Diagnosis of growth hormone (GH) deficiency and the use of GH in children with growth disorders

The diagnostic work up of growth failure in secondary health care; an evaluation of consensus guidelines

Background

As abnormal growth might be the first manifestation of undetected diseases, it is important to have accurate referral criteria and a proper diagnostic work-up. In the present paper we evaluate the diagnostic work-up in secondary health care according to existing consensus guidelines and study the frequency of underlying medical disorders.

Methods

Data on growth and additional diagnostic procedures were collected from medical records of new patients referred for short stature to the outpatient clinics of the general paediatric departments of two hospitals (Erasmus MC – Sophia Children's Hospital, Rotterdam and Spaarne Hospital, Haarlem) between January 1998 and December 2002. As the Dutch Consensus Guideline (DCG) is the only guideline addressing referral criteria as well as diagnostic work-up, the analyses were based on its seven auxological referral criteria to determine the characteristics of children who are incorrectly referred and the adequacy of workup of those who are referred.

Results

Twenty four percent of children older than 3 years were inappropriately referred (NCR). Of the correctly referred children 74–88% were short corrected for parental height, 40–61% had a height SDS <-2.5 and 21% showed height deflection (Δ HSDS < -0.25/yr or Δ HSDS < -1). In none of the children a complete detailed routine diagnostic work up was performed and in more than 30% no routine laboratory examination was done at all. Pathologic causes of short stature were found in 27 children (5%).

Conclusion

Existing guidelines for workup of children with suspected growth failure are poorly implemented. Although poorly implemented the DCG detects at least 5% pathologic causes of growth failure in children referred for short stature. New guidelines for referral are required with a better sensitivity and specificity, wherein distance to target height should get more attention. The general diagnostic work up for short stature should include testing for celiac disease in all children and for Turner syndrome in girls.

Administration of arginine plus growth hormone releasing hormone to evaluate growth hormone (GH) secretory status in children with GH deficiency

BACKGROUND

Diagnosis of growth hormone deficiency (GHD) in childhood is usually based on growth hormone (GH) response to at least two provocative stimuli. The aim of this study was to determine whether sequential administration of arginine (Arg) plus GH releasing hormone (GHRH) could be a useful tool in evaluating GHD in children.

METHODS

Thirty patients with short stature (mean age 9.0 years) with decreased growth rate were tested for GHD with Arg and the insulin tolerance test (ITT). Patients with confirmed GHD (peak GH <8 ng/ml) were subsequently tested with Arg + GHRH.

RESULTS

Maximum GH stimulation for Arg and ITT was 6.3 (1.0-7.8) and 6.7 (0.5-7.7) ng/ml, respectively. Peak GH for the Arg + GHRH test was 36.3 (4.3-84.5) ng/ml and significantly different from the other provocative tests. Peak GH values for the three tests were not significantly correlated between tests or with clinical parameters. There were no significant differences in Arg + GHRH results between children with or without abnormal hypothalamic-pituitary MRI scans.

CONCLUSION

Arg + GHRH gave higher GH levels than insulin or Arg alone. Because of the different causes of childhood GHD (hypothalamic and/or pituitary dysfunction), the Arg + GHRH test is unsuitable .for evaluating GHD and deciding whether GH replacement therapy is indicated.

Plasma insulin-like growth factors (IGFs), IGF-Binding proteins (IGFBPs), acid-labile subunit (ALS) and IGFBP-3 proteolysis in individuals with clinical characteristics of Sotos syndrome

OBJECTIVE

Sotos syndrome is an overgrowth syndrome of poorly understood aetiology. We investigated whether this syndrome is related to alterations in plasma insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), acid-labile subunit (ALS) and serum IGFBP-3 proteolysis.

DESIGN

Based on clinical criteria, 32 patients with clinical characteristics of Sotos syndrome (median age 8.4 years, range 1.8-48.4) were categorised into three groups: typical (n = 10, group 1), dubious (n = 12, group 2) and atypical (n = 10, group 3). Blood samples were obtained from 29 patients.

MEASUREMENTS

Plasma IGF-I, IGF-II, E-II (pro-IGF-II and E-domain fragments), IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6 and ALS were measured by specific radioimmunoassays (RIAs). Except for E-II immunoreactivity, the concentrations were compared with those of age references, and expressed as standard deviation scores (SDS). IGFBP-3 proteolysis was assessed by incubation of serum with [125I]-IGFBP-3, followed by gel electrophoresis and was then compared with that in normal serum and third trimester pregnancy serum.

