJECTIVE

Acromegaly is characterized by an enlargement of various organs. The aim of the present study was to evaluate whether acromegalic patients have an increased volume of submandibular salivary glands.

DESIGN AND SUBJECTS

Prospective study on 40 consecutive acromegalic patients (18 male, 22 female; mean age +/- SD, 50 +/- 13 years, range 22-74 years) submitted to submandibular salivary gland ultrasound. Among acromegalic patients, 15 had active and untreated disease (Acro-U), 13 were under long-acting somatostatin analogue therapy (Acro-SA), 12 were in remission after surgery (Acro-R). Two hundred subjects (90 male, 110 female, mean age +/- SD, 50 +/- 11 years, range 23-74 years) matched for age, sex and body mass index served as controls.

MEASUREMENTS

Submandibular salivary gland volume was measured in all acromegalic patients and normal subjects by ultrasound and calculated by the ellipsoid model. Serum GH and IGF-I concentrations were measured in all subjects.

RESULTS

Acro-U patients had higher serum IGF-I levels (691 +/- 235 microg/l) than Acro-R (174 +/- 74 microg/l), Acro-SA (436 +/- 239 microg/l) or controls (151 +/- 66 microg/l) (P < 0.0001, P = 0.008, P < 0.0001, respectively). The mean submandibular salivary gland volume was higher in acromegalic patients than in controls: Acro-U 18.1 +/- 3.3 ml, Acro-SA 16.2 +/- 3.3 ml, Acro-R 15.7 +/- 3.0 ml and controls 8.2 +/- 2.4 ml (P < 0.0001). Differences among subgroups of Acro patients were not significant. Enlargement of the submandibular salivary glands was present in 35/40 (87.5%) acromegalic patients. A positive correlation between serum IGF-I (P < 0.0001), GH (P < 0.0001) and submandibular salivary gland volume was found.

CONCLUSIONS

Acromegalic patients have an increased volume of submandibular salivary glands, independently of the activity of disease.

Prevalence of thyroid diseases in patients with acromegaly: results of an Italian multi-center study

Acromegaly is frequently associated with the presence of thyroid disorders, however the exact prevalence is still controversial. An Italian multicenter study was performed on 258 patients with active acromegaly (high levels of IGF-I and lack of suppression of serum GH levels below 2 microg/l after an OGTT). The control group was represented by 150 patients affected by non-functioning and PRL-secreting pituitary adenomas. Two hundred and two out of 258 acromegalic patients (78%) were affected by thyroid disorders with a significantly higher prevalence with respect to the control group (27%, p<0.0001). One hundred and three patients presented (39.9%) non-toxic nodular goiter, 46 (17.8%) non-toxic diffuse goiter, 37 (14.3%) toxic nodular goiter, 1 toxic diffuse goiter (0.4%), 12 (4.6%) Hashimoto's thyroiditis, 3 (1.2%) thyroid cancer. Two patients presented a co-secreting TSH pituitary adenoma. Thirty-six patients had been previously treated for various thyroid abnormalities. Among the 222 acromegalic patients never treated for thyroid disorders thyroid ultrasonography was performed on 194 subjects. Thyroid volume in patients with thyroid abnormalities was 28+/-17.5 ml (median 23) while it was 10.8+/-3.6 ml (median 10) in patients without thyroid disorders (p<0.0001). Thyroid volume was correlated with the estimated duration of acromegaly (r=0.7, p<000.1), but not with age or with serum GH, IGF-I and TSH concentrations. Thyroid volume was higher in acromegalic patients than in the above control population (23.5+/-16.9 ml vs 13.9+/-12.8 ml, p<0.0001). In 62 acromegalic patients 101 fine-needle biopsies of thyroid nodules were performed; 7 nodules were suspicious and the patients were submitted to thyroid surgery: papillary thyroid carcinoma was found in 3 patients. In conclusion, in a large series of acromegalic patients an increased prevalence of thyroid disorders (78%), particularly non-toxic nodular goiter, has been observed. Thyroid volume, evaluated by ultrasonography, was correlated to the estimated duration of acromegaly. Finally, the prevalence of thyroid carcinoma was slightly increased than in the general population.

Low TSH requirement and goiter in transgenic mice overexpressing IGF-I and IGF-Ir receptor in the thyroid gland

Through the cAMP signaling pathway, TSH stimulates thyroid follicular cell proliferation, differentiation, and function. Although the autocrine production of IGF-I in the thyroid gland suggests an important physiological function for this factor in these processes, the exact role of the IGF-I/IGF-I receptor system in vivo remains unclear. Although the mitogenic action of TSH requires the presence of IGF-I or insulin in primary culture of dog and human thyroid cells, IGF-I has an effect equal to and independent of the effect of TSH on cell proliferation in rat thyroid cell lines and may even be the main growth regulator in this case. To investigate the in vivo function of the IGF-I/IGF-I receptor system, transgenic mice overexpressing human IGF-I, IGF-I receptor, or both in the thyroid were generated. Adult transgenic mice did not present external signs of thyroid dysfunction, but mice overexpressing both transgenes had significantly increased gland weight and follicular lumen area. A decreased TSH level together with a slightly increased serum T(4) concentration and increased thyroidal iodine uptake were also observed, suggesting that IGF-I and IGF-I receptor stimulate thyroid function to some extent in vivo.