Impact of different cut-off limits of peak GH after GHRH-arginine stimulatory test, single IGF1 measurement, or their combination in identifying adult patients with GH deficiency

The somatotroph pituitary gland function in high-aged multimorbid hospitalized patients with IGF-I deficiency

PURPOSE

It is unclear whether the age-related decline in the somatotropic axis stems from a reduced growth hormone (GH) production in the pituitary gland, or from a peripheral origin akin to an acquired GH resistance. With the help of a GHRH/arginine test, high-aged multimorbid hospitalized patients with IGF-I deficiency are to be tested to determine whether there is primarily a pituitary GH deficiency in the sense of a somatopause.

METHODS

Seventeen multimorbid patients (eleven men and six women) with a mean age of 82 years, with IGF-I concentrations below two standard deviations of 30-year-old men and women were identified. Patients suffered from a variety of common age-related stable diseases including coronary artery disease, chronic liver or kidney disease, chronic heart failure as well as acute conditions e.g., urosepsis or endocarditis. To assess the somatotropic axis they underwent a GHRH/arginine test. Results were evaluated using descriptive statistics.

RESULTS

In average, the peak concentration of GH after stimulation was 14.8 µg/L with a range from 2.76 to 47.4 µg/L. Taking into account both, gender and BMI (with a mean of 26.5 kg/m²) for each participant, the pituitary gland was adequately stimulated in 16 out of the 17 patients. No patient reported common side effects related to the GHRH/arginine test.

CONCLUSION

The somatotroph pituitary gland retains its secretory capacity in the advanced aged. Therefore, age does not seem to be the driving pacemaker for the functional decline of the somatotropic axis within the aged population.

GH provocative tests stimulate the growth in children with idiopathic short stature

CONTEXT

Growth hormone (GH) deficiency in a child with short stature is diagnosed by GH secretion provocative tests. When the test response is considered adequate, the short stature is considered idiopathic (ISS).

OBJECTIVE

To determine the effect of GH provocative tests on the growth rate in children with idiopathic short stature.

DESIGN

Children with short stature with a normal response to at least one GH provocative test were enrolled. Height and growth velocity were measured prior to and after stimulus tests during the follow-up.

METHODS

Height, mid-parental height, body weight, and body mass index were measured. The height and growth rate were converted to percentiles and Standard Deviation Scores (SDS) using reference ranges standardized by age and sex. GH provocative tests employed arginine or clonidine as secretagogues.

RESULTS

Fourty-six children of both genders were enrolled. In thirty-six children, height was measured at the time of testing and on an average time prior to and after the tests of 210 days and 180 days respectively. After testing the children displayed a 3.4-fold increase in their estimated 90-day growth rate. The median (inter-quartile range, IQR) 90 days growth of children pre-and post-tests were 0.7 (0.2-1.0) cm and 2.4 (1.7-3.1) cm respectively with a mean 3,4-fold increase (p < 0.0001). The median (IQR) 90 days growth of children pre- and post-tests calculated as standard deviation scores (SDS) were -4.0 (-5.4--2.1) SDS and 0.1 (-1.9-1.4) SDS respectively (p < 0.0001). Ten children with ISS were observed for about 5 months before the GH provocative tests. A small increase in the growth rate was seen only in 2 out of 10 children before testing while it increased in all of them after the tests. The difference in the median growth rate at the first and the second observation was not significant (p = 0.219).

CONCLUSIONS

Two sequential somatotropic axis provocative tests increase the growth rate in children with idiopathic short stature. The duration of this effect is yet to be determined.

Diagnosis of GH Deficiency Without GH Stimulation Tests

Growth hormone deficiency (GHD) is the most commonly affected pituitary hormone in childhood with a prevalence of 1 in 4000-10000 live births. GH stimulation testing (GHST) is commonly used in the diagnostic workup of GHD. However, GHD can be diagnosed in some clinical conditions without the need of GHST. The diagnosis of GHD in newborns does not require stimulation testing. Likewise infants/children with delayed growth and/or short stature associated with neuroradiological abnormalities and one or more additional pituitary hormone deficiencies may not need GHST. This review summarizes the current evidence on the diagnosis of GHD without stimulation tests.

