MKRN3 circulating levels in girls with central precocious puberty caused by MKRN3 gene mutations

PURPOSE

MKNR3 is a paternally expressed gene whose mutations are the main cause of central precocious puberty (CPP). Protein circulating levels can be easily measured, as demonstrated in idiopathic CPP and healthy controls. No data are available for patients harboring an MKRN3 mutation. Our aim was to perform MKRN3 mutation screening and to investigate if circulating protein levels could be a screening tool to identify MKRN3 mutation in CPP patients.

METHODS

We enrolled 140 CPP girls and performed MKRN3 mutation analysis. Patients were stratified into two groups: idiopathic CPP (iCPP) and MKRN3 mutation-related CPP (MKRN3-CPP). Clinical characteristics were collected. Serum MKRN3 values were measured by a commercially available ELISA assay kit in MKRN3-CPP and a subgroup of 15 iCPP patients.

RESULTS

We identified 5 patients with MKRN3 mutations: one was a novel mutation (p.Gln352Arg) while the others were previously reported (p.Arg328Cys, p.Arg345Cys, p.Pro160Cysfs*14, p.Cys410Ter). There was a significant difference in circulating MKRN3 values in MKRN3-CPP compared to iCPP (p < 0.001). In MKRN3-CPP, the subject harboring Pro160Cysfs*14 presented undetectable levels. Subjects carrying the missense mutations p.Arg328Cys and p.Gln352Arg showed divergent circulating protein levels, respectively 40.56 pg/mL and undetectable. The patient with the non-sense mutation reported low but measurable MKRN3 levels (12.72 pg/mL).

CONCLUSIONS

MKRN3 defect in patients with CPP cannot be predicted by MKRN3 circulating levels, although those patients presented lower protein levels than iCPP. Due to the great inter-individual variability of the assay and the lack of reference values, no precise cut-off can be identified to suspect MKRN3 defect.

Prospective urinary albumin/creatinine ratio for diagnosis, staging, and organ response assessment in renal AL amyloidosis: results from a large cohort of patients

OBJECTIVES

Quantification of 24 h-proteinuria is the gold standard for diagnosing, staging, and monitoring of patients with renal AL amyloidosis. However, 24 h-urine collection is cumbersome and may result in preanalytical error. In this prospective study, we investigated the role of urinary albumin/creatinine ratio (UACR) (cut-off: 300 mg/g) identifying renal involvement, evaluated a UACR-based staging system (UACR cut-off: 3,600 mg/g) and assessed whether UACR response (UACR decrease >30% without worsening in eGFR >25%) predicts renal outcome in 531 patients with newly-diagnosed AL amyloidosis.

METHODS

From October 2013 paired 24 h-proteinuria and UACR (on first morning void) were measured in all newly-diagnosed patients with AL amyloidosis. Correlation between 24 h-proteinuria and UACR at baseline was assessed by Pearson's r test. Impact of UACR response on renal outcome was assessed in randomly created testing (n=354) and validation (n=177) cohorts.

RESULTS

A strong linear correlation was found between 24 h-proteinuria and UACR at baseline (r=0.90; p<0.001). After a median follow-up of 31 months, 57 (11%) patients required dialysis. A UACR-based renal staging system identified three stages with significantly higher dialysis rate at 36 months comparing stage I with stage II and stage II with stage III. Achieving a renal response, according to a UACR-based criterion, resulted in lower dialysis rate in both testing and validation cohorts.

CONCLUSIONS

UACR is a reliable marker for diagnosis, prognosis, and organ response assessment in renal AL amyloidosis and can reliably replace 24 h-proteinuria in clinical trials and individual patients' management.

Minimal residual disease negativity by next-generation flow cytometry is associated with improved organ response in AL amyloidosis

Light chain (AL) amyloidosis is caused by a small B-cell clone producing light chains that form amyloid deposits and cause organ dysfunction. Chemotherapy aims at suppressing the production of the toxic light chain (LC) and restore organ function. However, even complete hematologic response (CR), defined as negative serum and urine immunofixation and normalized free LC ratio, does not always translate into organ response. Next-generation flow (NGF) cytometry is used to detect minimal residual disease (MRD) in multiple myeloma. We evaluated MRD by NGF in 92 AL amyloidosis patients in CR. Fifty-four percent had persistent MRD (median 0.03% abnormal plasma cells). There were no differences in baseline clinical variables in patients with or without detectable MRD. Undetectable MRD was associated with higher rates of renal (90% vs 62%, p = 0.006) and cardiac response (95% vs 75%, p = 0.023). Hematologic progression was more frequent in MRD positive (0 vs 25% at 1 year, p = 0.001). Altogether, NGF can detect MRD in approximately half the AL amyloidosis patients in CR, and persistent MRD can explain persistent organ dysfunction. Thus, this study supports testing MRD in CR patients, especially if not accompanied by organ response. In case MRD persists, further treatment could be considered, carefully balancing residual organ damage, patient frailty, and possible toxicity.

Proteotoxicity in cardiac amyloidosis: amyloidogenic light chains affect the levels of intracellular proteins in human heart cells

AL amyloidosis is characterized by widespread deposition of immunoglobulin light chains (LCs) as amyloid fibrils. Cardiac involvement is frequent and leads to life-threatening cardiomyopathy. Besides the tissue alteration caused by fibrils, clinical and experimental evidence indicates that cardiac damage is also caused by proteotoxicity of prefibrillar amyloidogenic species. As in other amyloidoses, the damage mechanisms at cellular level are complex and largely undefined. We have characterized the molecular changes in primary human cardiac fibroblasts (hCFs) exposed in vitro to soluble amyloidogenic cardiotoxic LCs from AL cardiomyopathy patients. To evaluate proteome alterations caused by a representative cardiotropic LC, we combined gel-based with label-free shotgun analysis and performed bioinformatics and data validation studies. To assess the generalizability of our results we explored the effects of multiple LCs on hCF viability and on levels of a subset of cellular proteins. Our results indicate that exposure of hCFs to cardiotropic LCs translates into proteome remodeling, associated with apoptosis activation and oxidative stress. The proteome alterations affect proteins involved in cytoskeletal organization, protein synthesis and quality control, mitochondrial activity and metabolism, signal transduction and molecular trafficking. These results support and expand the concept that soluble amyloidogenic cardiotropic LCs exert toxic effects on cardiac cells.

