Insulin-like growth factor I (IGF-I) and IGF-binding protein 3 as diagnostic markers of growth hormone deficiency in infancy

Estimation of the reference values and decision limits for growth hormone in newborns using dried blood spots

OBJECTIVES

Severe deficiency of growth hormone (GHD) of the newborn is a rare but potentially life-threatening disease. GH measured during the first week of life, using dried blood spots (DBS), may offer several advantages. Aim of the study was to estimate the reference values for GH in newborns by a new analytical method using DBS.

METHODS

Using a new developed analytical method, GH was estimated from DBS of 1,036 healthy newborns attending the Neonatology Unit of Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico of Milan in the period July-October 2021. Reference values for GH deficiency were estimated by the Harrell-Davis bootstrap method, with 90 %CI calculated by the bias-corrected and accelerated bootstrap method.

RESULTS

All GH measurements required 33 analytical sessions (8 months) with a CV% for calibration curve slopes equal to 6.9 %. Intermediate precision evaluated by measurement of low (3 μg/L) and high (10 μg/L) quality controls was, respectively, 14 and 6.5 %. GH reference values, estimated at percentiles 1.0st, 2.5th and 5.0th, and their 90 %CI, were, respectively, 4.5 μg/L (90 %CI 3.8-5.1), 5.9 μg/L (90 %CI 5.4-6.4) and 7.0 μg/L (90 %CI 6.7-7.3). GH levels were not associated with sex, standard deviation scores, birth weight, gestational age, type of delivery or mother's variables (age, smoking habit, gestational diabetes).

CONCLUSIONS

Validation data suggest that this method can be used to measured GH in newborns using DBS. The reference values estimated in this study are in accordance with previous published works using ELISA and may help confirming the clinical suspicion of neonatal GHD.

Short and Long-Term Effects of Growth Hormone in Children and Adolescents With GH Deficiency

The syndrome of impaired GH secretion (GH deficiency) in childhood and adolescence had been identified at the end of the 19th century. Its non-acquired variant (naGHD) is, at childhood onset, a rare syndrome of multiple etiologies, predominantly characterized by severe and permanent growth failure culminating in short stature. It is still difficult to diagnose GHD and, in particular, to ascertain impaired GH secretion in comparison to levels in normally-growing children. The debate on what constitutes an optimal diagnostic process continues. Treatment of the GH deficit via replacement with cadaveric pituitary human GH (pit-hGH) had first been demonstrated in 1958, and opened an era of therapeutic possibilities, albeit for a limited number of patients. In 1985, the era of recombinant hGH (r-hGH) began: unlimited supply meant that substantial long-term experience could be gained, with greater focus on efficacy, safety and costs. However, even today, the results of current treatment regimes indicate that there is still a substantial fraction of children who do not achieve adult height within the normal range. Renewed evaluation of height outcomes in childhood-onset naGHD is required for a better understanding of the underlying causes, whereby the role of various factors - diagnostics, treatment modalities, mode of treatment evaluation - during the important phases of child growth - infancy, childhood and puberty - are further explored.

Effects of improved water, sanitation, and hygiene and improved complementary feeding on environmental enteric dysfunction in children in rural Zimbabwe: A cluster-randomized controlled trial

BACKGROUND

Environmental enteric dysfunction (EED) may be an important modifiable cause of child stunting. We described the evolution of EED biomarkers from birth to 18 months in rural Zimbabwe and tested the independent and combined effects of improved water, sanitation, and hygiene (WASH), and improved infant and young child feeding (IYCF), on EED.

