Central precocious puberty (CPP) is the development of sex pubertal characteristics as a consequence of premature activation of the hypothalamic-pituitary-gonadal axis (HPG axis) before the age of eight years in girls and nine years in boys. Pathogenesis of CPP include early activation of the release of gonadotropin-releasing hormone (GnRH), leading to increased gonadal steroid and gonadotropin secretion. The prevalence of CPP is estimated to be around  1 : 5,000 to 1 : 10,000. Central precocious puberty is more often found in girls than boys (ratio > 20 : 1).1,2 Approximately 95% of CPP occurs in girls, and 90% of CPP in girls is idiopathic. Children with CPP may experience various growth, development, and psycho-social problems.3  The aim of CPP management includes hormonal suppression, regression or cessation of the development of pubertal characteristics, preventing early menarche short stature in adulthood. Patients with CPP is at risk of having short stature in adulthood due to imbalance of skeletal maturation associated with growth acceleration during early epiphyseal fusion, which prevents growth.4-7

Gonadotropin-releasing hormone analogue (GnRHa) has become the standard care for children with CPP for more than 20 years since 1989 and is now used to inhibit pubertal progression and increase height prospect. The GnRHa preparations are available in forms of depots, such as depot leuprolide (DL) which is one treatment option for CPP available for intramuscular (IM) or  subcutaneous (SC) injections.4,8,9 It has been reported that GnRHa is safe, effective and has reversible effects on the HPG axis function. Several previous reports had shown improvement in  final height with GnRHa therapy.8

Leuprolide acetate (LA) dose varies from one country to another, ranging from 3.75 to 15 mg with 4 weeks interval or more frequent. In the United States, the recommended initial dose is 0.3 mg/kg ranging from 7.5-15 mg. In Asia and Europe, the standard dose is 3.75 mg, while the minimum suppression dose is 0.03 mg/kg, about 1/10 of the recommended dose in the US. The initial dose in Europe and Asia tends to be lower because researchers from Japan and France have reported the achieved long-term pubertal suppression in CPP with the dose of 3.75 mg every four weeks. Badaru (2006) studied the effectivity of low dose LA 3.75 mg/month and 1.25 mg/3 months compared to 7.5 mg/month using a monthly serial comparison. 7,9-11

The objective of this study is to compare the effect of LA treatment on luteinizing hormone (LH)  secretion in CPP patients when given for one month and three months.

A systematic literature research was conducted to identify studies which fitted the criteria, written in English and without restricting the publication year. Sources used in this research were MEDLINE (Pubmed), The Cochrane Library, EBSCO, and Proquest. The investigators were contacted to obtain further study data information.  

Clinical trial reports, reviews, meta-analyses, guidelines, and health technology assessment which met the inclusion criteria were included in this study. Handsearch was done for conference abstracts associated with this meta-analysis. Clinical trial registries, including WHO international registry platform and clinicaltrials.gov were searched for ongoing clinical trials.

Three investigators (RDA, ABP, KH) independently reviewed all potentially relevant articles. The investigators evaluated the title and abstract of the studies, and then the complete article. Disagreement among the three investigators was discussed to reach a consensus. Study selection flow was conducted based on modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIMA). 12

Inclusion criteria were published and unpublished randomized controlled trials (RCTs), girls and boys below eight and nine years old, respectively, who presented signs of secondary pubertal signs (pubertal status ≥ Tanner 2), laboratory results showed an increase in basal LH, or  LH more than 5 IU/L after GnRHa stimulation test. Subjects in the studies had to be treated with LA for at least 12 months, given monthly or every three months to evaluate suppression effect of gonadotropin secretion in the previously randomized CPP patients. LA dose was the restriction criterion in this study.

Three investigators (RDA, ABP, KH) performed data extraction independently and discussed to reach a consensus on any disagreements. Data extraction included study type, research subjects, intervention, as well as the primary and secondary outcomes.  

The investigators independently evaluated every study regarding bias risks, which included assessment of randomization, allocation concealment, blinding, outcome assessment adequacy, selective reporting, and other sources of biases.  

Primary (LH supression) and secondary outcomes (growth velocity) were evaluated based on the mean difference, with Confident Interval (CI) 95%. When data analysis using intention-to-treat was not possible, data analysis was performed per protocol or using available data.  