A 5.8 Mb interstitial deletion on chromosome Xq21.1 in a boy with intellectual disability, cleft palate, hearing impairment and combined growth hormone deficiency

Background

Deletions of the long arm of chromosome X in males are a rare cause of X-linked intellectual disability. Here we describe a patient with an interstitial deletion of the Xq21.1 chromosome.

Case presentation

In a 15 year boy, showing intellectual disability, short stature, hearing loss and dysmorphic facial features, a deletion at Xq21.1 was identified by array-CGH. This maternally inherited 5.8 Mb rearrangement encompasses 14 genes, including BRWD3 (involved in X-linked intellectual disability), TBX22 (a gene whose alterations have been related to the presence of cleft palate), POU3F4 (mutated in X-linked deafness) and ITM2A (a gene involved in cartilage development).

Conclusion

Correlation between the clinical findings and the function of gene mapping within the deleted region confirms the causative role of this microrearrangement in our patient and provides new insight into a gene possibly involved in short stature.

Growth hormone receptor gene expression in puberty

The mechanisms regulating the synergic effect of growth hormone and other hormones during pubertal spurt are not completely clarified. We enrolled 64 females of Caucasian origin and normal height including 22 prepubertal girls, 26 pubertal girls, and 16 adults to evaluate the role of Growth Hormone/Insulin-like growth factor-I axis (GH/IGF-I) during the pubertal period. In these subjects both serum IGF-I and growth hormone binding protein levels, as well as quantitative growth hormone receptor (GHR) gene expression were evaluated in peripheral lymphocytes of all individuals by real-time PCR. Our results showed significantly lower IGF-I levels in women (148±10 ng/ml) and prepubertal girls (166.34±18.85 ng/ml) compared to pubertal girls (441.95±29.42 ng/ml; p<0.0001). Serum GHBP levels were significantly higher in prepubertal (127.02±20.76 ng/ml) compared to pubertal girls (16.63±2.97 ng/ml; p=0.0001) and adult women (19.95±6.65 ng/ml; p=0.0003). We also found higher GHR gene expression levels in pubertal girls [174.73±80.22 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase)] compared with other groups of subjects [women: 42.52±7.66 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase); prepubertal girls: 58.45±0.18.12 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase)], but the difference did not reach statistical significance. These results suggest that sexual hormones could positively influence GHR action, during the pubertal period, in a dual mode, that is, increasing GHR mRNA production and reducing GHR cleavage leading to GHBP variations.

Adherence to growth hormone therapy: a practical approach

BACKGROUND

Early detection of suspected poor adherence to growth hormone (GH) therapy is crucial to achieve normal final height in GH-deficient (GHD) patients.

PATIENTS

106 children (73 M, 33 F) with a median age of 10.47±3.48 years (mean±standard deviation score (SDS)) exhibited short stature (-1.76±0.64 SDS) and a delayed bone age (8.68±3.42 years). Severe GHD was found in 28, while partial GHD was seen in 78 cases, with low IGF-I values. Recombinant human GH was administered by daily subcutaneous injection at a dosage of 21 µg/kg in prepubertal and 25 µg/kg in pubertal patients.

RESULTS

Poor adherence was suspected in a number of patients, but clearly demonstrated in only 4 cases with persistent reduced height velocity in spite of a corrected therapeutic regimen. These patients admitted incomplete adherence to GH injections and clinical and anthropometric measurements revealed their poor response to therapy.

CONCLUSIONS

To efficaciously improve adherence in GHD patients, it is mandatory to regularly interview patients; a non-aggressive approach might be utilized to ensure effective communication with patients and their parents.

Metabolic parameters and adipokine profile in growth hormone deficient (GHD) children before and after 12-month GH treatment

It is a common knowledge that GH exhibits a large number of metabolic effects, involving lipid and glucose homeostasis. The aim of the study was to investigate the effect of one year GH therapy on metabolic parameters and adipokines in GH deficient (GHD) children. Sixteen prepubertal children (11 M and 5 F) with complete GHD (age range: 3.4-14.7 years) and 20 (13 M and 7 F) age and sex-matched healthy children (age range: 4.6-12.3 years) were studied. Blood was collected from patients before starting GH therapy (0.025 mg/kg/day) and one year later, and from healthy children to measure adiponectin, leptin, osteoprotegerin, resistin, interleukin (IL)-6, tumor necrosis factor (TNF)-α levels, and other glucose and lipid metabolism parameters. Adiponectin and resistin levels were significantly higher (49980 ng/ml vs. 14790 ng/ml and 11.0 pg/ml vs. 6.3, respectively) in GHD children before GH therapy than in controls. Serum IGF-I levels (p=0.0001) and height SDS (p<0.0001) significantly increased after 12 months' of GH therapy. There was a loss of body fat reflected by a significant decline in tricep (p=0.0003) and subscapular skinfold thickness SDS (p=0.0023). After 12 months, there was a significant rise in insulin (p=0.0052) and leptin levels (p=0.0048) and a significant decrease in resistin (p=0.0312) and TNF-α (p=0.0137). We observed that lipid and glucose metabolisms are only slightly affected in GHD children. Growth hormone replacement therapy affects some factors, such as leptin, resistin and fat mass, suggesting that also in children, GH treatment has a role in the regulation of factors secreted by adipose tissue.

Growth hormone variants: a potential avenue for a better diagnostic characterization of growth hormone deficiency in children

Human GH (hGH) is a heterogeneous protein hormone consisting of several isoforms. This heterogeneity is the consequence of multiple hGH genes, mRNA splicing, post-translational modifications, and peripheral metabolism, and it represents one important reason for the disparity among GH assay results from different laboratories. However, other factors are involved: a) interference from endogenous GH binding proteins; b) different specificities of anti- GH (monoclonal and polyclonal) antibodies; c) different matrix effects among the calibrators; d) the use of different calibrators. The measurement of GH levels in response to provocative testing is an essential part of the diagnosis of GH deficiency. For this purpose, an accurate, reproducible and universally valid GH measurement would be highly desirable, but, despite a huge number of efforts in clinical biochemistry, this goal remains elusive.

