A nationwide attempt to standardize growth hormone assays

Coexistence of growth hormone, adrenocorticotropic hormone, and testosterone deficiency associated with coronavirus disease 2019: a case followed up for 15 months

Coronavirus disease 2019 (COVID-19) is associated with endocrine disorders, but their long-term clinical course remains unclear. We here report the 15-month clinical course for an individual with multiple endocrine disorders of the pituitary gland and testis likely triggered by COVID-19. A 65-year-old man with no history of endocrinopathy was admitted for acute COVID-19 pneumonia. Although his respiratory condition improved after administration of antiviral drugs, his blood pressure dropped suddenly to a preshock level and was refractory to vasopressors. The circulating adrenocorticotropic hormone (ACTH) and cortisol concentrations were low, and secondary adrenal insufficiency was suspected. Administration of hydrocortisone rapidly ameliorated the hypotension, and the patient was discharged taking 15 mg of hydrocortisone daily. An insulin tolerance test performed 3 months later revealed impaired ACTH, cortisol, and growth hormone (GH) responses, indicative of combined hypopituitarism. The patient also manifested symptoms of hypogonadism, and a hormonal workup suggested primary hypogonadism. At 12 months after discharge, GH and ACTH responses had recovered completely and partially, respectively. After another 3 months, basal ACTH and cortisol levels had been restored to the normal range and the patient discontinued hydrocortisone replacement without exacerbation of symptoms, although his hypogonadism persisted. The patient thus developed transient GH and ACTH deficiency that lasted for more than a year as well as persistent primary hypogonadism during intensive care for COVID-19. Certain prolonged symptoms of COVID-19 might be accounted for by such hormonal disturbance.

Demographic characteristics of children with growth hormone deficiency from 1996 to 2015 in Japan: 20 years of data from the foundation for growth science in Japan

Growth hormone (GH) deficiency (GHD) in children is a heterogeneous condition that includes several entities of various severities. GH treatment has been affected by various factors. Because comprehensive analyses for Japanese children with GHD over time are scarce, we investigated the baseline characteristics of patients with GHD at the start of GH treatment between 1996 and 2015 using data from the Foundation for Growth Science in Japan. During the registration period, 19,717 subjects were determined to be eligible for GH treatment as GHD. Overall analyses revealed that there were twice the number of male patients as female patients, and the etiology was idiopathic in 91.1%, central nervous system (CNS) tumor at the hypothalamus-pituitary area in 1.7%, CNS tumor distant from the hypothalamus-pituitary area in 0.68%, other tumors in 0.91%, congenital CNS malformations in 0.83%, and other diseases in 1.1% with their specific characteristics. The latest average age, height standard deviation score (SDS), insulin-like growth factor-1 SDS, and proportion of severe GHD at GH treatment initiation were 8.8 years, -2.76, -1.42, and 19.5%, respectively. The proportions of breech delivery and asphyxia gradually decreased, whereas that of caesarean section gradually increased during the registration period with the latest values of 2.2%, 4.9%, and 14.0%, respectively (all analyses: p < 0.0001). In contrast, the proportion of idiopathic GHD with breech delivery seemed to reach the lowest level among those with a birth year before 2000. This study identified the characteristics and changes of patients with GHD over 20 years.

History of GH treatment in Japan

In Japan, a pituitary-extracted human GH (phGH), Crescormon®, was approved for the treatment of pituitary dwarfism in 1975. The Study Group of Pituitary Dysfunction was organized by the Ministry of Health and Welfare (MHW) in 1973 and prepared the “Diagnostic Handbook: Pituitary Dwarfism” guidelines in 1974. Eligibility assessments for phGH treatment were conducted by the research group on pituitary dwarfism (later the Foundation for Growth Science [FGS] GH Treatment Eligibility Assessment Committee); however, there were 200–300 patients on the waiting list. GH treatment has been financially supported by the Grant-in-Aid Program for Chronic Diseases in Childhood, MHW, since 1974. In 1984, phGH was discontinued in the United States due to reports of the onset of Creutzfeldt–Jakob disease in patients treated with phGH. Japan approved the use of methionyl hGH in 1986 and recombinant hGH in 1988. As a result, the phGH disappeared from the market. The role of the Eligibility Assessment Committee of the FGS shifted to the provision of second opinions about diagnoses and treatment appropriateness. Since then, the indications for GH treatment of pediatric growth disorders have expanded to include other pediatric growth disorders such as Turner syndrome, achondroplasia/hypochondroplasia, etc.

