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SPECIAL ARTICLE |
* Pennsylvania State University College of Medicine, Hershey Medical Center, Hershey, Pennsylvania
Children’s Hospital Medical Center, University of Cincinnati School of Medicine, Cincinnati, Ohio
Sophia Children’s Hospital, Erasmus University of Rotterdam, Rotterdam, the Netherlands
|| University Saint-Louis Lariboisière, Hôpital Robert Debré, Paris, France
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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Methods. A 13-member independent panel of pediatric endocrinologists was convened to discuss relevant issues with respect to definition, diagnosis, and clinical management of short children born SGA. Panel members convened over a series of 3 meetings to thoroughly review, discuss, and come to consensus on the identification and treatment of short children who are born SGA.
Conclusions. SGA is defined as birth weight and/or length at least 2 standard deviations (SDs) below the mean for gestational age (
–2 SD). Accurate gestational dating and measurement of birth weight and length are crucial for identifying children who are born SGA. Comprehensive pregnancy, perinatal, and immediate postnatal data may help to confirm the diagnosis. Maternal, placental, and fetal causes of SGA should be sought, although the cause is often not clear. Most children who are SGA experience catch-up growth and achieve a height >2 SD below the mean; this catch-up process is usually completed by the time they are 2 years of age. A child who is SGA and older than 3 years and has persistent short stature (ie, remaining at least 2 SD below the mean for chronologic age) is not likely to catch up and should be referred to a pediatrician who has expertise in endocrinology. Bone age is not a reliable predictor of height potential in children who are SGA. Nevertheless, a standard evaluation for short stature should be performed. A diagnosis of SGA does not exclude growth hormone (GH) deficiency, and GH assessment should be performed if there is clinical suspicion or biochemical evidence of GH deficiency. At baseline, insulin-like growth factor-I, insulin-like growth factor binding protein-3, fasting insulin, glucose, and lipid levels as well as blood pressure should be measured, and all aspects of SGA—not just stature—should be addressed with parents. The objectives of GH therapy in short children who are SGA are catch-up growth in early childhood, maintenance of normal growth in childhood, and achievement of normal adult height. GH therapy is effective and safe in short children who are born SGA and should be considered in those older than 2 to 3 years. There is long-term experience of improved growth using a dosage range from 0.24 to 0.48 mg/kg/wk. Higher GH doses (0.48 mg/kg/wk [0.2 IU/kg/d]) are more effective for the short term. Whether the higher GH dose is more efficacious than the lower dose in terms of adult height results is not yet known. Only adult height results of randomized dose-response studies will give a definite answer. Monitoring is necessary to ensure safety of medication. Children should be monitored for changes in glucose homeostasis, lipids, and blood pressure during therapy. The frequency and intensity of monitoring will vary depending on risk factors such as family history, obesity, and puberty.
Key Words: small for gestational age • intrauterine growth retardation • catch-up growth • short stature • growth hormone
Abbreviations: SGA, small for gestational age • SD, standard deviation • GH, growth hormone • AGA, appropriate for gestational age • SDS, standard deviation score • IUGR, intrauterine growth retardation • IGF-I, insulin-like growth factor-I • IGFBP-3, insulin-like growth factor binding protein-3
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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–2 SD) for the infant’s gestational age, based on data derived from a reference population. SGA has also been defined in some publications as birth weight or length below the 10th, 5th, or 3rd percentile for gestational age. Although segregation of SGA from normal is somewhat arbitrary, <–2 SD was selected because it likely encompasses the majority of patients with disordered fetal growth and because most studies that have defined postnatal growth patterns and response to growth-promoting therapies have selected patients whose birth size is approximately –2 SD or less. Gestational age is most accurately gauged with the use of ultrasonography during pregnancy1 and the date of the last menstrual period. Ultrasonographic fetal indices such as crown-rump length during the first trimester correlate well with gestational age,2 but they must be recorded accurately and birth length must subsequently be measured precisely for a correct diagnosis of SGA to be made from these data. In addition, crown-rump length and gestational age are well correlated only when no growth defect has occurred during the first trimester. If a growth defect has occurred during the first trimester, then crown-rump length becomes a less reliable indicator of gestational age and last menstrual period is an important measure.