IGF1 for the diagnosis of growth hormone deficiency in children and adolescents: a reappraisal

A number of studies have evaluated the role of IGF1 measurement in the diagnosis of growth hormone deficiency (GHD). This study aimed to evaluate the accuracy and the best cut-off of IGF1 SDS in the diagnosis of GHD in a large cohort of short children and adolescents. One-hundred and forty-two children and adolescents with GHD ((63 organic/genetic (OGHD), 79 idiopathic (IGHD)) and 658 short non-GHD children (median age 10.4 years) were included in the analysis. The two groups were subdivided according to age (G1 <6, G2 6 <9, G3 9 <12, G4 ≥12) and to pubertal status. Serum IGFI was measured by the same chemiluminescence assay in all samples and expressed as age- and sex-based SDS. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal IGF1 SDS cut-off and the diagnostic accuracy. Median IGF1 SDS was significantly lower in the GHD than in non-GHD patients. The area under the curve (AUC) was 0.69, with the best IGF1 cut-off of -1.5 SDS (sensitivity 67.61%, specificity 62.62%). The AUC was 0.75 for OGHD and 0.63 for IGHD. The accuracy was better in the pubertal (AUC = 0.81) than the prepubertal group (AUC = 0.64). In our cohort, IGF1 measurement has poor accuracy in discriminating GHD from non-GHD. Our findings confirm and reinforce the belief that IGF1 values should not be used alone in the diagnosis of GHD but should be interpreted in combination with other clinical and biochemical parameters.

Diabetes mellitus induced by somatostatin analogue therapy is not permanent in acromegalic patients

CONTEXT

Therapy with somatostatin analogues (SSAs) may have deleterious effects on glucose metabolism in patients with acromegaly, often leading to the development of diabetes mellitus (DM).

AIM

The aim of the study was to evaluate whether DM, developed during therapy with SSAs, may revert after drug withdrawal and cure of acromegaly with pituitary adenomectomy.

DESIGN

Retrospective cohort study, in a tertiary referral centre.

PATIENTS

Eighteen acromegalic patients without DM at the diagnosis of acromegaly treated with SSAs as a primary therapy, and then cured by pituitary adenomectomy.

METHODS

Endocrine status and glucose homeostasis were evaluated at diagnosis of acromegaly and at least every 6 months during SSA therapy. At each visit, patients were classified into one of the following classes: normal glucose tolerance, prediabetes, overt diabetes.

RESULTS

Median follow-up after starting SSAs therapy was 69 months (IQR 54.75-132.25). During SSA therapy, all patients had controlled acromegaly defined by normal serum IGF1 concentrations for the age. Of the 13 euglycaemic patients at diagnosis, three developed prediabetes and three diabetes, whereas, of the five prediabetic patients at diagnosis, two worsened to overt diabetes and three remained in the prediabetic range (P = 0.04). After curing acromegaly with pituitary adenomectomy and subsequent SSA withdrawal, prediabetes reverted in five of six patients, and diabetes in all five patients (three reverted to euglycaemia, while two reverted to prediabetes) (P = 0.01).

CONCLUSIONS

In acromegalic patients with controlled disease, changes in glycaemic status induced by SSAs are not permanent.