METHODOLOGY AND FINDINGS

The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial was a 2x2 factorial cluster-randomised trial of improved IYCF and improved WASH on child stunting and anaemia at 18 months of age. 1169 infants born to HIV-negative mothers provided plasma and faecal specimens at 1, 3, 6, 12, and 18 months of age. We measured EED biomarkers that reflect all domains of the hypothesized pathological pathway. Markers of intestinal permeability and intestinal inflammation declined over time, while markers of microbial translocation and systemic inflammation increased between 1-18 months. Markers of intestinal damage (I-FABP) and repair (REG-1β) mirrored each other, and citrulline (a marker of intestinal epithelial mass) increased from 6 months of age, suggesting dynamic epithelial turnover and regeneration in response to enteric insults. We observed few effects of IYCF and WASH on EED after adjustment for multiple comparisons. The WASH intervention decreased plasma IGF-1 at 3 months (β:0.89, 95%CI:0.81,0.98) and plasma kynurenine at 12 months (β: 0.92, 95%CI:0.87,0.97), and increased plasma IGF-1 at 18 months (β:1.15, 95%CI:1.05,1.25), but these small WASH effects did not translate into improved growth.

CONCLUSIONS

Overall, we observed dynamic trends in EED but few effects of IYCF or WASH on biomarkers during the first 18 months after birth, suggesting that these interventions did not impact EED. Transformative WASH interventions are required to prevent or ameliorate EED in low-income settings.

New Insights in Growth Hormone Stimulation Tests Protocols

Objective: The objective of this study was to analyze the performance of 2 stimulation tests used in the diagnosis of growth hormone deficiency.

Method: A retrospective study was conducted on a non-random sample of 310 patients, between 2 and 20 years old, who were hospitalized in the Mureș County Hospital’s Endocrinology Department and in the National Institute of Endocrinology C.I. Parhon with short stature between 2009-2015. Inclusion criteria: all subjects who underwent growth hormone stimulation tests in accordance with the national protocol. Microsoft Office Excel was used for data collection and MedCalc v 12.5 was used for statistical analysis.

Results: From the total of 310 patients, 102 were diagnosed in Târgu Mureș and 208 in Bucharest. Sex ratio favored boys (boys:girls 1.64:1). In 173 subjects growth hormone deficiency was confirmed. For both tests the percentage of maximum response was the highest for the 60 minutes blood sample regardless if the test were positive or not. Both tests have 100% sensitivity and negative predictive value, with the highest specificity for the 60 minutes clonidine and 30 minutes insulin. The false positive rate was 60% for the insulin test and 27.2% for clonidine for Târgu Mureș sample and 86.9% for the insulin test and 62.5% for clonidine for Bucharest sample. The concordance of the 2 tests was 49.36%.

Conclusions: Stimulating growth hormone testing has a number of limitations but is still needed in some auxological circumstances. We recommend performing the clonidine test first to exclude idiopathic short stature and then the insulin tolerance test for the diagnosis of growth hormone deficiency.

Diagnostic value of serum IGF-1 and IGFBP-3 in growth hormone deficiency: a systematic review with meta-analysis

Serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) are conventionally considered available for the diagnosis of growth hormone deficiency (GHD), but the results about their diagnostic values are inconsistent among some recent epidemiological studies. The aim of this study is to assess the diagnostic values of serum IGF-1 and IGFBP-3 for GHD by conducting a systematic review and meta-analysis. Studies on serum IGF-1 and IGFBP-3 used in GHD diagnosis were systematically searched from databases PubMed, EMBASE, and CNKI (up to December 2013). Characteristics of the studies and data were independently collected according to the inclusion criteria by two authors. The quality of included studies was assessed using quality assessment of diagnostic accuracy studies (QUADAS). Both sensitivity (SEN) and specificity (SPE) of IGF-1 and IGFBP-3 in GHD diagnosis were estimated on statistical software Meta-DiSc and Stata. A total of 12 studies were included for the final analysis. IGF-1 had SEN of 0.66, SPE of 0.69, positive likelihood ratio (PLR) of 2.48, negative likelihood ratio (NLR) of 0.51, area under the summary receiver operating characteristic curve (SROC) of 0.78, and Q* value of 0.72. Serum IGFBP-3 had SEN of 0.50, SPE of 0.79, PLR of 2.69, NLR of 0.64, area under SROC of 0.80, and Q* value of 0.73.