The authors of the analysed studies were contacted for missing data. This systematic review presented the event of drop-out, loss to follow-up, withdrawals and critically evaluated the event of these missing data. Bias assessment was not reported in the form of funnel plot because only two studies met the outcome criteria. Language and location were reporting biases in this meta-analysis because only journals in English were included and only a few databases were included.

The studies analyzed were homogenous, intrastudies variability used was based on opportunities or chance. Therefore, fixed-effect model analysis was used, where only studies with a low degree of heterogeneity were analyzed.13 In this meta-analysis, subgroup analysis could not be performed because of the data limitations. Results analysis was performed by comparing fixed-effect and random effect models. Results from the two statistic models were not different; therefore studies with fewer subjects did not affect the results.

The meta-analysis from two studies which compared the effect of LA 7.5 mg/month, 11.25 mg/3 months, and 22.5 mg/3 months on LH suppression showed statistically significant results. The administration of LA 7.5 mg/month resulted in higher LH suppression compared to 11.25 mg/3 months and 22.5 mg/3 months, each with 0.59 (CI 95% 0.38; 0.80) IU/L and 0.15 (CI 95% 0.02; 0.27) IU/L after one year of follow up.  On the other hand, LA dose of 22.5 mg/3 months resulted in LH suppression higher than 11.25 mg/3 months; -0,45 (CI 95% -0,65; -0,25) IU/L. This result is in accordance with Fuld (2011) and Mericq (2009) who observed that high and monthly dose of LA for CPP might be needed in some conditions, and adequate dosage is important for an optimal outcome. 14,15 Fuld obtained no significant difference in LH suppression between 7.5 mg/month compared to 22.5 mg/3 months. Since LA injections every three months are preferable compared to monthly injections, the former are recommended for routine use, even though monthly injections are approved by Food and Drug Administration (FDA) in the USA for CPP treatment.

Theoretically, monthly injections with lower total dose compared to three-months injections may result in better LH suppression and clinical outcome. A study comparing monthly and three-months LA injections showed that continuous monthly injections were not preferable nor recommended. There are two approaches for routine LA injections per three months: every subject were given LA 22.5 mg/3 months, almost equal to the total dose of monthly injections, or starting from 11.25mg/3 months which was effective in most cases and can be increased if hormonal criteria were met or the patient’s symptoms were clinically persistent. 15

In this meta-analysis, LA 7.5 mg compared to 11.25 mg/3 months and 22.5 mg/3 months on growth velocity after one year of follow up was not statistically significantly different. This result is consistent with a study by Fuld (2011) which showed indifference of growth velocity in all groups, and in accordance with regression in normal pre-pubertal subjects during treatment. Fuld, et al followed the subjects for two years, yet no significant difference was found in terms of declining growth velocity during the second year of treatment. Growth velocity in boys and girls were equal (5.4 cm per year in the first year).15,16

In Fuld’s study (2011), LA treatment every three months showed a decrease in LH stimulation and estradiol concentration around ten times from the baseline and remained for two years. Bone age (BA) and growth velocity (GV) development were both suppressed for two years, either with monthly or every three months preparations. Three subjects in Fuld’s study showed LH level  >6 IU/L during therapy; one from each group. A girl aged two years with hypothalamus hamartoma in the group receiving 22.5 mg/3 months showed persistent increase in LH level 7-8 IU/L during 36 weeks of follow up. Then, the treatment was replaced with histrelin implant which produced higher suppression rates. A girl received monthly LA injections showed a progressively increased LH level up to 12 IU/L in 24 weeks accompanied by increased injection reaction, which improved after the regiment was changed to daily leuprolide. 15

In a study by Mericq (2009), GnRH stimulating peak LH  <2 IU/L, which was the main effect criteria, was observed in 80% case with treatment dose of 7.5 mg/month, in 75% with 11.25 mg/3 months, and 100% with 22.5 mg/3 months within six months of treatment. After 12 months, 100% patients had their LH level suppressed until <2 IU/L. This result showed that injections given every three months is preferable for children with CPP. Furthermore, LH suppression is achieved faster in dose 22.5 mg/3 months compared to dose 11.25 mg/3 months;  therefore adequate dose is important to achieve optimal effects. Further researches with longer duration of follow up for final height is needed, as well as for patients who weigh more than 30 kg Theoretically, LA dose of 22.5 mg/3 months is equal to 7.5 mg/month, while 11.25 mg/3 months is equal to a smaller monthly dose.