Brain MRIs may be of low value in most children diagnosed with isolated growth hormone deficiency

OBJECTIVES

Brain MRIs are considered essential in the evaluation of children diagnosed with growth hormone deficiency (GHD), but there is uncertainty about the appropriate cut-off for diagnosis of GHD and little data about the yield of significant abnormal findings in patients with peak growth hormone (GH) of 7-10 ng/mL. We aimed to assess the frequency of pathogenic MRIs and associated risk factors in relation to peak GH concentrations.

METHODS

In this retrospective multicenter study, charts of patients diagnosed with GHD who subsequently had a brain MRI were reviewed. MRIs findings were categorized as normal, incidental, of uncertain significance, or pathogenic (pituitary hypoplasia, small stalk and/or ectopic posterior pituitary and tumors). Charges for brain MRIs and sedation were collected.

RESULTS

In 499 patients, 68.1% had normal MRIs, 18.2% had incidental findings, 6.6% had uncertain findings, and 7.0% had pathogenic MRIs. Those with peak GH<3 ng/mL had the highest frequency of pathogenic MRIs (23%). Only three of 194 patients (1.5%) with peak GH 7-10 ng/mL had pathogenic MRIs, none of which altered management. Two patients (0.4%) with central hypothyroidism and peak GH<4 ng/mL had craniopharyngioma.

CONCLUSIONS

Pathogenic MRIs were uncommon in patients diagnosed with GHD except in the group with peak GH<3 ng/mL. There was a high frequency of incidental findings which often resulted in referrals to neurosurgery and repeat MRIs. Given the high cost of brain MRIs, their routine use in patients diagnosed with isolated GHD, especially patients with peak GH of 7-10 ng/mL, should be reconsidered.

Dilemmas of growth hormone treatment for GH deficiency and idiopathic short stature: defining, distinguishing, and deciding

Worrisome growth can be a sign of underlying pathology but usually reflects healthy variation. It is often recognized through short stature, which is defined by arbitrarily separating height, a physical trait on a continuum, into "normal" and "abnormal." In some cases of worrisome growth, recombinant human growth hormone (rhGH) treatment is indicated to hasten growth/increase height. This review addresses the two most frequently treated indications for rhGH, growth hormone deficiency (GHD) and idiopathic short stature (ISS). A review of worrisome growth itself, of the history of GH treatment, of the blurry line between partial GHD and ISS, of the GH stakeholders, and of the outside pressures involved in these cases demonstrates the ambiguous platform upon which treatment decisions are made. The rhGH treatment decision process can be examined further by considering the three most impactful factors on parental height-related medical decision-making: treatment characteristics, child health, and psychosocial function. While it is important to note that treatment for classical GHD is uncontroversial and supported, treatment decisions for partial GHD and ISS are more complicated and require careful evaluation of both patient needs and the supporting evidence. As the rhGH community grows, physicians, parents, and patients are encouraged to engage in a shared decision-making process to navigate the many challenges facing the GH field. Although this review addresses GHD and ISS specifically, the issues discussed are often applicable to pediatrics as a whole.

Effects of Growth Hormone Treatment on Lipid Profiles

OBJECTIVES

To assess the effects of growth hormone (GH) on lipid profiles in children and whether the effect is pharmacological.

METHODS

The authors determined serum levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), and low-density lipoprotein cholesterol (LDL-C) every year during 3-y GH treatment in 48 GH deficient (GHD) short children and 22 children with short stature born small for gestational age (SGA).

RESULTS

The abnormally high levels of TC, non-HDL-C, and LDL-C showed a high frequency in GHD short children compared with epidemiological studies in Japan. The high prevalence of high level of TC was also shown in SGA short children. Three-year GH treatment decreased serum TC, non-HDL-C, and LDL-C levels in both patient groups.

CONCLUSIONS

GH treatment is clearly a pharmacological therapy in SGA short children and so may also be in GHD short children at the Japanese standard therapeutic dose. Taken together, GH improves lipid profiles, and its effect has the possibility of medical properties.

Continuing efforts to standardize measured serum growth hormone values in Japan

Determination of serum growth hormone (GH) levels is mandatory for diagnosis of GH deficiency and excess. In the present study, we, the Study Committee for GH and Its Related Factors, The Foundation for Growth Science, Japan measured GH values in serum samples using all the commercially available kits in Japan. Significant discrepancies in the GH values were observed among the kits in spite of using the unified recombinant human GH-based standards. To deal with the discrepancies, we established a formula using a linear structural relationship model and were able to standardize the GH values. We propose to use the formula to diagnose GH deficiency and excess in Japan.