CONCLUSION

Serum IGF-1 and IGFBP-3 are useful for the diagnosis of GHD and can be utilized as auxiliary diagnosis indexes for provocative test.

Pituitary function in children following infectious diseases of the central nervous system

Recent studies in adults suggest that pituitary deficiencies develop in a considerable proportion of patients who recover from infectious meningitis. The aim of this study was to evaluate pituitary function of children with a history of meningitis. Seventy-nine children were admitted to the Safra Children's Hospital due to meningitis between 2007 and 2010. Twenty-four families were lost for follow-up, 55 were interviewed by phone and 14 (9 males) participated in the study. Evaluation included medical history, physical examination, auxological measurements and basal levels of TSH, fT4, cortisol and IGF1. Children with abnormal results were followed for a year and dynamic testing was performed when indicated. Mean age at time of infectious meningitis was 3.8 ± 5.4 years (range 0.03-15.8), and at clinical evaluation 6.4 ± 6.4 (range 1.2-20). The interval between the acute event and evaluation was 2.7 ± 1.2 years. Thyroid function tests and basal cortisol levels were normal for all children. Three children had low IGF1 levels; however over a year of follow-up two of them had normal height and growth velocity, making growth hormone deficiency unlikely. One child had low height SDS, but exhibited a normal response to a growth hormone stimulation test. Pituitary dysfunction with overt clinical symptoms is not a frequent consequence of acute meningitis in children. Follow-up of growth and puberty of children post-meningitis by the primary care physician is probably sufficient. Invasive assessments should be reserved for selected cases where there is slow growth or other clinical suspicion of hypopituitarism.

Stunting is characterized by chronic inflammation in Zimbabwean infants

BACKGROUND

Stunting affects one-third of children in developing countries, but the causes remain unclear. We hypothesized that enteropathy leads to low-grade inflammation, which suppresses the growth hormone-IGF axis and mediates stunting.

METHODS

We conducted a case-control study of 202 HIV-unexposed Zimbabwean infants who were stunted (height-for-age Z-score (HAZ) <-2; cases) or non-stunted (HAZ >-0.5; controls) at 18 months. We measured biomarkers of intestinal damage (I-FABP), inflammation (CRP, AGP, IL-6) and growth hormone-IGF axis (IGF-1, IGFBP3) in infant plasma at 6 weeks and 3, 6, 12 and 18 months, and in paired maternal-infant plasma at birth. Adjusted mean differences between biomarkers were estimated using regression models. Multivariate odds ratios of stunting were estimated by logistic regression.

RESULTS

At birth, cases were shorter (median (IQR) HAZ -1.00 (-1.53, -0.08) vs 0.03 (-0.57, 0.62,); P<0.001) than controls and their mothers had lower levels of IGF-1 (adjusted mean difference (95%CI) -21.4 (-39.8, -3.1) ng/mL). From 6 weeks to 12 months of age, levels of CRP and AGP were consistently higher and IGF-1 and IGFBP3 lower in cases versus controls; IGF-1 correlated inversely with inflammatory markers at all time-points. I-FABP increased between 3-12 months, indicating extensive intestinal damage during infancy, which was similar in cases and controls. In multivariate analysis, higher log10 levels of CRP (aOR 3.06 (95%CI 1.34, 6.99); P = 0.008) and AGP (aOR 7.87 (95%CI 0.74, 83.74); P = 0.087) during infancy were associated with stunting. There were no associations between levels of I-FABP, IL-6, sCD14 or EndoCAb and stunting.

CONCLUSIONS

Stunting began in utero and was associated with low maternal IGF-1 levels at birth. Inflammatory markers were higher in cases than controls from 6 weeks of age and were associated with lower levels of IGF-1 throughout infancy. Higher levels of CRP and AGP during infancy were associated with stunting. These findings suggest that an extensive enteropathy occurs during infancy and that low-grade chronic inflammation may impair infant growth.