Diagnosis of growth hormone deficiency is affected by calibrators used in GH immunoassays

Growth hormone (GH) values vary among immunoassays depending on different factors, such as the assay method used, specificity of antibodies, matrix difference between standards and samples, and interference with endogenous GH binding proteins (GHBPs). We evaluated whether the use of different calibrators for GH measurement may affect GH values and, consequently, the formulation of GH deficiency (GHD) diagnosis in children. Twenty-three short children (5 F, 18 M; age 11.4±3.1 years), with the clinical characteristics of GHD (height:  -2.3±0.5 SDS; height velocity  -2.3±1.5 SDS; IGF-I  -1.2±0.9 SDS), underwent GH stimulation tests to confirm the clinical diagnosis of GHD. Serum GH values were measured with Immulite 2000, using 2 different calibrators, IS 98/574, a recombinant 22 kDa molecule of more than 95% purity, and IS 80/505, of pituitary origin and resembling a variety of GH isoforms. We found blunted GH secretion in 20 subjects with the Immulite assay using the IS 98/574 GH as a calibrator, confirming the diagnosis of GHD. Subsequently, using IS 80/505 GH as a calibrator, in the same samples only 14 children showed reduced GH levels. The total cost for the first year of GH therapy of patients diagnosed with IS 98/574 as a calibrator was higher than that for patients diagnosed with IS 80/505 as a calibrator. These data confirm that GH values may depend on different calibrators used in the GH assay, affecting the formulation of GHD diagnosis and the consequent decision to start GH treatment.

Childhood obesity: know it to prevent it

Obesity can be defined as an excess of adipose tissue. It is associated to a significantly increased risk of cardiovascular disease, hypertension, diabetes mellitus and hypercholesterolemia. The results of the Italian survey called Okkio alla Salute (2010), which was attended over 42'000 students of third-class of primary school and 44'000 parents, confirm bad eating habits, sedentary lifestyles and excess weight. In particular, 22,9% of the children resulted overweight and 11,1% obese. The prevalence of obesity is higher in the south of Italy than in the north and in males rather than in females. Moreover, parents do not always have a real idea of the physical aspect of their son: 36% of the mothers of overweight or obese children are do not believe their child is overweight. Just 29% of them think that the quantity of food eaten by their child is excessive. The relative risk for an obese child to become an obese adult increases with the age and is directly correlated to the severity of overweight. Among obese children of preschool age, 26 to 41% will be an obese adult., Among scholar children, the percentage increases to 69%. The paper describes a multidisciplinary approach the disease, in fact, dietary and behavioural modifications, associated with physical activity, have the purpose of educate overweight and of preventing the onset of complications or reducing their severity if already present and reversible.

Efficacy of long-term growth hormone therapy in short children with reduced growth hormone biological activity

AIM

The optimal GH regimen, in terms of cost-effectiveness, in children with normal GH immunoreactivity but reduced bioactivity is still debated.

METHODS

In 12 GH-deficient (GHD) and 12 bioinactive GH children undergoing GH treatment we evaluated the increase in growth velocity, the difference between target height and final stature and the incremental cost-effectiveness ratio.

RESULTS

We found a significant (p < 0.05) increase in growth velocity in both groups during the first year of GH treatment (non- GHD: from -1.7 to 5.4 SDS; GHD: from -1.46 to 4.74 SDS). There was no statistically significant variation between the two groups in the difference between final height and target height. We did not find any significant difference in cost/height gain between GHD (1925.28 ± 653.15 euro) and bioinactive GH children (1639.55 ± 631.44 euro). There were also no significant differences in cost/year of therapy between GHD (12347.68 ± 2018.1 euro) and bioinactive GH children (11355.08 ± 1747.61 euro).

CONCLUSION

In children with reduced GH biological activity, confirmed by the increase of serum IGF-I levels during generation test, the cost of GH treatment is justified by the positive results obtained in growth and adult height as in classical GHD patients.

Serum IGF-I and IGFBP-3 reference values from a chemiluminescent assay in normal children and adolescents of hispanic and italian origin: presence of sexual dimorphism in IGF-I values

Serum IGF-I and IGFBP-3 assays are used to monitor rhGH treatment. Some discrepancies in results obtained by means of different assays have been reported. The aim of this study was to establish normal ranges for circulating IGF-I and IGFBP-3 in children and adolescents of Hispanic and Italian origin. Circulating levels of IGF-I and IGFBP-3 were measured in 169 Hispanic and Italian prepubertal children and 66 adolescents of both sexes, using a chemiluminescent assay. Serum levels of IGF-I and IGFBP-3 increased from early childhood into adolescence. After pubertal peaks of IGF-I and IGFBP-3, slight decreases were observed with increasing age. Furthermore, serum IGF-I levels were significantly higher in girls than in boys, suggesting a sexual dimorphism in serum IGF-I values in late prepuberty and early puberty. Differences in IGF-I and IGFBP-3 absolute values between our study and previous studies suggest the need to establish reference ranges for each ethnic group.

Hyperimmunoglobulinaemia in Babinga Pygmies is Present from Infancy

Pygmies, a population characterized by short stature, have high immunoglobulin (Ig) concentrations. In this study, we evaluated Ig levels in Cameroon's Babinga Pygmies from infancy to adulthood and the effects of a national health program on these Ig levels. We found that IgG and IgM levels were outside the normal range for Italians of the same age and were comparable to those measured in Babinga Pygmies living in the same region by Siccardi in 1975. In conclusion, the hypergammaglobulinaemia of Babinga Pygmies is already present in infants and is not affected by sanitation improvements, suggesting that it could be partly genetically-determined.