Treatment of adult growth hormone deficiency with human recombinant growth hormone: an update on current evidence and critical review of advantages and pitfalls

Adult-onset growth-hormone (GH) deficiency (GHD) is a rare disorder, which most commonly results from pituitary or peripituitary tumors and their treatment, and is characterized by alterations in body composition, carbohydrate and lipid metabolism, bone mineral density, cardiovascular risk profile and quality of life, all of which may contribute to an increased morbidity and mortality. Since recombinant human GH (rhGH) became available in 1985, several studies have provided evidence of its beneficial effects, despite the potential risk of developing adverse effects, and much clinical experience has been accumulated. However, in adults, the precise therapeutic role of GH replacement therapy and the individual response to it remains highly variable and is still a matter of debate. In this article, we present a critical review of the available evidence on rhGH replacement therapy in GHD adults, emphasizing the pitfalls clinicians encounter in the diagnosis of GHD and monitoring of rhGH replacement therapy. We will cover all the relevant aspects regarding the potential usefulness of GH treatment, including the hot topic of mortality.

Diabetes insipidus is an unfavorable prognostic factor for response to glucocorticoids in patients with autoimmune hypophysitis

INTRODUCTION

Autoimmune hypophysitis (AH) has a variable clinical presentation and natural history; likewise, its response to glucocorticoid therapy is often unpredictable.

OBJECTIVE

To identify clinical and radiological findings associated with response to glucocorticoids.

DESIGN AND METHODS

12 consecutive patients with AH, evaluated from 2008 to 2016. AH was the exclusion diagnosis after ruling out other pituitary masses and secondary causes of hypophysitis. Mean follow-up time was 30 ± 27 months (range 12-96 months).

RESULTS

MRI identified two main patterns of presentation: global enlargement of the pituitary gland or panhypophysitis (n = 4, PH), and pituitary stalk abnormality only, or infundibulo-neuro-hypophysitis (n = 8, INH). Multiple tropin defects were more common in PH (100%) than those in INH (28% P = 0.014), whereas diabetes insipidus was more common in INH (100%) than that in PH (50%; P = 0.028). All 4 PH and 4 out of 8 INH were treated with glucocorticoids. Pituitary volume significantly reduced in all PH patients (P = 0.012), defective anterior pituitary function recovered only in the two patients without diabetes insipidus (50%) and panhypopituitarism persisted, along with diabetes insipidus, in the remaining 2 (50%). In all INH patients, either treated or untreated, pituitary stalk diameter reduced (P = 0.008) but diabetes insipidus persisted in all.

CONCLUSIONS

Glucocorticoid therapy may improve anterior pituitary function in a subset of patients but has no effect on restoring posterior pituitary function. Diabetes insipidus appears as a negative prognostic factor for response to glucocorticoids.

Pitfalls of insulin-like growth factor-i and growth hormone assays

Accurate measurement of growth hormone (GH) and insulin-like growth factor-I (IGF-I) are the key to correct diagnosis of acromegaly and GH deficiency. Unfortunately, there is much variation involved when these hormones are measured at different sites and using different assay methods. There is an ongoing global effort to standardize the measurement process to obtain more comparable results in the future. This review discusses common pitfalls in the measurement of GH and IGF-I and guides laboratories in their analyses of these hormones.

Serum factors associated with precancerous colonic lesions in acromegaly

BACKGROUND

Insulin, 25-hydroxy vitamin D3 [25(OH)D3] and folate have been differently associated with a risk of colonic neoplasms in the general population. Acromegalic patients have an increased risk of colorectal tumors and an association between fasting insulin concentrations and colonic lesions has been reported. However, it is unknown whether insulin, 25(OH)D3, folate, and homocysteine interact to determine the risk of colonic tumors in acromegaly.

AIM

To investigate whether serum insulin, 25(OH)D3, folate, and homocysteine concentrations were associated with precancerous colonic lesions in acromegalic patients.

MATERIAL AND METHODS

A cohort of 146 consecutive acromegalic patients was evaluated for colonoscopy findings and fasting insulin, 25(OH)D3, folate, and homocysteine levels. A preliminary study was conducted in 9 naïve acromegalic patients to evaluate the effect of somatostatin analogues (SSA) on serum levels of those factors.