Associations of IGF-1 gene variants and milk protein intake with IGF-I concentrations in infants at age 6 months - results from a randomized clinical trial

OBJECTIVE

The interplay of genetic and nutritional regulation of the insulin-like growth factor-I axis in children is unclear. Therefore, potential gene-nutrient effects on serum levels of the IGF-I axis in a formula feeding trial were studied.

DESIGN

European multicenter randomized clinical trial of 1090 term, formula-fed infants assigned to receive cow's milk-based infant and follow-on formulae with lower (LP: 1.25 and 1.6 g/100 mL) or higher (HP: 2.05 and 3.2 g/100 mL) protein contents for the first 12 months of life; a comparison group of 588 breastfed infants (BF) was included. Eight single nucleotide polymorphisms (SNPs) of the IGF-1-(rs6214, rs1520220, rs978458, rs7136446, rs10735380, rs2195239, rs35767, and rs35766) and two of the IGFBP-3-(rs1496495, rs6670) gene were analyzed. Serum levels of total and free IGF-I, IGFBP-3 and the molar ratio IGF-1/IGFBP-3 at age 6 months were regressed on determined SNPs and feeding groups in 501 infants.

RESULTS

IGF-1-SNPs rs1520220, rs978458, and rs2195239 significantly increased total-IGF-I and molar-ratio IGF-I/IGFBP-3 by ~1.3 ng/mL and ~1.3 per allele, respectively; compared to LP infants concentration and molar-ratio were increased in HP by ~1.3 ng/mL and ~1.3 and decreased in BF infants by ~0.6 ng/mL and ~0.6, respectively. IGFBP-3 was only affected by the BF group with ~450 ng/mL lower levels than the LP group. No gene-feeding-group interaction was detected for any SNP, even without correction for multiple testing.

CONCLUSIONS

Variants of the IGF-1-gene play an important role in regulating serum levels of the IGF-I axis but there is no gene-protein-interaction. The predominant nutritional regulation of IGF-I and IGFBP-3 gives further evidence that higher protein intake contributes to metabolic programming of growth.

Male hypogonadism: an extended classification based on a developmental, endocrine physiology-based approach

Normal testicular physiology results from the integrated function of the tubular and interstitial compartments. Serum markers of interstitial tissue function are testosterone and insulin-like factor 3 (INSL3), whereas tubular function can be assessed by sperm count, morphology and motility, and serum anti-Müllerian hormone (AMH) and inhibin B. The classical definition of male hypogonadism refers to testicular failure associated with androgen deficiency, without considering potential deficiencies in germ and Sertoli cells. Furthermore, the classical definition does not consider the fact that low basal serum testosterone cannot be equated to hypogonadism in childhood, because Leydig cells are normally quiescent. A broader clinical definition of hypogonadism that could be applied to male patients in different periods of life requires a comprehensive consideration of the physiology of the hypothalamic-pituitary-testicular axis and its disturbances along development. Here we propose an extended classification of male hypogonadism based on the pathophysiology of the hypothalamic-pituitary-testicular axis in different periods of life. The clinical and biochemical features of male hypogonadism vary according to the following: (i) the level of the hypothalamic-pituitary-testicular axis primarily affected: central, primary or combined; (ii) the testicular cell population initially impaired: whole testis dysfunction or dissociated testicular dysfunction, and: (iii) the period of life when the gonadal function begins to fail: foetal-onset or postnatal-onset. The evaluation of basal testicular function in infancy and childhood relies mainly on the assessment of Sertoli cell markers (AMH and inhibin B). Hypergonadotropism should not be considered a sine qua non condition for the diagnosis of primary hypogonadism in childhood. Finally, the lack of elevation of gonadotropins in adolescents or adults with primary gonadal failure is indicative of a combined hypogonadism involving the gonads and the hypothalamic-pituitary axis.