Combined Growth Hormone and Thyroid-Stimulating Hormone Deficiency in a Japanese Patient with a Novel Frameshift Mutation in IGSF1

BACKGROUND

Recent reports have indicated that loss-of-function mutations in the immunoglobulin superfamily member 1 gene (IGSF1, OMIM 300888) cause congenital central hypothyroidism with macroorchidism.

METHODS

We conducted a next-generation sequencing-based comprehensive mutation screening for pituitary hormone deficiencies to elucidate molecular mechanisms other than anatomical abnormalities of the pituitary that might be responsible for multiple anterior hormone deficiency in a male patient who originally visited our institute complaining of short stature. He was born large for gestational age (4,370 g, +3.0 SD) after an obstructed labour. Endocrinological evaluation revealed growth hormone and thyroid-stimulating hormone deficiency. Magnetic resonance imaging showed a discontinuity of the pituitary stalk with an ectopic posterior lobe and a hypoplastic anterior lobe, likely explaining multiple anterior pituitary hormone deficiency.

RESULT

We identified a novel hemizygous IGSF1 mutation (c.1137_1138delCA, p.Asn380Glnfs*6) in the patient. In reviewing the literature, we noticed that all reported Japanese male IGSF1 mutation carriers were born larger than mean standards for gestational age (mean birth weight SD score of +2.0, 95% confidence interval 1.0-3.0).

CONCLUSION

This case suggests that more attention should be paid to intrauterine growth and birth history when patients are suspected of having an IGSF1 mutation.

Controversies in the diagnosis and management of growth hormone deficiency in childhood and adolescence

Growth hormone deficiency (GHD) is a rare but important cause of short stature in childhood with a prevalence of 1 in 4000. The diagnosis is currently based on an assessment of auxology along with supporting evidence from biochemical and neuroradiological studies. There are significant controversies in the diagnosis and management of GHD. Growth hormone (GH) stimulation tests continue to play a key role in GHD diagnosis but the measured GH concentration can vary significantly with stimulation test and GH assay used, creating difficulties for diagnostic accuracy. Such issues along with the use of adjunct biochemical markers such as IGF-I and IGFBP-3 for the diagnosis of GHD, will be discussed in this review. Additionally, the treatment of GHD remains a source of much debate; there is no consensus on the best mechanism for determining the starting dose of GH in patients with GHD. Weight and prediction based models will be discussed along with different mechanisms for dose adjustment during treatment (auxology or IGF-I targeting approaches). At the end of growth and childhood treatment, many subjects diagnosed with isolated GHD re-test normal. It is not clear if this represents a form of transient GHD or a false positive diagnosis during childhood. Given the difficulties inherent in the diagnosis of GHD, an early reassessment of the diagnosis in those who respond poorly to GH is to be recommended.

Prevalence of Simple Renal Cysts in Acromegaly

Objective Various organs are known to be affected by the comorbidities of acromegaly. However, the involvement of renal structural comorbidities, such as cysts, has so far remained largely unknown. In this single-center study, we aimed to determine the prevalence and factors associated with simple renal cysts in Japanese patients with acromegaly. Methods A total of 71 consecutive patients with acromegaly were analyzed, who all underwent abdominal ultrasonography at diagnosis between 1986 and 2012 at Kobe University Hospital. Results Of these 71 patients, 23 (32.4%) exhibited simple renal cysts. Acromegalic patients with renal cysts tended to be significantly older, had a higher prevalence of smoking- and higher nadir growth hormone (GH) levels during the oral glucose tolerance test (OGTT) than did those without renal cysts. A multivariate logistic regression analysis showed age, smoking, and nadir GH to be independent factors associated with renal cysts. Interestingly, the number of renal cysts positively correlated with both the basal GH levels and nadir GH levels during OGTT (r=0.66, p<0.05 and r=0.70, p<0.05, respectively). In addition, the mean diameter of renal cysts positively correlated with the systolic blood pressure (r=0.84, p<0.005). Conclusion This is the first report to show the prevalence of simple renal cysts in patients with acromegaly. Elevated nadir GH levels during OGTT were found to be associated with an increased risk of simple renal cysts. Therefore, an excessive secretion of GH may be related to the development of renal cysts.

The prevalence and associated factors of colorectal neoplasms in acromegaly: a single center based study

PURPOSE

Colorectal neoplasms are well known to be a complication in cases of acromegaly; however, data on the prevalence of colorectal neoplasms in Asian patients with acromegaly are limited. Further, the factors associated with colorectal neoplasms in cases of acromegaly are controversial. Therefore, we aimed to clarify the prevalence of and factors associated with colorectal neoplasms in Japanese patients with acromegaly in a single center.