In 1999, the most recent year for which adult birth data are available from the National Center for Health Statistics, 3 959 417 infants were born in the United States.3 Using a 2.3% definition of SGA (–2 SD is equivalent to the 2.3 percentile), one can calculate that 
91 000 infants in the United States are born SGA annually. By comparison, the same cohort would produce only 800 female infants with Turner syndrome (assuming an incidence of 1 in 2500 female births) and 1100 individuals with growth hormone (GH) deficiency (incidence of 1 in 3500). A Swedish study found that among 3650 healthy full-term neonates born in 1973, 1974, or 1975, 5.4% (198) were SGA, defined as <–2 SD for birth length and/or height.4 Among those who were born SGA, 1.5% were both light and short, 2.4% were short only, and 1.6% were light only. Thus, compared with the incidence of other growth disorders, the incidence of SGA births is relatively high.
Some children who are born SGA fail to manifest spontaneous catch-up growth. Persistent short stature has been associated with psychosocial disadvantages and behavioral problems in individuals who may or may not also have cognitive impairment.5–13 For example, one study showed that absence of catch-up growth among male infants who were born SGA was the most important predictor of subnormal performance on standard psychological tests.13 In addition, adverse metabolic outcomes such as hypercholesterolemia may be related to failure to achieve catch-up.14
The International SGA Advisory Board Panel met in April, July, and October 2001 to discuss the definition of SGA, diagnosis and cause of SGA, catch-up growth among children who are born SGA, evaluation before GH therapy, and the role of GH therapy in the treatment of short children who are born SGA. This independent panel considered the scientific evidence and subsequently drafted this consensus statement on the treatment of short children who are born SGA, which addresses the following issues:
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HOW SHOULD SGA BE DEFINED? |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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–2 SD) for gestational age, which is approximately the third percentile for gestational age.15 Stated differently, neonates with either low birth weight or length or both for gestational age should be considered SGA. Accordingly, subject to available data, those who are born SGA may be further classified as SGAW (low birth weight), SGAL (low birth length), or SGAWL (low birth weight and length).4 It is important to describe these classifications, as different SGA subsets may respond differently to GH therapy. The term "SGA" refers not to fetal growth but to the size of the infant at birth; the term "intrauterine growth retardation" (IUGR) suggests diminished growth velocity in the fetus as documented by at least 2 intrauterine growth assessments.16 SGA and IUGR are not synonymous. IUGR indicates the presence of a pathophysiologic process occurring in utero that inhibits fetal growth. A child who is born SGA has not necessarily suffered from IUGR, and infants who are born after a short period of IUGR are not necessarily SGA.
Accurate classification of infants who are SGA depends on access to the appropriate reference data for birth weight and birth length available for the population, and country- or ethnic-specific normative data are important for identifying those at risk. In the United States, the most commonly used data on intrauterine growth come from charts developed by Usher and McLean.17 However, such data do not exist in many countries, and efforts should be made to improve the existing standard reference data. Although population-specific birth weight and birth length standards are important for identifying those who are born SGA, the accuracy of birth weight and length measurements and, particularly, of gestational dating is more crucial. Pediatricians should be encouraged to ask parents whether ultrasonographic dating was performed during pregnancy. Data are not available for male or female infants separately, and such would not seem to be necessary for purposes of diagnosing SGA. Furthermore, although data are not available for multiple births, the same standards should apply for these children in terms of expected catch-up growth and height, although multiple births may be the cause of the diminished birth weights.