Growth hormone isoforms release in response to physiological and pharmacological stimuli

Ten healthy subjects used to performing regular physical activity and eight subjects affected by idiopathic isolated GH deficiency (GHD) were enrolled; 22- and 20-kDa GH secretion and its biological activity were evaluated in response to pharmacological stimuli such as arginine, L-dopa or glucagon in GHD children, while the hormonal response to exercise was studied according to Bruce protocol in healthy subjects. We found a significant increase in 22- and 20-kDa GH level in healthy subjects after monitored physical exercise (MPE; basal 0.28+/-0.12 vs 7.37+/-2.08 ng/ml and basal 0.076+/-0.04 vs 0.18+/-0.05 ng/ml, respectively). Furthermore, the 22-kDa/20-kDa ratio significantly increased in children who had undergone MPE and the GH bioactivity basal mean value also increased significantly after exercise (basal 2.86+/-0.76 vs 7.64+/-1.9 ng/ml). The mean value of 22-kDa GH in GHD patients increased significantly following GH pharmacological stimulation (2.78+/-0.63 ng/ml) when compared with mean basal (0.20+/-0.11 ng/ml) value. In the GHD group the basal concentration of 20-kDa GH significantly increased following GH pharmacological stimulation (0.34+/-0.11 vs 0.72+/-0.2 ng/ml); the 22-kDa/20-kDa ratio significantly increased too. Likewise, GH bioactivity in children with GHD increased significantly after pharmacological stimulation test (basal 2.53+/-0.56 vs 7.33+/-1.26 ng/ml). Both GH isoform concentrations and their biological activity are significantly increased in healthy subjects after submaximal exercise protocol and in GHD children after pharmacological stimuli.

[Fluticasone in the therapy of asthmatic children: short-term effects on growth]

AIM

Inhaled corticosteroids (ICS), for years used in the therapy of low-moderate bronchial asthma, reduce the rate of asthmatic attack with improved pulmonary functioning and quality of life. Clinical trials have been addressed mainly to study the efficacy rather than the safety of drugs, so that the side effects of these drugs have not yet been accurately defined. Clinical experience shows that growth delay appears in the first months of therapy with ICS. The aim of the study was to evaluate the influence of the therapy with spacer-administered inhaled corticosteroid on short-term auxological development in prepubertal children.

METHODS

In a group of children with low asthma, height and weight have been evaluated before and after six months of inhaled therapy with dipropionate fluticasone at a dose of 100 microg per day.

RESULTS

Twenty-five patients (19 males and 6 females; age 5.5+/-1.6 years; range: 2.6-7.8 years) showed a regular growth during the six months of therapy (mean height 0.8 standard deviation score [SDS] before therapy and 0.8 SDS after therapy), while 21 (17 males and 4 females; age 10.0+/-1.5 years; range 8.0-12.7 years) showed an increment of growth rate (mean height from 0.5 SDS to 0.7 SDS, respectively).

CONCLUSION

Spacer-administered low dose fluticasone does not negatively influence short-term growth rate, regardless of the age of the patients.

Unreliability of classic provocative tests for the diagnosis of growth hormone deficiency

In this study we investigated 9 prepubertal children with blunted GH response to classic pharmacological stimuli in contrast with normal auxological evaluation. The children were followed to evaluate their growth velocity for a longer period before starting replacement GH therapy. To evaluate the pituitary reserve a supraphysiologic stimulus such as GHRH plus arginine was used. Serum GH levels were measured by a time-resolved immunofluorimetric assay before and after 1 microg/kg body weight iv injection of GHRH, while serum PRL, IGF-I, and insulin were evaluated only in basal conditions using an automatic immunometric assay. Out of 9 studied subjects, 7 underwent GHRH plus arginine administration and showed a normal GH response; the parents of the remaining 2 children refused the test. Normal serum levels of PRL, IGF-I, insulin, and a normal insulin sensitivity were observed in all children. After 1 yr, the growth rate in each patient was further improved and reached almost normal values. Our results further confirm that the decision to start replacement GH therapy should be based on both auxological parameters and laboratory findings. The GHRH plus arginine test appears to be useful to identify false GH deficiency in children showing a blunted GH response to classic stimuli in contrast with normal growth rate.

[Changes in circulating levels of adiponectin and leptin in children during the first two years of life]

AIM

Adiponectin, leptin and insulin play an important role in the control of growth and glyco-metabolic homeostasis both during pre- and post-natal life. In order to find out markers indicative of post-natal growth, we evaluated circulating levels of these growth factors in full term small for gestational age (SGA) children, during the first 2 years of life, correlating them with the auxological parameters.

METHODS

Fourteen SGA (8 males and 6 females) and 16 AGA (appropriate for gestional age) infants (7 males and 9 females) have been included in this study, recording length, weight, body mass index (BMI), adiponectin, leptin and insulin levels at birth. In SGA subjects, these biochemical and clinical parameters have also been evaluated at the first and at the second year of age.

RESULTS

AGA and SGA adiponectin and insulin levels at birth did not show statistically significant differences, while leptin concentrations were significantly (P=0.011) lower in SGA children (median 418.49, range 157.68-903.67 pg/mL) in comparison with AGA ones (median 811.71, range 312.50-3085.95 pg/mL).

CONCLUSIONS

In conclusion, at birth adiponectin and insulin levels do not differ between AGA and SGA subjects while leptin concentrations are significantly lower in SGA infants and positively correlated to the birthweight.

