A Research Study of How Well Macimorelin Works to Find Out if Children Have a Lack of Growth Hormone and How Safe it is

Inclusion Criteria: 1. Informed consent of subject, parent(s) or legally acceptable representative (LAR) of subject and child assent, if appropriate, must be obtained before any trial-related activities. Trial-related activities are any procedures that are carried out as part of the trial, including activities to determine suitability for the trial. 2. Male and female pediatric subjects from 2 to less than 18 years of age at the time of signing informed consent. 3. Indication for the performance of growth hormone stimulation test. 4. Presence of a height measurement minimum 6 and maximum 18 months prior to screening. Exclusion Criteria: 1. Established diagnosis of a disease that is sufficient to explain growth deficiency or metabolic disorders that are also associated with short stature (e.g., Turner syndrome, skeletal dysplasia's, celiac disease, etc.). 2. Ongoing growth hormone therapy. 3. Presence of hypothyroidism and/or adrenal insufficiency without adequate and stable replacement therapy treatment for at least 30 days prior to first GHST. 4. Treatment with drugs directly affecting the pituitary secretion of somatotropin (e.g., somatostatin analogues, clonidine, levodopa and dopamine agonists) or provoking the release of somatostatin (antimuscarinic agents e.g., atropine). 5. Medical history of ongoing clinically symptomatic psychiatric disorders. 6. 2nd or 3rd degree atrioventricular-block, prolongation of the QRS complex over 120 milliseconds, prolongation of the QTc interval over 450 milliseconds, or any other clinically significant abnormal electrocardiogram results at the V2 pre-dose electrocardiogram (ECG) as judged by the investigator. 7. Previous participation in this trial. Participation is defined as signed informed consent. 8. Participation in any clinical trial of an approved or non-approved investigational medicinal product within 30 days before screening. 9. Known or suspected hypersensitivity to trial product(s) or related products; 10. Any disorder, which in the investigator's opinion might jeopardize subject's safety or compliance with the protocol. 11. Concomitant treatment with any drugs that might prolong QT/QTc Note: A subject who receives such treatment will not be a candidate for this study, if his/her condition does not allow for a treatment-free period of at least 5 elimination half-lives of the drug that might prolong QT/QTc before the GHST; 12. Elevation of laboratory parameters indicating hepatic or renal dysfunction or damage (aspartate amino transferase (AST), alkaline phosphatase (ALT), gamma-glutamyl transferase (GGT) \> 2.5 x upper limit of normal (ULN); creatinine or bilirubin \> 1.5x ULN); 13. Current active malignancy other than non-melanoma skin cancer; 14. Female of child-bearing potential and not using an adequate contraceptive method (adequate contraceptive measures as required by local regulation or practice). 15. Male of reproductive age who or whose partner(s) is not using an adequate contraceptive method (adequate contraceptive measures as required by local regulation or practice). 16. Lack of ability or willingness to give informed consent by the subject and/or his/her legal representative; 17. Anticipated non-availability for trial visits/procedures.