In certain situations, it may be difficult to distinguish between neonates who are SGA and AGA, especially when gestational age data are unavailable or less than accurate. In addition, some very premature (gestational age <30 weeks) infants who are AGA and have very low birth weight may exhibit early postnatal growth failure. Pediatricians must be aware that early postnatal growth curves for these infants may mimic those for infants who are born SGA. Early postnatal growth data may be helpful to confirm the birth data, and comprehensive data from pregnancy and from perinatal and immediate postnatal states should be obtained and recorded.
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HOW SHOULD THE CAUSES OF SGA BE IDENTIFIED? |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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Impaired fetal growth has multiple causes, including a number of maternal, placental, and fetal factors (see Table 1).18–21 Maternal factors include age, parity, medical conditions such as hypertension, infections (particularly toxoplasmosis, rubella, cytomegalovirus, and herpesvirus), malnutrition, alcohol abuse, and cigarette smoking. Placental factors involve any mismatch between placental perfusion and fetal oxygenation.18 Examination of the placenta by a pathologist could help to define specific causes, including vascular. Fetal factors include chromosomal abnormalities and genetic defects. Specialized genetic tests and/or consultation with a geneticist may be valuable. A standard questionnaire, incorporating a core list of causes, should be developed to assist obstetricians, neonatologists, general pediatricians, and primary care physicians in determining the cause of SGA as early and as accurately as possible.
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HOW SHOULD CATCH-UP GROWTH BE DEFINED? |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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Most children who are born SGA experience catch-up growth and will achieve a height >–2 SD. Catch-up is typically an early postnatal process that in most SGA infants is completed by the age of 2 years;24,25 within this 2-year period, premature SGA infants (<37 weeks’ gestation) may take longer to catch up than full-term SGA infants.26 In >80% of infants who are born SGA, catch-up growth occurs during the first 6 months of life.27 For this reason, growth monitoring during the early postnatal period provides useful information; different growth patterns may be identified in infants as young as 3 months.
Approximately 10% of children born SGA will remain –2 SD for height throughout childhood and adolescence and into adulthood.27,28 Among children who are born SGA and do not achieve catch-up by 2 years of age, the relative risk of short stature (<–2 SD) at 18 years of age is 5.2 for those with low birth weight and 7.1 for those with low birth length.25 Therefore, a short child who was born SGA and has not caught up by 2 to 3 years of age and whose catch-up growth has stopped should be referred to a pediatrician who has expertise in endocrinology.
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HOW SHOULD SHORT CHILDREN WHO WERE BORN SGA BE EVALUATED BEFORE STARTING GH THERAPY? |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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Whether measures of GH secretion provide clinically useful information for the routine treatment of short children who were born SGA is controversial. Arguments that favor evaluation for GH deficiency stem from data suggesting that many short patients who were born SGA have diminished GH output, as evidenced by low levels of spontaneous GH secretion31–36 and depressed circulating concentrations of markers of GH secretion, such as insulin-like growth factor-I (IGF-I).33,37 Thus, the lack of catch-up growth in some cases might be attributable to reduced GH secretion. Tests of GH release might, in theory, be used to predict response to different therapeutic regimens in addition to being used to identify an underlying pathologic condition. However, distinguishing normal from abnormal pituitary function by GH testing is frequently not straightforward,38,39 and standard GH stimulation tests (eg, arginine, insulin-induced hypoglycemia) do not predict growth response in most short patients who are SGA and treated with GH at doses now accepted as generally efficacious.37,40–42 Furthermore, GH deficiency cannot explain all growth deficits, because children who are born with severe congenital GH deficiency are usually not born SGA. Thus, mandating direct measurement of GH secretion, either spontaneous or in response to provocative agents, for all short children who are born SGA is not adequately justified by current published data. The present recommendation is that tests of GH release be performed when GH deficiency is suspected on clinical or biochemical grounds. Accordingly, measurement of circulating concentrations of IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) before the start of GH therapy not only provides a baseline against which to assess the biochemical response to GH therapy but also serves as a useful screen for possible GH deficiency in this patient population.