METHODS

We analyzed consecutive 57 patients who had undergone full-length colonoscopy at the time of diagnosis at Kobe University Hospital between 1986 and 2012.

RESULTS

Of the 57 patients, 22 (38.6%), 18 (31.6%) and 3 (5.3%) patients were diagnosed with hyperplastic polyps, adenomas, and adenocarcinomas, respectively and the prevalence was significantly higher than in a historical control group, Chinese patients with irritable bowel syndrome (The odds ratio was 4.0, 8.7, and 17.5, respectively). The prevalence of adenocarcinomas was also significantly higher in these patients than in the general Japanese population (odds ratio 14.5). Patients with acromegaly who had colorectal neoplasms had longer disease duration than those without colorectal neoplasms. Of note, the area under the growth hormone (GH) concentration-time curve (GH AUC) during the oral glucose tolerance test was significantly higher in patients with adenocarcinomas than in those with no colonic lesion or those with hyperplastic polyps.

CONCLUSION

Japanese patients with acromegaly exhibited an increased risk of colorectal neoplasms, especially colorectal adenocarcinomas. An increased GH AUC was associated with an increased risk for colon adenocarcinomas in patients with acromegaly.

The harmonisation of growth hormone measurements: taking the next steps

For over 20 years differences in results of growth hormone (GH) measurement have been recognised as being significant enough to lead to misdiagnosis and inappropriate management of patients with GH-related disorders. Whilst issues of method standardisation, variable antibody specificity, use of different reporting units with different conversion factors, and interference from GH binding protein have been acknowledged as contributing to the discrepancies, inconsistent approaches to method harmonisation have hampered opportunities to enhance the evidence base for GH measurements. Amongst the first steps to be taken, international collaboratives recommended the universal adoption of the International Standard 98/547 and the reporting of results in mass units. Whilst inter-method variability may have improved over the last 10 years, clinically significant differences remain. A more recently recognised issue contributing to the discrepancies may be the differences in the matrix materials used by kit manufacturers to assign values to their calibrants. The establishment of an international harmonisation oversight group is recommended: its key roles to include identification of a commutable matrix reference material, assessing the clinical significance of assay interferents, the evaluation of liquid chromatography-mass spectrometry as a reference measurement procedure and the provision of acceptance criteria for the clinical application of GH methods.

Clinical features and therapeutic outcomes of acromegaly during the recent 10 years in a single institution in Japan

Untreated acromegaly is associated with a twofold to fourfold increased mortality risk compared to the population. Recently, new therapeutic modalities have been developed and may contribute to an improvement in treatment outcomes in patients with acromegaly. In the current study we determined the clinical features and recent therapeutic outcomes in patients with acromegaly. The initial symptoms, selected therapeutic modalities, and outcomes in 125 patients with acromegaly (M/F, 49/76, 19-86 years) who were admitted to our institution between 2001 and 2010 were analyzed using medical charts. The basal GH levels and IGF-I SD scores in the patients ranged from 0.17 to 90.21 μg/L and 1.9-13.6, respectively. Acral enlargement (face, hands, and feet) without overt complications was essential to the diagnosis in 49 % of the patients. In these cases, it required 5 years to establish the diagnosis of acromegaly after symptom onset. Twenty (16 %) and 13 (10 %) patients had diabetes mellitus and hypertension 6 years prior to the diagnosis of acromegaly, respectively. In 35 patients with microadenomas, the rate of controlled cases following transsphenoidal surgery was 93 %. In 90 patients with macroadenomas, the remission rate was 79 % with multidisciplinary treatment. In cases in which the tumor extended beyond the lateral tangent of the internal carotid artery (Knosp grade ≥3), the remission rate was 33-56 %. Improvements in surgical techniques and medical therapies may contribute to increased rates of controlled cases in patients with acromegaly, although advanced lateral extension of the tumor remains a critical determinant of the therapeutic outcome.

Novel compound heterozygous mutations of the growth hormone-releasing hormone receptor gene in a case of isolated growth hormone deficiency

OBJECTIVE

To elucidate the pathogenesis of isolated growth hormone (GH) deficiency in a Japanese girl without consanguinity.

DESIGN

A 2-year-old girl of height 77.2 cm (-3.0 SD for Japanese girls) was found to have an insulin-like growth factor (IGF)-1 level of 7 ng/mL and IGF binding protein-3 (IGFBP-3) level of 0.41 μg/mL. GH responded modestly to a series of pharmacological stimulants, increasing to 2.81 ng/mL with insulin-induced hypoglycemia, 3.78 ng/mL with arginine, and 3.93 with GH-releasing hormone (GHRH). Following direct sequencing of the GHRH receptor (GHRHR) gene, evaluation by the luciferase reporter assay, immunofluorescence study, and in vitro splicing assay with minigene constructs was conducted.