RESULTS

Insulin reduced during SSA whereas the other factors did not change. In the cohort study, colonic lesions (14 adenomas; 32 hyperplastic polyps) were detected in 46 patients. Fasting insulin, 25(OH)D3, folate, and homocysteine levels did not differ in patients with or without colonic adenomas. High folate levels were associated with a lower risk of developing precancerous colonic lesions at the multivariate analysis, when corrected by age, gender, disease activity and SSA therapy.

CONCLUSIONS

Serum insulin, 25(OH)D3 and homocysteine serum concentrations do not seem to influence the development of precancerous colonic lesions in acromegalic patients, while higher folate levels may be associated with a lower risk of colonic lesions.

Effects of medical therapies for acromegaly on glucose metabolism

OBJECTIVE

Abnormalities of glucose metabolism are common findings of acromegaly. However, robust evidence on whether therapy with somatostatin analogs (SSAs) or pegvisomant (PEG) differently affects glucose metabolism is lacking. The purpose of this study was to evaluate the effects of therapy with SSAs, PEG, or their combination on glucose metabolism in a large series of acromegalic patients.

DESIGN

This was a historical-prospective study. Among 50 consecutive acromegalic patients under SSA therapy, acromegaly in 19 patients was controlled. PEG used in combination with SSA therapy allowed the control of acromegaly in the remaining 31 patients and was then continued as monotherapy in 18 patients.

METHODS

The following parameters were evaluated at the diagnosis of acromegaly and during DIFFERENT TREATMENTS: fasting plasma glucose (FPG) and insulin concentrations, insulin sensitivity (QUICK-I), homeostasis model assessment of insulin resistance (HOMA2-IR), and plasma glucose and insulin concentrations during the oral glucose tolerance test (OGTT). Comparison was made using analysis for paired data.

RESULTS

Insulin resistance improved when acromegaly was controlled with therapy with SSAs, PEG, or SSA+PEG. However, FPG concentrations were higher during SSA therapy (alone or combined with PEG) than at the diagnosis of acromegaly, even when corrected for disease activity, whereas they were reduced during PEG therapy. Mean glucose concentrations during the OGTT were higher in patients receiving SSA therapy than in those receiving PEG therapy. In addition, the prevalence of diabetes or impaired glucose tolerance was higher during SSA therapy than at diagnosis or during PEG therapy and was not influenced by disease control.

CONCLUSIONS

Medical therapies for acromegaly reduce insulin resistance and increase insulin sensitivity; on the contrary, glucose indexes may be differently affected by SSA or PEG therapy.

Pituitary autoimmunity in patients with diabetes mellitus and other endocrine disorders

OBJECTIVE

Pituitary autoimmunity is often found in association with other endocrine autoimmune or non-autoimmune diseases. Aim of the study was to assess the prevalence of serum pituitary antibodies (PitAb) in patients with Type 1 diabetes mellitus (T1DM) or Type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

In this casecontrol study 111 patients with T1DM, 110 patients with T2DM, and 214 healthy controls were enrolled in a tertiary referral center. Pituitary, thyroperoxidase, thyroglobulin, 21-hydroxylase, and parietal cell antibodies were assessed in all cases. Endocrine function was further assessed by basal hormone measurement and by dynamic tests, as well as a pituitary magnetic resonance imaging (MRI) was performed in those patients found positive for PitAb.

RESULTS

PitAb prevalence was higher in T1DM (4 out of 111, 3.6%) than in T2DM (0 out of 110, p=0.045) and in healthy subjects (1 out of 214, 0.5% p=0.029). Prevalence of other autoimmune diseases was significantly higher in patients with T1DM (45 out of 111, 40.5%) when compared with patients with T2DM (18 out of 110 T2DM, 16.3%, p<0.001). Patients with T1DM and PitAb positivity were found with a pituitary lesion at MRI in 2 cases and pituitary dysfunction in one case.

CONCLUSIONS

A significant association between pituitary autoimmunity and T1DM was found, in particular in subjects with one or more other endocrine autoimmune diseases.