Although insulin resistance is not an unexpected finding among children who are SGA and have become obese, insulin resistance may be present in short children who are SGA43 and, subsequently, in young adults who were born SGA.28 Eight percent of 8-year-old children were found to have an abnormal glucose tolerance test, although over the subsequent 10 years none developed diabetes mellitus.44 The majority of prepubertal children who are SGA are not at risk for glucose intolerance. Because insulin resistance may increase during GH therapy, parents should be asked whether there is a family history of type 2 diabetes, although any potential long-term risk as a consequence of elevated insulin levels is unknown. In lean children without a family history of diabetes, screening of the carbohydrate status (eg, fasting, postprandial glucose and insulin levels) is suitable. More stringent measures are recommended for those who are at puberty, are obese, or have other increased risks. Short children who were born SGA may be at increased risk of dyslipidemia,14 and children are born SGA are at increased risk of hypertension.45,46 For these reasons, plasma lipid levels and blood pressure should be measured before the start of GH therapy.
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WHAT IS THE ROLE OF GH THERAPY IN THE TREATMENT OF SHORT CHILDREN WHO ARE BORN SGA? |
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TOPABSTRACTINTRODUCTIONHOW SHOULD SGA BE...HOW SHOULD THE CAUSES...HOW SHOULD CATCH-UP GROWTH...HOW SHOULD SHORT CHILDREN...WHAT IS THE ROLE...CONCLUSIONSREFERENCES |
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Parents may not consult a pediatrician for evaluation of short stature of their prepubertal child who is SGA and has failed to catch up until there is a large height deficit. Clinical trials have shown that the growth response to GH is better when children begin therapy in early childhood31,37 and that age at the initiation of therapy is a major determinant of growth response.37,41 Therefore, the age of the child must be considered when parents are educated about treatment objectives and efficacy. In addition, target height should be considered, although it should not be used to exclude any child who is SGA and would otherwise be treated for failure to catch up. Given the known influence of parental height, treatment goals may need to be modified. Optimized or revised SGA prediction models that include genetic factors such as parental height and potential new factors involved in the catch-up mechanism are needed.
Pediatricians should discuss all aspects of SGA with parents, including the need for psychological support. One study showed that infants who are SGA may be more vulnerable to adverse social conditions than infants who are AGA.47 Lack of appropriate cognitive stimulation was found to be more likely in the home environment of children who are born SGA than in that of children who are born AGA. Cognitive impairment in such children may result not only from IUGR but also from this less-than-optimal home environment for cognitive stimulation.
SGA is more than a "height" issue. In addition to having short stature, infants who are born SGA usually have less body fat than infants who are born AGA.48 At 7 years of age, short children who were born SGA remain not only shorter but also leaner than children who were born AGA.49 Serum concentrations of leptin, a protein produced by adipose tissue and involved in the regulation of appetite and body weight,50 are reduced in short children who were born SGA, and leptin levels may reflect the nutritional state of these children.51 Many children who were born SGA may not consume an adequate number of calories because of a lack of appetite. Ideally, pediatricians and parents should document the caloric intake of such children; in those who are being treated with GH, this will serve to monitor the effect of GH therapy on appetite.
Children who are born SGA are at increased risk of impaired neurologic development,52–55 school performance,56,57 and socialization.5–11,58 These potential sequelae should be discussed with parents. Behavior and social problems in children with idiopathic short stature or short stature as a result of GH deficiency improved after treatment with GH for 3 years, but there was no improvement in mean intelligence or achievement scores.59 To our knowledge, there are no such published studies of children who are SGA.