RESULTS

Novel compound heterozygous GHRHR gene mutations were identified in the patient. A p.G136V substitution elicited no luciferase activity increment in response to GHRH stimulation, with normal membranous expression. Splicing assay demonstrated that the IVS2+3a>g mutation would lead to aberrant splicing.

CONCLUSIONS

A case of isolated GH deficiency due to novel GHRHR gene mutations was identified.

Harmonization of growth hormone measurements with different immunoassays by data adjustment

BACKGROUND

The aim of our study was to evaluate the between-assay variability of commercially available immunoassays for the measurement of human growth hormone (hGH). In addition, we asked whether the comparability of the diagnosis of childhood onset growth hormone deficiency could be improved by adjusting hGH results by statistical methods, such as linear regression, conversion factors, and quantile transformation.

METHODS

In archived sera from 312 children and adolescents (age: 17 days-17 years) hGH values between 0.01 and 16.5 ng/mL were determined by using the following immunoassays: AutoDELFIA (PerkinElmer), BC-IRMA (Beckman-Coulter), ELISA (Mediagnost), IMMULITE 2000 (Siemens), iSYS (IDS), Liaison (DiaSorin), UniCel DxI 800 Access (BeckmanCoulter) and "In house"-RIA (Tübingen).

RESULTS

The assays differed in median hGH concentrations by as much as 5.44 ng/mL (Immulite), and as little as 2.67 ng/mL (BC-IRMA). The mean difference between assays ranged from 0.35 to 2.71 ng/mL, whereas several samples displayed differences up to 11.4 ng/mL. The best correlation (r=0.992) was found between AutoDELFIA and Liasion, the lowest (r=0.864) was between an in-house RIA and iSYS. The between-assay CV (mean ± SD) of values within the cut-off range was 24.3% ± 7.4%, resulting in an assay-dependent diagnosis of growth hormone deficiency (GHD) in more than 27% of patients. Yet, adjustment of this data by linear regression or a conversion factor reduced the CV below 14%, and the ratio of assay-dependent diagnoses below 8%. Using quantile transformation, the CV and ratio were reduced to 11.4% and <1%, respectively.

CONCLUSIONS

hGH measurements using different assays vary significantly. Linear regression, conversion factors, or particularly quantile transformation are useful tools to improve comparability in the diagnostic procedure for the confirmation of GHD in childhood and adolescence.

Effects of GH assay standardization on evaluation of treatment outcomes for acromegaly in Japan

In Japan, the growth hormone (GH) assay has been standardized since April 2005 through use of a uniform recombinant human GH (rhGH) standard. Since then, GH values measured using the rhGH standard have been approximately 40% lower than previous values measured using kit standards based on the WHO standards for hGH of pituitary origin. However, the Japanese criteria for evaluating treatment outcomes for acromegaly have remained the same: a nadir GH during a 75 g OGTT <1 µg/L is considered cured, 1≤GH<2.5µg/L is considered inadequately controlled, and ≥2.5 µg/L is considered poorly controlled, instead of these levels were lowered to 60%, i.e. from 1 to 0.6 µg/L for cured and from 2.5 to 1.5µg/L for inadequately controlled (termed as "newly proposed criteria" in this study). We investigated the effects of standardization of the GH assay on the evaluation of post-surgical disease activity in 50 patients with acromegaly (M/F 19/31, 21-72 yr.). Post-surgical nadir GH levels during OGTT were positively correlated with the IGF-I SD score 3 months after TSS. Five of 6 patients whose post-surgical nadir GH levels ranged between 0.6 and 1 µg/L had normal serum IGF-I levels 3 months after TSS. Rates of improvement in glucose metabolism did not differ when patients were classified based on the present criteria vs. the newly proposed criteria. In conclusion, the current Japanese remission criteria for acromegaly still accurately reflect post-surgical disease activity in most patients, though long-term observation is still required.

Dose-dependent changes in body composition during growth hormone (GH) treatment in Japanese patients with adult GH deficiency: a randomized, placebo-controlled trial

OBJECTIVE

A clinical study was carried out to investigate the efficacy and safety of two doses of GH treatment on adult growth hormone deficiency (AGHD) patients in Japan. Dose-responsiveness between GH doses and changes of body composition was examined.