[Spinocerebellar ataxias in infancy: pathogenesis of potassium and calcium channels' diseases, clinical features and therapeutical approach]

In infancy, the autosomal dominant inherited ataxias are severe neurological diseases, due to inherited mutations of ion channels. The main forms are: episodic ataxia type 1 (EA1), episodic ataxia type 2 (EA2), spinocerebellar ataxia type 6 (SCA6). EA1 is due to a mutation in KCNA1, the gene encoding human Kv1.1 on chromosome 12p13, which contributes as a subunit to the formation of potassium channels in motor nerve terminals and in many central nervous system neurones. To date, there are fifteen different mutations, which affect potassium channel's properties and lead to phenotypic variability and to different responses to therapy. EA2 can result from mutations in the CACNA1A gene, encoding calcium channels on chromosome 19p13.1 and widely distributed throughout the central nervous system. To date, associated with EA2, in the CACNA1A gene thirty different mutations have been described, resulting in altered or truncated protein products and, as a consequence, in nonfunctional calcium channels. There is phenotypic variability, also inside the same family, without correlation genotype-phenotype. SCA6 is a progressive neurodegenerative disease due to mutations of the CACNA1A gene. CACNA1A is responsible for both EA2 and SCA6. Nevertheless, the pathogenesis of the two diseases is different: SCA6 is associated with small expansion of a CAGn repeat, while EA2 is due to point mutations. Clinically, SCA6 is characterized by a slowly progressive development and by an inverse correlation between the number of repeats and the severity of the disease.

Variations in Biological and Immunological Activity of Growth Hormone during the Neonatal Period

BACKGROUND/AIMS

It was postulated that a high growth hormone (GH) bioactivity might explain the rapid growth rate of neonates. The aim of this study is to verify changes in serum GH biological potency (Bio-/Immuno-GH ratio) and their effects on serum growth factors during the first month of life in term and preterm babies.

METHODS

Blood samples were collected from 10 small-for-gestational-age preterm (SGAPT), 17 appropriate for gestational age preterm (AGAPT) and 26 AGA term (T) neonates on days 4, 15 and 30 of life to evaluate serum GH values measured by IFMA (IFMA-GH) and bioassay (Bio-GH), serum insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3).

RESULTS

High serum Bio-GH values on the first few days of life correspond to high IFMA-GH values, suggesting full biological potency of circulating GH. Furthermore, IGF-I/IGFBP-3 molar ratio values in preterm babies were higher than in full-term infants.

CONCLUSIONS

These data confirmed the hypothesis that the higher growth velocity in the first month of life of preterm neonates is due to an increased bioavailability of IGF-I. A progressive maturation of the hypothalamic-pituitary-IGF-I axis without any alteration in the GH biological potency seems to underpin the increase of the growth factors early in life.

Geometry and bone density

Bone development is a key process in the growing child. It is, therefore, of paramount importance to survey this process, which is characterized by increasing length and size of the bone together with its progressive mineralization. The bone status can be evaluated by different techniques, each of them having its pros and cons. Furthermore, it should be underlined that the results of bone assessment depend not only from the employed technique but also from the auxological characteristics of the subjects. It is, therefore, the aim of this review to examine the characteristics of the various methods of bone evaluation, such as dual energy X-ray absorptiometry (DEXA), peripheral quantitative computed tomography (pQCT), ultrasound and metacarpal index and to explain how changes in bone structure and geometry may influence the results.

Differences in serum GH cut-off values for pharmacological tests of GH secretion depend on the serum GH method. Clinical validation from the growth velocity score during the first year of treatment

BACKGROUND

The serum GH cut-off value for pharmacological tests of GH secretion (PhT GH) depends on the type of test and also on the method used for determining serum GH. Cut-off serum GH values as different as 5-10 ng/ml, have been reported, and have been validated biochemically. We have used the growth velocity (GV)-standard deviation score (SDS) during the first year of treatment with rhGH to validate these cut-offs on a biological basis.

METHODS

Fifty pre-pubertal patients with short stature (height < or =-2 SDS and GV < or =-1.2 SDS) were studied. GH deficiency (GHD) was diagnosed in 39 patients, on the basis of clinical and auxological parameters and on the serum concentration of IGF-1, and non-GHD in the other 11 patients. Two PhT GH (arginine and clonidine) were carried out in the 50 patients. Serum GH was determined by two different methods: one detecting most of serum GH isoforms, named Total GH (HGH Bio-Tech, MAIA Clone), and another one, only detecting the 22 kDa GH, named 22K GH (GH-22K IFMA, Wallac).

RESULTS

Basal data: all patients with GHD and with non-GHD had maximal serum GH response (MaxR) values below and above the cut-off, respectively, for the serum Total GH and 22K GH. The mean 22K GH/Total GH ratio was similar to previous publications. Post-rhGH treatment data: the two groups improved their height SDS during the first year of treatment, particularly patients with GHD. A receiver-operator curve was used to define the best threshold for post-treatment GV-SDS that separates GHD from non-GHD patients. This value was 1.91 GV-SDS. A negative correlation between first year treatment GV-SDS and pre-treatment serum GH MaxR was found for the two assays (p < 0.001). Then, the best cut-off GV-SDS, previously calculated with the receiver-operator curve (1.91 SDS) was used to interpolate the corresponding serum GH values, as determined by the two methods. For Total GH, the value was 10.8 ng/ml, and for 22K GH, it was 5.4 ng/ml.

CONCLUSION

The cut-off values calculated by biological means to separate GHD from non-GHD were remarkably similar to those calculated biochemically (10.0 and 4.8 ng/ml, respectively) for Total and 22K GH. This is a biological validation for using different cut-off values, appropriate for each assay, to diagnose GHD.

Dose dependency of the serum bio/immuno GH ratio in children during pharmacological secretion tests

Dissociation between GH bioactivity (bio-GH) and GH immunoactivity (immuno-GH) is due to the heterogeneity of the molecule: the measurements do not always provide reliable information on the bio-GH. We studied the ratio of bio-GH and immuno-GH during pharmacological secretion tests in 211 sera to study the concentration-response curve of the assay (C1), 16 samples of normally growing subjects with idiopathic short stature (C2), 13 samples from patients with GH deficiency (GHD1) and 6 samples of 3 patients with GHD and normal provocative tests (GHD2). GH bioactivity was determined by the Nb2 cell proliferation assay (bio-GH) and immuno-GH by a time-resolved immunofluorometric assay (IFMA) (immuno-GH). A non-linear negative relationship between the serum bio-GH/immuno-GH ratio and serum immuno-GH was observed in C1. In log-log plotting representation, two cut-off lines were drawn: a vertical cut-off line separating above-below cut-off serum peak immuno-GH values in provocative tests, and a diagonal cut-off line separating normal-abnormal serum bio-GH/immunoGH ratio; four areas were defined. GHD1 had normal ratios, but below cut-off peak immuno-GH responses. P2 and P3 of Group GHD2 had abnormal ratios in samples with low serum immuno-GH but only P2 had autosomal dominant mutation. P1 had the same autosomal dominant isolated GHD as P2 but a low normal ratio. Our data underline the importance of relatively low serum GH concentrations in mediating GH biological actions. An abnormal serum bio-GH/immuno-GH ratio might explain certain cases of GHD and might be useful in detecting abnormal circulating isoforms of GH in patients with growth failure.