Metabolic syndrome—type 2 diabetes, hypertension, obesity, and hyperlipidemia—has been reported in adults who were born SGA.60 The risk is increased in those who were born SGA and are overweight. Later adverse outcomes, including the metabolic syndrome with all its diverse components, have been reported primarily in children who are SGA and experienced excessive weight gain during childhood. Regular monitoring of weight, height, and body mass index during adolescence is particularly important in these patients. It remains to be determined whether GH therapy in short children who were born SGA has any beneficial or deleterious effect on their risk of developing metabolic syndrome in adulthood.
Treatment Objectives
The initial objective of GH therapy is to accelerate prepubertal linear growth to achieve catch-up to a normal height in early childhood and maintain normal growth later in childhood. The ultimate objective is to normalize adult height. Parental height and birth length are the only variables that seem to be predictive of adult height in untreated children who are born SGA.61 In GH-treated short children who were born SGA and were followed to (near) adult height, GH therapy effectively increased adult height above predicted height, and patients achieved target height.62
GH Therapy for SGA
GH therapy is indicated for children who were born SGA and have persistent short stature (height below –2 SD); are at least 2 to 3 years of age; and are growing at an average or subnormal rate for age, provided that other causes for short stature such as growth inhibiting medication, chronic disease, endocrine disorders, emotional deprivation or syndromes (except of Silver Russell syndrome) have been ruled out.
Before GH therapy for a short child who was born SGA is considered, it is important to wait until the spontaneous catch-up phase is completed, which usually occurs by the time a child is 2 to 3 years of age. (Some children—eg, those born very prematurely—may have a longer period of spontaneous catch-up growth.) Children who begin GH therapy much later (9 or 10 years of age) may also benefit from treatment, although they experience a mean lower growth velocity than those who start treatment earlier. Although specific recommendations regarding an optimal treatment regimen must await additional investigation, published studies have shown that GH therapy is effective and safe for persistently short children who were born SGA and achieved insufficient catch-up growth.
A number of clinical trials have confirmed that GH effectively and safely induces catch-up growth in short prepubertal children who were born SGA, some of which are summarized below. Although the increment in adult height resulting from GH treatment is not yet precisely defined, most trials reported to date demonstrate stimulation of skeletal growth of sufficient duration and magnitude to recommend therapy.
In a study of children who were a mean age of 4.5 years and had severe short stature (
3 SD below the mean for chronologic age and gender) and a history of IUGR (birth weight <10th percentile), GH therapy induced sustained catch-up growth.63 All children received GH at a dose of 0.2 IU/kg/d (0.48 mg/kg/wk) for 3 years, although 1 of the 2 groups initially underwent a 1-year observation period, which confirmed that no clinically significant acceleration of height velocity occurred. After 3 years of treatment, mean height SDS for chronologic age had increased by 2.0 ± 0.7 in the 2 groups, and no clinical adverse events were related to treatment.
In the Nordic Multicentre Trial, short children who were born SGA, aged 2 to 8 years, achieved their target height SDS within 3 years of treatment with GH at a dose of 0.1 or 0.2 IU/kg/d (0.24 or 0.48 mg/kg/wk).41 Dose was a determinant of the growth response, with the group that received the 0.2 IU/kg dose achieving an attained height SDS of –0.90 after 3 years, compared with –1.29 for the group that received 0.1 IU/kg. Also, the younger the child at the start of treatment and the greater the family-corrected individual height deficit, the better the growth response. Treatment was well tolerated, and no GH-related adverse events were detected.
The results of 3 short-term French studies showed that the growth rate accelerated markedly, nearly doubling after 1 year of treatment, with GH doses up to 1.4 IU/kg/wk (0.48 mg/kg/wk), which is up to 3 times greater than the standard replacement doses used to treat children with GH deficiency (ie, 0.16–0.24 mg/kg/wk).64 Mean height increased by nearly 2.0 SDS over the 3-year treatment period, although, as in all GH trials, a progressive decrease in the effect on growth rate occurred over time. This treatment was well tolerated without significant adverse effects.