DESIGN

A 24-week, randomized, placebo-controlled, double-blind clinical study in 96 Japanese AGHD patients followed by a 48-week, open-label, long-term study.

RESULTS

During the double-blind study, serum insulin-like growth factor (IGF)-I SDS and lean body mass increased and total fat mass and serum total cholesterol decreased similarly in both GH treated groups. Mean changes in IGF-I SDS were 3.63+/-1.67, 1.97+/-1.27, and -0.13+/-0.55 in high-dose (HD) group (0.012 mg/kg/day), low-dose (LD) group (0.006 mg/kg/day), and placebo group, respectively. Trunk fat mass decreased significantly (p<0.001) in HD group and LD group but not in placebo group (mean changes in percent trunk fat mass were -4.6+/-2.6%, -3.0+/-2.5% and 0.2+/-2.1% in HD group, LD group and placebo group, respectively). Serum LDL-cholesterol decreased in both GH treated groups but significantly only in HD group. Statistically significant dose-responsiveness was shown among three groups (p<0.001) with regards to IGF-I SDS, trunk fat mass, total fat mass, and lean body mass. The changes in serum IGF-I SDS, body composition, total cholesterol, and LDL-cholesterol at the end of double-blind study persisted throughout the open-label study. In addition, there was no clinically relevant adverse event during the both studies.

CONCLUSIONS

GH treatment significantly improved serum levels of IGF-I and body composition in a dose-responsive manner in Japanese AGHD patients. Total cholesterol and LDL-cholesterol levels also decreased. GH treatment was safe and generally well tolerated.

Growth hormone response to GH-releasing peptide-2 in children

The insulin tolerance test (ITT) has been considered the most reliable test in the diagnosis of growth hormone deficiency (GHD), but it is contraindicated in some patients. Recently, the use of GH-Releasing Peptide-2 (GHRP-2) has been validated and reported as a safe and reliable test for the diagnosis of adult severe GHD. We evaluated the GH response to GHRP-2 in 56 children with growth disorders to assess its efficacy. A dose of 2 microg/kg of GHRP-2 was administered intravenously and serum GH concentrations were determined. The Spearman correlation coefficient for GH peak values indicated a favorable correlation with the ITT (P<0.0001). Peak GH concentrations were significantly (p<0.0001) lower in children with (median: 3.39 microg/l (ng/ml)) than without (25.10 microg/l (ng/ml)) GHD. In the analysis of sensitivity-specificity curves, the serum concentration at the point where sensitivity crosses specificity was 15 microg/l (ng/ml). The GHRP-2 test was safe and required only one hour or less, and was capable of diagnosing GHD in children.

Measurement of human growth hormone by immunoassays: current status, unsolved problems and clinical consequences

Measuring the concentration of growth hormone (GH) in blood samples taken during dynamic tests represents the basis for diagnosis of growth hormone related disorders, namely growth hormone deficiency and growth hormone excess. Today, a wide spectrum of immunoassays are in use, enabling rapid and sensitive determination of growth hormone concentrations in routine diagnostics. From a clinical point of view several difficulties exist with the use and interpretation of GH assay results in the assessment of GH related disorders: Many physiological factors such as fat mass, age and gender influence the outcome of dynamic tests, overall leading to significant inter-individual differences in GH responses. However, in addition to the physiological variability, considerable variability exists in GH assay results obtained by different immunoassays. Unfortunately, all the new technical advances in the field of GH measurement techniques have not reduced this methodological variability. To a large extent, the actual values reported for the GH concentration in a sample depend on the method used by the respective laboratory. Obviously, such discrepancies limit the applicability of consensus guidelines on diagnosis and treatment in clinical practice. This review summarizes current practices for GH measurement with respect to the methods used, their limitations and the clinical consequences of the existing heterogeneity in GH immunoassay results.

Gender differences in serum GH and IGF-I levels and the GH response to dynamic tests in patients with acromegaly