On study enrollment, the girls were in  Tanner stage 2 (n=3), Tanner stage 3 (n=3), Tanner stage 4 (n=7), and Tanner stage 5 (n=1). None of them had menarche when LA treatment started.  Breast Tanner stage did not change in seven of 14 girls, four of 14 girls had regression and breast stage progression was observed in three girls. One of the girls also experienced increased ovarium volume. Two girls were included in the group receiving LA 11.25 mg/3 months, which was the lowest dose given per month, and one girl in group receiving 7.5 mg/month. None of the three girls received LA dose of 22.5 mg/3 months.14,17

Bone age was delayed in all groups and there was no significant difference between the groups, although the duration of follow up (12 months) was considered short to evaluate bone age maturation rate. This result indicated that the dose given every three months might be too low. This study also showed that the increasing adult height was predictive in all groups, even though the duration of follow up was too short to be certain. 14 Other studies showed that patients with lower LH level have a higher adult final height prediction. Higher estradiol suppression can lead to slower bone maturation, slower pubertal progression and higher increase in final body height. While some studies confirm this theory, further researches are needed to see the long-term outcomes. Rapid changes in bone maturation associated with CPP can decrease adult height due to premature fusion of the epiphyseal growth plates.18,19,20

 It is important to determine any clinical benefits from higher LH suppression. The cost-benefit ratio is also important to analyze higher and more expensive doses toward growth velocity. Long-term data on final body height is necessary to make such analysis.14 Due to its high cost, treatment with GnRHa must be carefully considered. Adequate suppression must be obtained to achieve optimal results. Treatment must be given individually. Age on presentation, as well as the rate of pubertal acceleration and growth, should be taken into consideration. Girls whose height potential does not decrease might not need GnRHa treatment. If the pubertal growth spurt has already occurred and the BA is already mature, treatment might not be of much use, unless given for psychosocial reasons, such as to prevent early menstruation .9,21-23

This study concluded that LA injections every three months are a satisfying choice for treatment in children with CPP to avoid monthly injections. LH suppression occurred faster when given LA with the dose 22.5 mg/3 months compared to dose 11.25 mg/3 months; therefore, adequate dose important to achieve optimal outcomes.  Further studies are needed in patients with body weight more than 30 kg and with longer therapy duration with final body height analysis.14,24

Fuld’s study had a relatively larger sample size (n=54), but the value was small, while  Mericq’s study provided greater value although only involving a small sample (n=14). These results occured because studies with small standard deviation (SD) have a relatively greater value, while studies with big SD have a relatively small value. This is appropriate if SD variation among studies reflect differences in results measurement realibilities, but it might not be appropriate if difference in SD reflect significant difference within results variability in the study population.25

The weakness of this meta-analysis is the limited total sample size in the RCTs and follow up was done for only one year. Moreover, the two RCTs included in this study were not free of bias because concealment and blinding were not conducted.