Analysis of the GH content within archived dried blood spots of newborn screening cards from children diagnosed with growth hormone deficiency after the neonatal period

OBJECTIVE

It is unknown whether GH secretion of children with growth hormone deficiency (GHD) is already diminished at birth. We aimed to determine the GH content within archived dried blood spots of newborn screening cards from children diagnosed with GHD at childhood.

DESIGN

At our hospital, all children with the diagnosis of GHD and an actual age <10years were identified. For 16 patients (mean age, 7.4years; range, 1.0-9.7), screening cards were available. The archived dried blood from the first 48 to 96h of life was eluated in buffer of a highly sensitive hGH-ELISA to measure the GH content. Reference values were calculated based on 600 anonymous newborn screening cards of different ages.

RESULTS

Median GH content within the archived dried blood spots of the reference had declined by 30% during the first year and by further 35% during the next 8.5years of storage. After correction for time of storage, four out of the 16 archived dried blood spots of the GHD children contained low amounts of GH (≤5th percentile). Diminished GH secretion at birth was absent in isolated GHD, but associated with multiple pituitary hormone deficiency (MPHD) (P=0.0013), ectopic neurohypophysis (P=0.0013), lower GH test peak values (P=0.02) and higher weight at diagnosis (P=0.015).

CONCLUSIONS

Children with isolated GHD have normal GH secretory capacity during the first week of life while the majority of children with MPHD and pituitary malformation were GH deficient immediately after birth.

Does plasma IGF-BP3 measurement contribute to the diagnosis of growth hormone deficiency in children?

OBJECTIVE

To audit the contribution of plasma IGF-PB3 measurement to the diagnosis of growth hormone deficiency (GHD) in children.

POPULATION AND METHODS

Retrospective case study including boys and girls aged 0 to 18 years who attended our paediatric endocrinology clinic for short stature and/or post-irradiation follow-up, and had at least one GH provocative testing. Children with hypothyroidism, Laron or Kowarski syndromes, severe malnutrition, chronic renal failure and liver failure were excluded.

RESULTS

Fifty-eight children were enrolled and grouped as GHD [+] (19 cases) and GDH [-] (39 cases). IGF-I and IGF-BP3 assay was carried out in 88% and 62% cases respectively, both groups were comparable for age, sex, BMI, target height, pubertal stage and bone age. There was a significant difference in peak GH between GDH [-] and GHD [+] groups (41.8 mUI/L ± 21.7 versus 11.5 ± 5.9 mUI/L, P<0.00001, respectively). No difference was found between groups with regards to IGF-I Z-scores and IGF-BP3 Z-scores. There was, however, a positive correlation between IGF-I Z-scores and IGF-BP3 Z-scores (r=0.50; P<0.0016). IGF-BP3 measurement could not differentiate between GHD [+] and GHD [-] groups.

CONCLUSIONS

Measurement of plasma IGF-BP3 level contributes poorly to the diagnosis of GHD. We do not recommend it in routine use.

Reference values of IGF-I in children from birth to 5 years of age, in Burkina Faso, using blood samples on filter paper

OBJECTIVES

The aims of this study were to validate the use of filter paper to measure insulin-like growth factor-I (IGF-I) and to establish normal levels of IGF-I in children appearing healthy, from birth to 5 years of age in an African population.

METHODS

We determined IGF-I from blood collected on filter paper. We validated this method by comparing the IGF-I values from dried blood spots on filter paper (kept at 4 degrees C and ambient temperature) and from serum among 13 children under 5. IGF-I were measured by the classical IGF-I RIA, after separation of the IGF-I from its binding proteins, using Sep-Pak chromatography. To establish normal levels of IGF-I, we conducted a cross-sectional study and collected blood samples with filter paper among 360 children in Ouagadougou (Burkina Faso).