Gender affects the GH secretory pattern both in normal subjects and in patients with acromegaly by an uncertain mechanism. Here, we report the influence of gender on the relationship between serum GH and IGF-I levels and the GH response to dynamic tests in patients with acromegaly. Seventy-four patients with untreated acromegaly (M/F 27/47, age range 22-86 yr.) were studied. The serum GH levels did not differ between male and female (6.1 vs. 8.7 ng/ml; p=0.26), while serum IGF-I levels, IGF-I SDS and the IGF-I/GH ratio were lower in female than those in male (679 vs. 769 ng/ml; p<0.02, 7.3 vs. 9.2 SDS; p<0.02 and 79.6 vs. 141.5; p<0.05). When the subjects were divided into two groups: age <or=50 yr, and age >50 yr, serum IGF-I levels and IGF-I/GH ratios were lower in female than those in male in patients <or=50 yrs (650 vs. 1002 ng/ml; p<0.05 and 59.8 vs. 142.9; p<0.05), but not in patients >50 yrs (684 vs. 680 ng/ml; p=0.39 and 98.7 vs. 118.4; p=0.40). The GH responses to OGTT, TRH, octreotide, and bromocriptine tests were similar in male and female. In conclusion, IGF-I/GH ratio was significantly lower in female than that in male particularly in younger patients with acromegaly. These data suggest that gender, presumably sex steroids in female, may partially modulate the relationship between circulating IGF-I and GH levels in patients with acromegaly.

Treatment of adult growth hormone deficiency: who, why and how? A review

Adult growth hormone deficiency (AGHD) is nowadays recognized as a distinct clinical entity and replacement therapy has become a standard practice. Reflecting on the accumulated evidence, questions nevertheless arise. Should all AGHD patients be treated? What dose of GH should be given and for how long? What are the real long-term benefits, in particular regarding life expectancy? if the diagnosis of severe GHD is firmly established and if there is no contra-indication (such as an active cancer or uncontrolled diabetes), it is worthwile initiating GH replacement therapy. Treatment can indeed correct the abnormal body composition, improve various adverse cardiovascular parameters and risk factors, increase muscle strength and bone mineral density and, although to a variable degree, improve the patient's quality of life and psychological well-being. Treatment should be started with very low doses to avoid side-effects related to fluid retention and should then be gradually titrated against IGF-I values, clinical response and individual tolerance.There is unfortunately no confirmed predictive factor for the overall therapeutic response in a given individual. Thus, the decision to whether or not pursue the therapy will depend on the ratio of perceived and expected benefits over cost and risks of treatment, as well as on the persistent motivation of the patient.

Alterations of carbohydrate and lipoprotein metabolism in childhood obesity--impact of insulin resistance and acanthosis nigricans

AIM

To study the prevalence of alterations of glucose and lipoprotein metabolism and the impact of acanthosis nigricans (AN) in childhood obesity.

PATIENTS AND METHODS

113 obese children, 57 with simple obesity (SO) and 58 with obesity and AN (OAN). Oral glucose tolerance test was performed, serum glucose, insulin and lipoprotein parameters were determined, and insulin resistance/sensitivity indices were calculated.

RESULTS

Insulin resistance, basal and reactive hyperinsulinemia, impaired glucose tolerance (IGT) and dyslipidemia were found to be frequent conditions in children with OS as well as OAN. Reactive insulinemia was more pronounced in OAN than in SO, and insulin resistance was more frequent when AN was more prominent. Triglycerides were higher and HDL-C was lower, and atherogenic dyslipidemia was more frequent in OAN compared to SO.

CONCLUSION

Children with obesity form a risk population. AN is a factor which can be used in metabolic risk factor clustering estimation in childhood obesity.

Detection of doping with recombinant human growth hormone

Detection of doping with recombinant human growth hormone is one of the challenges for antidoping analysis. This review focuses on the most important relevant publications that provide insight into the laboratory measurement of human growth hormone (hGH), antibodies and standards, the isoform approach and the biomarker approach. The isoform approach monitors the changes of hGH molecular isoform composition in serum and was applied at the Olympic Games in Athens in 2004, Turin in 2006 and Beijing in 2008. The markers approach detects a formula score, which reflects the changes in concentration of IGF-1 and P-III-P. All these methodologies measure the concentrations of growth hormone and its isoforms for isoform approach, or the concentrations of IGF-1 and P-III-P. All factors that affect these measurements should be taken into account for the development of methods to detect doping with recombinant hGH.

Problems with GH assays and strategies toward standardization

Disorders affecting GH secretion--either GH deficiency or GH excess (acromegaly)--are biochemically defined through peak or nadir concentrations of human GH in response to dynamic tests. Immunoassays employing polyclonal or monoclonal antibodies are routinely used for the analysis of GH concentrations, and many different assays are available on the market today. Unfortunately, the actual value reported for the GH concentration in a specific patient's sample to a large extent depends on the assay method used by the respective laboratory. Variability between assay results exceeds 200%, limiting the applicability of consensus guidelines in clinical practice. Reasons for the heterogeneity in GH assay results include the heterogeneity of the analyte itself, the availability of different preparations for calibration, and the interference from matrix components such as GH-binding protein. Furthermore, the reporting of results in mass units or international units together with the application of variable conversion factors led to confusion. International collaborations proposed measures to improve the comparability of assay results, recommending the use of a single, recombinant calibrator for all assays and reporting only in mass units as first steps. However, because of the differences in epitope specificity of antibodies used in different assays, method-specific cut-off levels for dynamic tests might remain necessary to correctly interpret and compare results from different laboratories.