A review of data from the National Cooperative Growth Study showed that children who had IUGR-associated short stature and were treated with 0.30 mg/kg/wk GH for up to 4 years experienced a progressive increase in height SDS with each year of therapy.65 There was no control population. The height SDS at baseline for those with unclassified IUGR was –3.49, which improved to –1.32. Despite these encouraging results, no improvement in predicted adult heights was detected.
Five-year data from a Dutch study showed that long-term continuous GH therapy at a dose of either 3 IU/m2/d (0.24 mg/kg/wk) or 6 IU/m2/d (0.48 mg/kg/wk) in short children who were born SGA results in normalization of height and subsequent growth along the target height percentile.37 The 5-year increase in height SDS for chronologic age was 2.6 ± 0.9 for the 6-IU group and 2.2 ± 0.6 for the 3-IU group; these changes were significantly different from baseline values (P < .001) but not significantly different from each other. Also, this 5-year increase did not differ between those with GH deficiency and those without GH deficiency. No drug-related adverse events were reported.
A meta-analysis of 6-year growth responses from 4 European studies of short children who did not have GH deficiency and were born SGA determined that GH effectively normalized height during childhood and early puberty.30 Children were treated with GH continuously (33 µ g/kg/d [0.24 mg/kg/wk] or 67 µ g/kg/d [0.48 mg/kg/wk]) or discontinuously (initial treatment for 2–3 years at a dose of 33–100 µ g/kg/d [0.24–0.72 mg/kg/wk] followed by withdrawal for 1–2 years, and then either 1 or more additional treatment periods at the same dose or no additional treatment). After 6 years, height increased toward the norm by 1.9 ± 0.1 SD. In contrast, untreated controls experienced no catch-up, and their height increased toward the norm by <0.1 ± 0.1 SD. This finding suggests that the cumulative GH dose received and not the dosing regimen determines the growth response.15 Treatment with GH was well tolerated.
In July 2001, GH was approved by the US Food and Drug Administration for the long-term treatment of growth failure in children who are born SGA and do not achieve catch-up growth by 2 years of age, at dosages up to 0.48 mg/kg/wk.
GH Dosing for SGA
The dose of GH is the most important predictor of the growth response to therapy during the first year of treatment among short children who were born SGA.66 When a GH dose of 0.1 IU/kg/d (0.24 mg/kg/d) was used, the growth response of short children who were SGA matched that of children who had GH deficiency and were not SGA and were treated with a GH dose of 0.07 IU/kg/d.40 Currently available data suggest that the higher dosage—0.48 mg/kg/wk (0.2 IU/kg/d)—is efficacious and safe at initiation of therapy when rapid catch-up growth is desired. Doses <0.1 IU/kg/d (0.24 mg/kg/wk) may be effective in the long-term, although, according to the results of 2 studies, these low GH doses may be inadequate for some children who start therapy relatively late. Zucchini et al67 found that GH at a dose of 20 U/m2/wk (0.23 mg/kg/wk) for 36 to 84 months was not effective in 29 low birth weight children who had GH deficiency. In addition, Coutant et al68 found that an average dose of 0.4 U/kg/wk (0.13 mg/kg/wk) had a limited effect on adult height in 70 children who were SGA and had GH deficiency. In both these studies, GH was given at a dose less than or equal to the replacement dose for GH deficiency. In addition, treatment was started when the children’s average age was >10 years, which likely compromised the effect.
When catch-up growth has been achieved and during puberty, individual dose adjustments may be made within the 0.24 to 0.48 mg/kg/wk (0.1–0.2 IU/kg/d) range. Additional information is required before specific dose recommendations can be made for patients with "catch-down" (deceleration of growth rate) when goal height is achieved.
Although the goal of GH therapy is improved adult height, at present, too few studies using appropriate GH doses in younger children have been published that accurately determine the effect of GH therapy on final height. Nevertheless, data based on GH therapy over 6 years compose the basis for the recommendations of this consensus statement.