The risk of diabetes mellitus in children born small for gestational age and treated with recombinant growth hormone

Children born small for gestational age (SGA) are known to be at risk for both short stature and type 2 diabetes mellitus in later life. To evaluate the influence of recombinant growth hormone (rhGH) therapy on insulin sensitivity, 24 children born SGA were treated with GH at traditional doses, from 0.23 mg/kg/week (group A) to 0.46 mg/kg/week (group B). We evaluated glycosylated haemoglobin, basal glucose and insulin levels before and 1 and 2 years after GH therapy. The homeostasis model assessment (HOMA) index was used to evaluate insulin sensitivity. After 2 years of GH therapy, glycosylated haemoglobin and basal glucose did not change significantly. Insulin sensitivity fell, but still remained within the normal range. In conclusion, 2-year GH therapy had beneficial effects in SGA children without changes in glucose homeostasis. Moreover, the insulin sensitivity reduction did not correlate to the GH dose used.

Can GH induce chromosome breaks or microsatellite instability in GH-deficient children?

The role of GH in carcinogenesis is unclear. We studied the effect of recombinant human GH (rhGH) in vitro on chromosomal and genomic instability. Thirteen children, aged 9.57 +/- 1.08 yr (mean +/- SEM), with complete (no.=5) or partial (no.=8) GH deficiency were evaluated before and during GH treatment. We examined the incidence of chromosome and chromatid breaks, and microsatellite instability after in vitro addition of two different doses of rhGH to peripheral blood lymphocytes obtained from the patients. No differences were observed between the samples of GH-deficient children before and after GH therapy as regards the percentage of chromosome and chromatids breaks, and in microsatellite instability. Our data show that in vitro addition of rhGH does not induce chromosomal and/or genomic instability in cultured lymphocytes.

Hyperparathyroidism

Hyperparathyroidism is a disease characterized by hypercalcemia with hypophosphoremia resulting from increased secretion of parathyroid hormone (PTH). The disease may be divided into 3 forms: a) primary, b) secondary, c) tertiary (secondary refractory form). Primary hyperparathyroidism is rare in children; hyperplasia is more frequent during the early years of life (neonates and infants) and is difficult to distinguish from adenoma in children. The disease may be asymptomatic; elevated calcemia levels (>12 <13.5 mg/dl) are accompanied by anorexia, asthenia and persistent stipsis; severely elevated concentrations (>13.5 mg/dl) are accompanied by nausea, vomiting, polyuria due to osmosis, with dehydration and progressive onset of lethargy, stupor and coma. Osteopenia or osteitis fibrosa cystica may be present due to augmented bone resorption. Height and weight increases are altered due to anorexia and dehydration. Differential diagnosis includes iatrogenic causes of hypercalcemia (excessive vitamin D intake, prolonged immobilization, etc.) and idiopathic familial hypercalcemia. Emergency treatment is required in cases of extremely elevated hypercalcemia (Ca >13.5-14 mg/dl), due to risk of injury to the heart, the central nervous system, the gastrointestinal tract and the kidneys. The 4 cardinal points of treatment are: hydration, calciuresis, inhibition of bone calcium resorption, treatment of the cause underlying hyperparathyroidism. Secondary hyperparathyroidism is found in cases where chronic hypocalcemia is present, particularly in chronic renal failure, untreated deficiency rickets, chronic intestinal malabsorption, hepatobiliary disease, types I and II vitamin D-dependent rickets, tubular acidosis or Fanconi's syndrome. The tertiary form is distinguished by the autonomous nature of the parathyroid glands which have become hypertrophic/hyperplastic due to uncontrollable, chronic severe renal failure. It can also be of iatrogenic origin due to excessive intake of inorganic phosphates in familial hypophosphatemic rickets or chronic vitamin D deficiency.

Growth Hormone (GH) Isoforms Following Acute 22-kDa GH Injection: Is it Useful to Detect GH Abuse?

The aim of the study was to investigate the influence of an acute administration of 22-kDa hGH (22-kDa GH) on 22-kDa GH and 20-kDa GH serum levels, biological activity of GH (Nb2-GH) and on 22-kDa/20-kDa GH ratio, in order to verify whether the assessment of the GH isoforms could be a potential tool for diagnosing GH abuse. Twenty-eight children (21 M, 7 F), age 10.4 +/- 0.8 y, affected by idiopathic isolated GH deficiency and 10 children (8 M, 2 F), age 9.2 +/- 2.3 y affected by constitutional growth delay, were evaluated. After an overnight fast, a basal blood sample was obtained between 8 a.m. and 9 a.m. and a dose of 22-kDa GH was then administered subcutaneously (0.1 U/Kg). Blood was drawn after 2, 4 and 6 h, for the evaluation of 22-kDa GH, Nb2-GH and 20-kDa GH serum levels. Similar results were obtained in patients and controls: a significant rise, although of variable amplitude, of 22-kDa GH and Nb2-GH was found (p < 0.001) and the maximum peak was detected after 4 h in the majority of subjects. No acute changes in 20-kDa GH serum levels were observed. The 22-kDa/20-kDa GH ratio increased progressively, due to the rising levels of 22-kDa GH. A positive correlation was seen between 22-kDa GH and Nb2-GH levels at baseline and at 2, 4 and 6 h (p < 0.014, r = 0.99). Since in normal subjects the ratio of endogenous 22-kDa GH and 20-kDa GH is constant, an altered ratio of 22-kDa/20-kDa GH is highly suggestive of GH abuse. The short period of time available for the evaluation however (within 3 h from GH injection), severely limits this investigational tool in athletes.