The Leu544Ile polymorphism of the growth hormone receptor gene affects the serum cholesterol levels during GH treatment in children with GH deficiency

OBJECTIVE

The cellular effects of growth hormone (GH) are mediated by the interaction between GH and the GH receptor (GHR). We investigated the association between polymorphisms in GHR and changes in height standard deviation scores (SDS), and lipid metabolism during GH treatment for GH-deficient children.

DESIGN

A 1-year study on growth rate and lipid metabolism under GH treatment.

PATIENTS

Eighty-three children (61 boys and 22 girls) with GH deficiency were treated with GH for 1 year after diagnosis.

INTERVENTION

The patients were treated with recombinant human GH (0.19 mg/kg/week) for at least 1 year after diagnosis. The growth rates and biochemical parameters for lipid metabolism were measured both before and during treatment. Four single nucleotide polymorphisms (SNPs) in the GHR gene, Cys440Phe, Pro495Thr, Leu544Ile and Pro579Thr, and exon 3 deletion polymorphisms were genotyped by direct sequencing and multiplex PCR.

RESULTS

We found no significant association between GHR polymorphisms and changes in height SDS during GH treatment. The total cholesterol levels of the GH-deficient boys with Ile/Ile at codon 544 showed significantly higher cholesterol levels before GH treatment and then maintained high levels during the GH treatment, compared to those with other genotypes. No other polymorphisms seemed to have any apparent effects on lipid metabolism.

CONCLUSION

The Leu544Ile polymorphism of the GHR gene is associated with cholesterol levels in boys with GH deficiency.

What endocrinologists should know about growth hormone measurements

Determination of human growth hormone (GH) concentration in serum plays a key role in the diagnosis of GH deficiency and GH excess (acromegaly). Methods of measuring GH still lack standardization and show considerable between-method variability. Therefore, correct interpretation of GH test results requires knowledge of measurement techniques and awareness of potential problems in applying recommendations for cut-off values given in the literature. This article focuses on the molecular, structural, and methodologic background of the heterogeneity of assay results and on possible next steps toward standardization.

Growth hormone assays: current methodologies and their limitations

Measurement of circulating growth hormone (GH) concentrations is essential in diagnosis of either GH deficiency or GH excess. The invention of immunoassays for the measurement of peptide hormones was a major breakthrough, enabling the routine analysis of GH concentrations in larger series of samples. Over the last few decades, measurement technology has evolved from less sensitive, mainly radioactive assays based on polyclonal antisera to the latest generations of highly sensitive chemiluminescence methods employing monoclonal antibodies. Unfortunately, the development of newer assays did not lead to better agreement among the results obtained by different assay methods. On the contrary, the differences tended to increase when monoclonal antibody based assays became more popular. The actual value reported for the GH concentration in a specific patient's sample still mainly depends on the method used by the respective laboratory, limiting the applicability of international consensus guidelines in clinical practice. The heterogeneity of the analyte itself, the availability of different reference preparations for calibration and the interference from matrix components such as GH binding protein are among the reasons why standardizing GH assays is difficult. An additional challenge arose from the availability of a GH receptor antagonist for the treatment of acromegaly, which is basically a mutated form of GH and therefore interferes in many GH assays. This review provides an overview on GH assays used in clinical practice, their limitations and the potential next steps towards standardization.

Standardization of blood growth hormone levels measured by different kits using a linear structural relationship

Accurate and reliable determination of blood growth hormone level is essential in the diagnosis and treatment of short stature children. However, measured levels differed considerably among measurement kits available in Japan until 2003. Therefore, standardization of the measured values was attempted by measuring growth hormone levels in a sample of healthy adult individuals every year using the different kits. A standardization equation was developed for each kit through linear structural relationship with the mean values of the used kits and measured values in each kit as random variables. A Pearson's correlation coefficient between the mean values of all kits and the measured values from each kit was also obtained. Sources for the marked discrepancies amongst the measured values in the different kits were also explored. The obtained values for slopes and intercepts in the equations varied considerably, but the standard values obtained from these equations after the measured values for each kit were transformed into standard values served well as the standard. The standard solutions in the respective measurement kits were found to be the source of variability in the measured values among the kits.