Monitoring During Therapy
The effect of GH on glucose metabolism in short children who were born SGA is of potential concern, and carbohydrate metabolic status should be reassessed during GH therapy. Fasting serum glucose and insulin levels should be measured annually. In children who experience excessive weight gain, develop acanthosis, belong to an ethnic group at risk, or have a strong family history of type 2 diabetes, glucose homeostasis should be monitored more frequently and intensely (oral glucose tolerance test with insulin measurements). It should be noted, however, that the effects of GH therapy on glucose metabolism are generally mild and transient. No adverse effects on serum glucose levels were found in 79 prepubertal children who were SGA and had short stature and were treated with GH continuously at a dose of either 0.24 or 0.48 mg/kg/wk (0.1 or 0.2 IU/kg/d) for 6 years.44 Notably, in a study of the relationship between insulin resistance and plasma concentrations of potential inhibitors of the insulin receptor substrate system, plasma levels of GH and IGF-I were not elevated in obese people who had impaired glucose tolerance and were at an early stage of diabetes development.69 This finding suggests that elevation of GH or IGF-I is not a primary metabolic abnormality that leads to insulin resistance.
Fasting serum lipids and blood pressure should be monitored periodically for purposes of long-term surveillance during GH therapy. It should be noted that neither serum lipids nor blood pressure increased from baseline during 4 and 6 years, respectively, of GH therapy for short stature among 79 children who were born SGA.46
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CONCLUSIONS |
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Maternal, placental, and fetal causes of SGA should be sought, although the cause is often not clear. Such studies may reveal important information concerning heritability in genetic disorders or the need to assess patients for associated medical conditions.
Most children who are SGA experience catch-up growth and achieve a height >2 SD below the mean, and the catch-up process is complete at 2 to 3 years of age in most infants. A short child who was born SGA and is older than 3 years and shows no evidence of continuing catch-up growth is not likely to catch up later on and should be referred to a pediatrician who has expertise in endocrinology.
A standard evaluation for short stature should be performed, although bone age is not a reliable predictor of height potential in SGA. SGA does not exclude GH deficiency, and GH assessment should be performed if there is clinical suspicion or biochemical evidence of GH deficiency. All aspects of SGA and not just increased height should be addressed with parents.
The objectives of GH therapy are catch-up growth in early childhood, maintenance of normal growth in childhood, and achievement of normal adult height. Before treatment, fasting glucose, insulin, and lipid levels; IGF-I and IGFBP-3 levels; and blood pressure should be measured. GH therapy is effective and safe in short children who were born SGA (–2 SD) and should be considered in those who are older than 2 to 3 years and have persistent short stature (–2 SD). Higher GH doses (0.48 mg/kg/wk [0.2 IU/kg/d]) are generally more effective to induce short-term catch-up growth than doses in the standard replacement range. Adult height data are required, however, to determine whether the higher GH dose is also more efficacious than a lower dose of 0.1 IU/kg/d (0.24 mg/kg/d) concerning adult height attainment. Children should be monitored for changes in glucose homeostasis, lipids, and blood pressure during and after therapy.
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ACKNOWLEDGMENTS |
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The authors gratefully acknowledge the contribution of David Dunger, MD, to the sections of this article relating to glucose metabolism.