RESULTS

Patients in group 1 showed significantly reduced plasma levels of IGF-II (median -0.9 SDS; p = 0.01), IGFBP-4 (-0.5 SDS; p = 0.02) and IGFBP-3 (-1.0 SDS; p = 0.01). Mean IGFBP-3 proteolysis was higher than in normal standard serum (61% vs 37%; p < 0.01) but lower than in third trimester pregnancy serum (94%; p < 0.01). Plasma IGF-I showed a tendency towards low values (median -0.9 SDS; p = 0.09), IGFBP-6 and ALS a tendency towards elevated levels (median values +0.8 SDS; p = 0.07 and +2.3 SDS; p = 0.09), and IGFBP-2 was normal. The mean value of E-II immunoreactivity was 8.7 nmol/l, similar to that in pooled normal plasma (8.6 nmol/l). Plasma and serum parameters in groups 2 and 3 were similar to reference values with the exception of plasma IGFBP-3 (in groups 2 and 3 median < or = -1.1 SDS; p < or = 0.02) and ALS (in group 3 median +1.3 SDS; p < 0.01).

CONCLUSIONS

Patients with typical Sotos syndrome show low plasma IGF-II, IGFBP-3, IGFBP-4, and increased proteolysis of IGFBP-3 in serum. The extent to which these findings are associated with the pathophysiology of Sotos syndrome remains uncertain.

European audit of current practice in diagnosis and treatment of childhood growth hormone deficiency

BACKGROUND

The present survey among members of the ESPE on current practice in diagnosis and treatment of growth hormone (GH) deficiency (GHD) is of great clinical relevance and importance in the light of the recently published guidelines for diagnosis and treatment of GHD by the Growth Hormone Research Society. We have found much conformity but also numerous discrepancies between the recommendations of the Growth Hormone Research Society and the current practice in Europe.

RESULTS

We found that 80% of the pediatric endocrinologists included insulin-like growth factor I (IGF-I) in their initial evaluation of a short child suspected of having GHD, whereas only 22% used GH provocative testing alone in the initial evaluation of a short child. Sixty-eight percent confirmed the diagnosis of GHD using two separate provocative tests. In the present survey cutoff values for GH provocative testing clustered around two values; 10 ng/ml and 20 mU/l. Interestingly, these two values, differing by a factor of 2, were also the most prevalent cutoff values among those who reported their assay to be calibrated against the WHO International Reference Preparation 80/505 where the conversion factor between milligrams and milliunits is 2.6. This suggests that the selection of cutoff values is based on tradition rather than on specific GH assay characteristics. In addition, only 63% of the respondents actually knew what GH assay they were using, and only 57% knew how their GH assay was calibrated. Dosing of GH at the start of treatment was reported according to body surface by 39%, whereas 59% were dosing according to body weight. GH dose adjustment was primarily based on growth response and height during auxological assessment every 3-4 months (height velocity, change in height velocity or change in height standard deviation scores) as indicated by almost 70% of the respondents. However, dose adjustment according to body surface (38%) and body weight (44%) was also quite common. Sixty-five percent measures IGF-I regularly (at least once a year) during GH therapy in children, and to our surprise 17% reported that they adjust the GH dose according to the IGF-I levels.

SUMMARY

In summary, we have found large heterogeneity in the current practice of diagnosis and treatment of childhood GHD among European pediatric endocrinologists. Especially standardizations of GH assays and cutoff values are urgently required to ensure a uniform and correct diagnosis and therapy of GHD in the future.

Re-assessment of growth hormone secretion in young adult patients with childhood-onset growth hormone deficiency

OBJECTIVE

Patients with childhood-onset GH deficiency (coGHD) need retesting in late adolescence or young adulthood to verify whether they need to continue GH treatment. For this purpose the Growth Hormone Research Society (GRS) recommends the insulin tolerance test (ITT), or as an alternative the arginine + growth hormone releasing hormone test (ARG + GHRH test) as a diagnostic tool in adolescents and adults. However, there are no standardized cut-off levels based on normal GH secretion for determining GHD vs. GH sufficiency in young adults for the ITT, the ARG + GHRH test or the pyridostigmine + GHRH (PD + GHRH) test, a further new GH stimulation test.

PATIENTS AND MEASUREMENTS

We studied 43 patients (28 with organic coGHD, 15 with idiopathic coGHD; 30 males, 13 females; aged 20.4 years, range 16.2-25.4; body mass index 23.5, range 16.3-35.8) using the ARG [0.5 g/kg intravenously (i.v.)] + GHRH (1 micro g/kg i.v.) test, the PD (120 mg orally) + GHRH (1 micro g/kg i.v.) test and the ITT (0.1 IU/kg i.v.) and compared these data with the results of 40 healthy age- and weight-matched volunteers.

RESULTS

The GH response in patients was significantly lower than in healthy controls: ARG + GHRH test, 0.8 micro g/l (interquartile range 0.3-2.6) vs. 51.8 micro g/l (32.6-71.2) in controls (P < 0.0001); PD + GHRH test, 0.9 micro g/l (0.3-1.9) vs. 40.4 micro g/l (27.1-54.4) in controls (P < 0.0001); ITT, 0.1 micro g/l (0.0-0.8) vs. 20.3 micro g/l (14.7-31.7) in controls (P < 0.0001). In the ARG + GHRH test we found a diagnostic sensitivity of 100% and a specificity of 97.5% for a cut-off range from 15.1 to 20.3 micro g/l, in the PD + GHRH test a sensitivity of 100% and a specificity of 97% (cut-off range 9.1-13.1 micro g/l) and in the ITT a sensitivity and specificity of 100% each within a cut-off range from 2.7 to 8.8 micro g/l.