1. Emre M, Bilir P, Köse K, Akçora D. The effect of gonadotropin-releasing hormone analog treatment ( leuprolide ) on body fat distribution in idiopathic central precocious puberty. J Pediatr. 2011;53:27–33.
2. Mul D, Oostdijk W, Drop SLS. Early puberty in girls. Best Pract Res ClinEndocrinolMetab. 2002;16:153–63.
3. Kim H. Clinical application of gonadotropin-releasing hormone analogs in children and adolescents. J Pediatr. 2010;53:294–9.
4. Lee PA, Neely EK, Fuqua J, Yang D, Larsen LM, Mattia-Goldberg C, et al. Efficacy ofleuprolide acetate 1-month depot for central precocious puberty (CPP): growth outcomes during a prospective, longitudinal study. Int J Pediatr Endocrinol. 2011;2011:1-9.
5. Neely EK, Lee PA, Bloch CA, Larsen L, Yang D, Mattia-Goldberg C, et al. Leuprolide acetate 1-month depot for central precocious puberty: hormonal suppression and recovery. Int J PediatrEndocrinol. 2010;1155:1-9.
6. Ben-haroush A, Goldberg-stern H, Phillip M, Vries L De. GnRH agonist treatment in girls with precocious puberty does not compromise post-pubertal uterine size. Hum Reprod. 2007;22:895–900.
7. Ohyama K, Tanaka T, Tachibana K, Niimi H, Fujieda K, Matsuo N, et al. Timing for discontinuation of treatment with a long-acting gonadotropin-releasing hormone analog in girls with central precocious puberty. TAP-144SR CPP Study Group. Endocrinol J. 1998;45:351–6.
8. Bajpai A, Menon PS. Precocious puberty. Dalam: Desai MP, Menon PSN, Bhatia V, editors. Pediatric Endocrine Disorders. 3rd ed. Hyderabad: Universities Press; 2014:144-7.
9. Batubara JRL. Gonadotropin-releasing hormone agonist as a treatment of choice for central precocious puberty. Med J Indones. 2010;19:287–92.
10. Cohen D, Janfaza M, Klein KO. Importance of leuprolide acetate variable dosing for precocious puberty: a range of acceptable suppression. J Pediatr Endocrinol Metab. 2009;22:629–34.
11. Badaru A, Wilson DM, Bachrach LK, Fechner P, Gandrud LM, Durham E, et al. Sequential comparisons of one-month and three-month depot leuprolide regimens in central precocious puberty. J Clin Endocrinol Metab. 2006;91:1862–7.
12. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: Explanation and elaboration. Ann Intern Med. 2009;151:1-28.
13. Deeks JJ, Higgins JP, Altman DG. Analysing data and undertaking meta-analyses. Dalam: Higgins JP, Green S, editors. Cochrane handbook for systematic reviews of interventions. Wiley-Blackwell. 2008:276-83.
14. Mericq V, Lammoglia JJ, Unanue N, Villaroel C, Hernández MI, Ávila A, et al. Comparison of three doses of leuprolide acetate in the treatment of central precocious puberty: Preliminary results. Clin Endocrinol. 2009;71:686–90.
15. Fuld K, Chi C, Neely EK. A randomized trial of 1- and 3-month depot leuprolide doses in the treatment of central precocious puberty. J Pediatr. 2011;159:982-7.e1.
16. Brown JJ, Warne GL. Growth in precocious puberty. Indian J Pediatr. 2006;73:81-8.
17. Lee PA, Klein K, Mauras N, Neely KE, Bloch CA, Larsen L, et al. Efficacy and safety of leuprolide acetate 3-month depot 11.25 milligrams or 30 milligrams for the treatment of central precocious puberty. J Clin Endocrinol Metab. 2012;97:1572–80.
18. Lee PA, Klein K, Mauras N, Lev-Vaisler T, Bacher P. 36-Month treatment experience of two doses of leuprolide acetate 3-month depot for children with central precocious puberty. J Clin Endocrinol Metab. 2014;99:3153-9.
19. Dimartino-nardi J, Wu R, Fishman K, Saenger P. The Effect of long-acting analog of luteinizing hormone-releasing hormone on growth hormone secretory dynamics in children with precocious puberty*. J ClinEndocrinolMetab. 1991;73:902–6.
20. Pasquino AM, Pucarelli I, Accardo F,Demiraj V, Segni M. Long-Term observation of 87 girls with idiopathic central precocious puberty treated with Gonadotropin-Releasing Hormone analogs: Impact on adult height, Body Mass Index, Bone Mineral Content, and Reproductive Function. J Clin Endocrinol Metab. 2015;93:190-5.
21. Acharya SV, Gopal RA, George J, Bandgar TR, Menon PS, Shah NS. Utility of single luteinizing hormone determination 3 h after depot leuprolide in monitoring therapy of gonadotropin-dependent precocious puberty. Pituitary. 2009;12:335-8.
22. Fuqua JS. Treatment and outcomes of precocious puberty. J ClinEndocrinolMetab. 2013;98:2198–207.
23. Partsch C, Heger S, Sippell WG. Management and outcome of central precocious puberty. Clin Endocrinol. 2002;56:129-48.
24. Carel JC, Lahlou N, Guazzarotti L, Joubert-Collin M, Roger M, Colle M, et al. Treatment of central precocious puberty with depot leuprorelin. French leuprorelin trial group. Eur J Endocrinol. 1995;132:699-704.
25. Higgins JP, Altman DG. Assessing risk of biasin included studies. Dalam: Higgins JP, Green S, editors. Cochrane handbook for systematic reviews of Interventions.Wiley-Blackwell. 2008:187-235.