International SGA Advisory Board: Kerstin Albertsson-Wikland, MD, PhD, Göteborg University, International Pediatric Growth Research Center, Göteborg, Sweden; Antonio Carrascosa, MD, PhD, Autonomous University, Hospital Vall d’Hebron, Barcelona, Spain; Steven D. Chernausek, MD, Children’s Hospital Medical Center, University of Cincinnati School of Medicine, Cincinnati, Ohio; Paul Czernichow, MD, University Saint-Louis Lariboisière, Department of Pediatric Endocrinology and Diabetes, Hôpital Robert Debré, Paris, France; Francis de Zegher, MD, Department of Pediatrics, Catholic University of Leuven, University Hospital Gasthuisberg Leuven, Leuven, Belgium; David Dunger, MD, Department of Pediatrics, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom; Wayne Cutfield, MD, University of Auckland, Starship Children’s Hospital, Auckland, New Zealand; Anita C.S. Hokken-Koelega, MD, PhD, Sophia Children’s Hospital, Erasmus University of Rotterdam, Rotterdam, the Netherlands; Ieuan Hughes, MD, Department of Pediatrics, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom; Peter A. Lee, MD, PhD, Pennsylvania State University College of Medicine, Hershey Medical Center, Hershey, Pennsylvania; Robert Rapaport, MD, Mount Sinai School of Medicine, Division of Pediatric Endocrinology and Diabetes, Mount Sinai Diabetes Center, New York, New York; Luciano Tatò, MD, PhD, Department of Pediatrics, Obstetrics, Biology and Genetics, University of Verona, Department of Pediatrics, Polyclinic G.B. Rossi, Verona, Italy; and Torsten Tuvemo, MD, Department of Women’s and Children’s Health, Uppsala University Children’s Hospital, Uppsala University, Uppsala, Sweden.
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FOOTNOTES |
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REFERENCES |
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, angiotensin II, growth hormone, and IGF-I are not elevated in insulin-resistant obese individuals with impaired glucose tolerance.
Diabetes Care.2001; 24
:328
–334This article has been cited by other articles:
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  N. Teeninga, M. F. Schreuder, A. Bokenkamp, H. A. D.-v. d. Waal, and J. A.E. v. Wijk Influence of low birth weight on minimal change nephrotic syndrome in children, including a meta-analysis Nephrol. Dial. Transplant., May 1, 2008; 23(5): 1615 - 1620. [Abstract] [Full Text] [PDF]
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 A. Carrascosa, L. Audi, M. Fernandez-Cancio, C. Esteban, P. Andaluz, E. Vilaro, M. Clemente, D. Yeste, M. A. Albisu, and M. Gussinye The Exon 3-Deleted/Full-Length Growth Hormone Receptor Polymorphism Did Not Influence Growth Response to Growth Hormone Therapy over Two Years in Prepubertal Short Children Born at Term with Adequate Weight and Length for Gestational Age J. Clin. Endocrinol. Metab., March 1, 2008; 93(3): 764 - 770. [Abstract] [Full Text] [PDF]
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 C. Giorlandino and P. Cignini Iron supplementation in non-anaemic women did not improve pregnancy outcomes and may be harmful to both mother and baby Evid. Based Med., February 1, 2008; 13(1): 15 - 15. [Full Text] [PDF]
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 M. G. Oliveira, R. C. Silveira, and R. S. Procianoy Growth of Very Low Birth Weight Infants at 12 Months Corrected Age in Southern Brazil J Trop Pediatr, February 1, 2008; 54(1): 36 - 42. [Abstract] [Full Text] [PDF]
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A. Carrascosa, L. Audi, C. Esteban, M. Fernandez-Cancio, P. Andaluz, M. Gussinye, M. Clemente, D. Yeste, and M. A. Albisu Growth Hormone (GH) Dose, But Not Exon 3-Deleted/Full-Length GH Receptor Polymorphism Genotypes, Influences Growth Response to Two-Year GH Therapy in Short Small-for-Gestational-Age Children J. Clin. Endocrinol. Metab., January 1, 2008; 93(1): 147 - 153. [Abstract] [Full Text] [PDF]
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S. Suzuki, Y. Makita, T. Mukai, K. Matsuo, O. Ueda, and K. Fujieda Molecular Basis of Neonatal Diabetes in Japanese Patients J. Clin. Endocrinol. Metab., October 1, 2007; 92(10): 3979 - 3985. [Abstract] [Full Text] [PDF]
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