Increased insulin-like growth factor (IGF)-II and IGF/IGF-binding protein ratio in prepubertal constitutionally tall children

The height of subjects with constitutionally tall stature (CTS) is at least 2 SD above the mean of subjects of the same age and sex. Apart from a few discordant data on the role of GH and its direct mediator, IGF-I, no studies have been conducted on other components of the IGF system, which also condition the bioavailability and activity of IGF-I. We, therefore, investigated the possibility that other components of the IGF system might play a role in determining the increased growth velocity seen in CTS. To this end, we evaluated the behavior not only of IGF-I but also of IGF-II, IGF-binding protein (IGFBP)-3, and acid-labile subunit, the subunits that constitute the main IGF complex in circulation (150-kDa complex), as well as of IGFBP-1 and IGFBP-2, which are negatively regulated by GH and, like IGFBP-3, able to influence the bioavailability of the IGFs. The study was performed on 22 prepubertal subjects affected by CTS (16 males and 6 females), aged 2.8-13.3 yr (6.8 +/- 0.5 yr, mean +/- SEM). Thirty-seven normal prepubertal subjects (16 males and 21 females) aged between 2.2 and 13.3 yr (6.7 +/- 0.5 yr), who were comparable in socioeconomic and nutritional terms, served as controls. From the auxological point of view, subjects with CTS differed significantly from controls only in terms of growth velocity (HV-SD score; CTS, 1.8 +/- 0.3; controls, 0.4 +/- 0.2; P < 0.0001) and height (H-SD score; CTS, 3.1 +/- 0.1; controls, 0.4 +/- 0.2; P < 0.0001). The results demonstrated that the concentrations of IGF-I (27.3 +/- 2.0 nmol/liter), IGFBP-3 (66.9 +/- 3.8), and acid-labile subunit (216.8 +/- 13.6) in CTS-affected subjects were not significantly different from those determined in controls (25.0 +/- 2.9, 74.4 +/- 4.1, and 241.0 +/- 11.9, respectively). By contrast, IGF-II levels proved significantly higher in CTS subjects (IGF-II: 87.2 +/- 3.4 vs. 52.4 +/- 2.3, P < 0.0001). Chromatographic analysis, performed after acid treatment of pooled sera, showed only the presence of normal 7.5-kDa IGF-II in both CTS subjects and controls. In comparison with controls, CTS children showed a lower concentration of IGFBP-1 (1.6 +/- 0.3 vs. 4.1 +/- 0.7, P = 0.03) and a higher concentration of IGFBP-2 (14.3 +/- 1.8 vs. 9.6 +/- 1.1, P = 0.03). The IGFs (IGF-I and -II)/IGFBPs (-1 + -2 + -3) molar ratio was significantly higher (P < 0.0001) in CTS children than in controls. In particular, the IGF-II/IGFBP ratio (P < 0.0001) was responsible for the excess of the IGF peptide in relation to the concentrations of IGFBPs and, therefore, for the increase in the potentially bioactive free form of the IGFs. Moreover, the IGFBP-3/IGF molar ratio was significantly reduced, being less than 1 in CTS subjects (0.6 +/- 0.1 vs. 1.1 +/- 0.1), so that a quantity of IGF peptides lack sufficient IGFBP-3 to form the 150-kDa complex with which are normally sequestered in the vascular compartment. The data show that in CTS: 1) the most GH-dependent components of the IGF system are normal, consistent with the finding of a normal GH secretory state; 2) the less GH-dependent IGF-II is significantly increased, in agreement with the finding of a relationship between high levels of IGF-II and overgrowth in some syndromes; and 3) the IGF/IGFBP molar ratio is increased, and, therefore, a greater availability of free IGF for target tissues may be responsible for overgrowth in CTS.

Idiopathic short stature

Idiopathic short stature (ISS) is a term used to describe the status of children with short stature that cannot be attributed to a specific cause. Many children diagnosed as having ISS have partial GH insensitivity, which can result from disturbances at various points of the GH-IGF-I axis. Several clinical studies on spontaneous growth in ISS showed that adult height was almost in the range of target height. GH treatment led to adult height not significantly higher than the pretreatment predicted adult height in most reports. No metabolic side effects have been observed, even when the dose was higher than in GH deficiency. Manipulation of puberty with gonadotrophin releasing hormone analogues reported by a few authors in a small number of children has shown conflicting results. Long-term psychological benefits of GH therapy for short normal children have not been demonstrated to date.

Unresolved problems in optimal therapy of pubertal disorders in oncological and bone marrow transplanted patients

Specialised clinics for the long-term follow-up of survivors from childhood cancer have developed over recent years. The problems encountered among patients who received multiple chemotherapy and radiotherapy can be challenging and require high expertise and close collaboration among different professionals (e.g. oncologists, endocrinologists, radiotherapists, psychologists). Endocrine disorders are often seen, particularly among those who received cranial radiotherapy or gonadotoxic chemotherapy; puberty can be affected and the spectrum of disorders may range from precocious or accelerated puberty to delayed, arrested or even absent pubertal development. Growth impairment can be multifactorial and growth hormone deficiency is an important but probably not the only factor involved. Many questions remain about the optimal management of this group of young patients. In the consensus guidelines that follow the overview an attempt is made to help optimise patients' growth and puberty by suggesting practical clinical approaches to some of the most challenging issues.