RESULTS

IGF-I determined from dried blood spots on filter paper were in good agreement with IGF-I levels obtained from blood serum, whether the filter papers were kept at 4 degrees C or at ambient temperature. The results of IGF-I-levels in apparently healthy children showed that geometric mean IGF-I ranged from 27 microg/l in boys younger than five months to 31 microg/l in 5-year-old boys. In girls, mean IGF-I ranged from 29 microg/l for girls younger than five months to 45 microg/l at the age of 5. From birth to 24 months, IGF-I decreased by 0.32+/-0.08 microg/l/month in boys and by 0.27+/-0.06 microg/l/month in girls and these decreases were not significantly different (p=0.95). After the age of 24 months, there was an increase in IGF-I of 4.9+/-1.3 microg/l/year in boys and of 8.4+/-0.8 microg/l/year in girls. This increase was indeed significantly different (p<0.001).

CONCLUSIONS

Reference values of IGF-I for African boys and girls were determined. They will be used for endocrine evaluations and nutritional monitoring.

Selecting short-statured children needing growth hormone testing: derivation and validation of a clinical decision rule

Background

Numerous short-statured children are evaluated for growth hormone (GH) deficiency (GHD). In most patients, GH provocative tests are normal and are thus in retrospect unnecessary.

Methods

A retrospective cohort study was conducted to identify predictors of growth hormone (GH) deficiency (GHD) in children seen for short stature, and to construct a very sensitive and fairly specific predictive tool to avoid unnecessary GH provocative tests. GHD was defined by the presence of 2 GH concentration peaks < 10 ng/ml. Certain GHD was defined as GHD and viewing pituitary stalk interruption syndrome on magnetic resonance imaging. Independent predictors were identified with uni- and multi-variate analyses and then combined in a decision rule that was validated in another population.

Results

The initial study included 167 patients, 36 (22%) of whom had GHD, including 5 (3%) with certain GHD. Independent predictors of GHD were: growth rate < -1 DS (adjusted odds ratio: 3.2; 95% confidence interval [1.3–7.9]), IGF-I concentration < -2 DS (2.8 [1.1–7.3]) and BMI z-score ≥ 0 (2.8 [1.2–6.5]). A clinical decision rule suggesting that patients be tested only if they had a growth rate < -1 DS and a IGF-I concentration < -2 DS achieved 100% sensitivity [48–100] for certain GHD and 63% [47–79] for GHD, and a specificity of 68% [60–76]. Applying this rule to the validation population (n = 40, including 13 patients with certain GHD), the sensitivity for certain GHD was 92% [76–100] and the specificity 70% [53–88].

Conclusion

We have derived and performed an internal validation of a highly sensitive decision rule that could safely help to avoid more than 2/3 of the unnecessary GH tests. External validation of this rule is needed before any application.

Idiopathic short stature: definition, epidemiology, and diagnostic evaluation

Idiopathic short stature is a condition in which the height of the individual is more than 2 SD below the corresponding mean height for a given age, sex and population, in whom no identifiable disorder is present. It can be subcategorized into familial and non-familial ISS, and according to pubertal delay. It should be differentiated from dysmorphic syndromes, skeletal dysplasias, short stature secondary to a small birth size (small for gestational age, SGA), and systemic and endocrine diseases. ISS is the diagnostic group that remains after excluding known conditions in short children.

Assessment of serum IGF-I concentrations in the diagnosis of isolated childhood-onset GH deficiency: a proposal of the Italian Society for Pediatric Endocrinology and Diabetes (SIEDP/ISPED)

The diagnosis of GH deficiency (GHD) is based on the measurement of peak GH responses to pharmacological stimuli. Pharmacological stimuli, however, lack precision, accuracy, are not reproducible, are invasive, non-physiological and some may even be hazardous. Furthermore, different GH commercial assays used to measure GH in serum yield results that may differ considerably. In contrast to GH, IGF-I can be measured on a single, randomly-obtained blood sample. A review of the available data indicates that IGF-I measurement in the diagnosis of childhood-onset isolated GHD has a specificity of up to 100%, with a sensitivity ranging from about 70 to 90%. We suggest an algorithm in which circulating levels of IGF-I together with the evaluation of auxological data, such as growth rate and growth, may be used to assess the likelihood of GHD in pre-pubertal children.