CONCLUSION

There were no marked differences in sensitivity and specificity in young adults among ARG + GHRH test, PD + GHRH test and the ITT in assessing GH secretion. Because of the lack of side-effects, the ARG + GHRH test is the recommended method for re-evaluation of coGHD in young adults when pituitary GHD is suspected. Furthermore, in adult patient groups where organic pituitary coGHD is common, the ITT may be completely replaced by the ARG + GHRH test. Because of the predominance of hypothalamic GHD in childhood, the ITT is commonly performed for the re-evaluation of patients with childhood-onset GHD because of its mechanism of GH stimulation. The present results confirm the high discriminatory capability of the ITT in young adults.

Long-Term GH therapy: epidemiology and auxologic outcome

OBJECTIVES

Epidemiologic and auxologic characteristics of patients treated with GH during childhood and adolescence and entered in a national registry in Catalonia were studied between 1988 and 1997. At the end of 1997, prevalence was 53.2 treatments/100,000 inhabitants aged 0-14 years. Maximum annual incidence rates were observed in 1990 and 1991 (34.0-35.6 cases/100,000 inhabitants aged 0-14 years).

STUDY DESIGN

Analysis of treatments terminated in 1993 (n = 548) revealed, for the three principal reasons for cessation of treatment ('near-final height', 'adequate height but further growth potential', and 'poor growth response'), that males began and ended treatment at older ages with a better auxologic situation in SDS than girls at the beginning and end of therapy in the first two subgroups, with a similar duration of therapy. Severe GH deficiency (GHD) [both multiple pituitary hormone deficiency (MPHD) and the most severe isolated GHD (IGHD-A)] was more frequent in the group ending treatment at 'near-final height', whereas cessation of therapy because of 'poor growth response' was more frequent in the group with 'other causes of short stature' and no demonstrable GHD by routine tests. In the near-final height group, after excluding Turner's syndrome, MPHD and GHD cases secondary to brain tumors and GH deficiencies associated with malformative syndromes, positive linear correlations were observed between HSDS at the end of treatment and HSDS at the beginning, predicted adult height SDS (PAHSDS) and target height SDS (THSDS). Multiple regression analysis showed that in this group of patients, 41.4% of the variability in HSDS increment can be explained by the equation: HSDS increment = -0.33 + 0.29 THSDS - 0.68 HSDS at the beginning of treatment.

RESULTS

The outcome showed a reasonable use of GH, since good-response cases generally continued treatment until final height whereas therapy was suspended in doubtful cases.

Favorable final height outcome in girls with Ullrich-Turner syndrome treated with low-dose growth hormone together with oxandrolone despite starting treatment after 10 years of age

The objective of this study was to find out whether moderate doses of growth hormone (GH) in combination with oxandrolone (Ox) and late initiation of puberty could improve adult height even in relatively old patients with Ullrich-Turner syndrome (UTS). Ninety-one patients with UTS were randomly assigned to receive either GH alone (Saizen, Ares-Serono, Geneva) 18 IU/m2/week (0.2 mg/kg/week) by daily s.c. injections (group GH) or a combination of GH and Ox 0.1 mg/kg/day p.o. (group GH + Ox). Prior to treatment mean age was 10.2 years (GH) and 10.5 years (GH + Ox), mean projected adult height (PAH) was 146.4 cm (GH) and 146.7 cm (GH + Ox). During year 2 the GH dose was increased in the GH group to 24 and later to 28 IU/m2/week (0.27 mg and later 0.31 mg/kg/week). In group GH + Ox, the Ox dose was reduced to 0.05 mg/kg/day after the first 12 months of therapy, and during the last treatment years the GH dose was raised to 24-28 IU/m2/week (0.27-0.31 mg/kg/week) due to declining growth promotion. Some of the patients of group GH were later given Ox in addition to GH because of waning growth velocity, whereas some of the patients of group GH + Ox were taken off Ox due to virilizing side-effects of the high Ox dose, thus making up a third group of patients: group GH + transient Ox. Puberty was induced at a mean age of 14.9 years. In group GH + Ox, cumulative growth during 5 years of therapy was twice the growth anticipated from standards of untreated patients with UTS. Forty-seven patients are now near or at final height: in group GH (n = 7), mean final height was 151.7 cm (PAH 148.1 cm, gain 3.6 cm); in group GH + Ox (n = 15), 155.1 cm (PAH 147.2 cm, gain 7.9 cm); and in group GH + transient Ox (n = 25), 152.8 cm (PAH 146.4 cm, gain 6.4 cm). These results should be regarded as an underestimate of true final height since some the patients are still growing. Moderate doses of GH plus Ox and late induction of puberty definitely improved final height even in patients with UTS treated relatively late.