Pyridostigmine and metoclopramide do not restore the TSH response to TRH inhibited by L-thyroxine treatment in children with goiter

To define the role of somatostatin and dopamine in TSH suppression induced by L-thyroxine, 16 children (12 F, 4 M) on suppressive doses of L-thyroxine (3-4 microg/kg/day) for endemic goiter were studied. Firstly a conventional TRH test was performed in all subjects, in order to evaluate TSH, PRL and GH (basal study). A week later a second TRH test was carried out; one hour before the test, however, group A (9 patients) was given 60 mg pyridostigmine bromide po (pyridostigmine study) and group B (7 patients) 10 mg metoclopramide po (metoclopramide study). In the basal study, TSH was suppressed in both groups and levels did not increase following TRH administration, while PRL increased significantly and GH levels remained stable. In the pyridostigmine study, TSH levels did not increase following TRH administration, while PRL and GH levels were both significantly raised. In the metoclopramide study, TSH and GH levels were not raised following TRH administration, while a significantly greater increase of PRL was observed. In conclusion, suppressive doses of L-thyroxine inhibit the TSH response to TRH, while they do not seem to affect GH and PRL secretion. Somatostatin and/or dopamine do not seem to play a significant role in the L-thyroxine-induced TSH suppression.

Growth hormone immunoreactivity does not reflect bioactivity

In childhood, the largest secretory burst of GH occurs during nighttime, and consists of a complex mixture of molecular forms of GH that are thought to have different biologic activity. Standard GH assays cannot distinguish between bioactive and biologically inactive GH isoforms. To examine this relationship, overnight GH secretion was assessed by blood sampling every 30 min in 10 short prepubertal children (7 boys and 3 girls) to evaluate both the serum concentration and the biologic activity of GH. Serum GH concentrations were measured by an immunofluorometric assay and its biologic activity by the Nb2 cell bioassay. The 12-h (2000 h to 0800 h) and 6-h (2000 h to 0200 h and 0200 h to 0800 h) GH profiles were analyzed using the Pulsar program. When GH secretory pattern was measured by immunofluorometric assay, the area under the curve above the 0 line, the mean GH concentration, and the mean height of the secretory peaks were significantly higher during the first than during the second part of the night (29.17+/-5.93 versus 16.29+/-1.87 mIU/L, p<0.05; 7.77+/-1.28 versus 4.83+/-0.33 mIU/L, p<0.05; 4.61+/-0.94 versus 2.68+/-0.27 mIU/L, p<0.05, respectively). In contrast, GH biologic activity was not significantly different during the two parts of the night. In conclusion, a dissociation between GH bioactivity and immunoreactivity is present in physiologic conditions, indicating that standard GH measurements do not provide any information on the biologic activity of the hormone. Although GH secretion is regulated by complex neuroendocrine mechanisms, the biologic activity of the hormone seems to be independent of them and is most probably regulated by peripheral mechanisms acting on its clearance or bioavailability to the target tissues.

Long-term follow-up evaluation of magnetic resonance imaging in the prognosis of permanent GH deficiency

OBJECTIVE

In patients with GH deficiency (GHD), magnetic resonance imaging (MRI) has revealed morphological abnormalities such as pituitary hypoplasia, pituitary stalk agenesis (PSA) and ectopia of the posterior pituitary (PPE). The MRI anomalies have been more frequently reported in patients with multiple pituitary hormone deficiency (MPHD) than in subjects with isolated GH deficiency (IGHD). The aim of this work was to define which MRI anatomical abnormalities of the hypothalamo-pituitary area can be considered as a prognostic marker of permanent GHD.

DESIGN

To investigate the relationship between the neuroradiological images and endocrine findings, we clinically re-evaluated 93 out of the 121 GHD patients with IGHD and MPHD previously studied.

RESULTS

No additional hormone deficiencies were observed in 55 out of 60 patients initially classified as having IGHD with a normal (15 cases) or reduced (40 cases) pituitary gland size, without other MRI abnormalities. The remaining five children, who had initially shown an apparently IGHD in spite of PSA and PPE, developed a MPHD over time. In 33 MPHD patients with (25 cases) or without (8 cases) MRI abnormalities, the associated hormone deficiencies were confirmed during follow-up.

CONCLUSIONS

The IGHD patients showing PSA and PPE inevitably develop additional hormone deficiencies, while IGHD subjects having no MRI abnormalities maintain IGHD. Moreover, the anatomical abnormalities of the hypothalamo-pituitary area can be considered as a prognostic marker of permanent GHD.

Isochromosome (7)(q10) in Shwachman syndrome without MDS/AML and role of chromosome 7 anomalies in myeloproliferative disorders

Shwachman syndrome (SS) is an autosomal recessive disorder in which bone marrow dysfunction is observed, with development of myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML) in up to one third of the cases. Inconclusive data are available as to increased chromosome breakage in SS, while chromosome 7 anomalies, and often an isochromosome (7)(q10), are frequent in cases with MDS/AML. We report on the consistent presence of an i(7)(q10) in the bone marrow and blood lymphocytes in one of two sisters affected with SS without any clinical or cytological signs of MDS/AML. Thus, this patient was either a case of constitutional mosaicism for the i(7)(q10), or this had to be acquired in a nondysplastic and non-neoplastic marrow clone. DNA polymorphism analysis demonstrated the paternal origin of the i(7q). We postulate that the SS mutation acts as a mutator gene, and causes karyotype instability; abnormal clones would thus arise in the marrow, and chromosome 7 anomalies, i(7q) in particular, will in turn lead to MDS/AML. If this interpretation is correct, it would be also an indication to consider chromosome 7 anomalies in general, out of SS, as primary changes in MDS/AML pathogenesis.

Response to long-term hGH therapy in two children with Schwachman-Diamond syndrome associated with GH deficiency

Schwachman-Diamond syndrome is a rare congenital disorder characterized by pancreatic insufficiency, metaphyseal anomalies, recurrent infections, hematologic abnormalities, and growth retardation. Slow growth in these patients has been attributed to nutritional deficits, recurrent infections, and skeletal anomalies. Two cases of Schwachman-Diamond syndrome associated with growth hormone deficiency have been previously reported. We report here on 2 additional cases with this unusual association. Therefore, growth failure in Schwachman-Diamond syndrome should not be assumed to be due to chronic illness or recurrent infections; other etiologies for growth failure should be sought. However, the presence of metaphyseal disorders probably interferes with the long-term efficacy of growth hormone substitutive therapy.