Inclusion Criteria:
Suspected AGHD Subjects (Groups A, B, and C):
* Age ≥ 18 years and ≤ 65 years, male or female.
* Suspected AGHD, meeting at least one of the following criteria:
* Congenital structural/gene defects in the hypothalamus or pituitary gland, or
* History of surgery or radiotherapy in the hypothalamic or pituitary region, or
* Adult traumatic brain injury (TBI) or central nervous system (CNS) infection, or
* Confirmed deficiency of at least one pituitary hormone other than growth hormone (GH), or
* Idiopathic childhood-onset GHD.
* IGF-1 SDS \< 0.
* Willing and able to comply with the study procedures and voluntarily sign the informed consent form.
Matched Healthy Control Subjects (Group D):
* Age ≥ 18 years and ≤ 65 years, male or female.
* Matching criteria with Group A (subjects with highly suspected AGHD):
1. Sex;
2. Age;
3. BMI;
4. (If feasible) Estrogen use and administration route (oral, transdermal) in females:
Exclusion Criteria:
* Known or suspected hypersensitivity to growth hormone secretagogues (GHS) or their excipients or known allergy to insulin or its excipients.
* Clinically significant conditions newly diagnosed within 6 months before screening, making the subject unsuitable for ITT:
1. Chronic congestive heart failure (New York Heart Association (NYHA) Class III or higher);
2. Other significant cardiovascular/cerebrovascular diseases, e.g., uncontrolled severe hypertension, severe arrhythmia, stroke or transient ischemic attack (TIA), or confirmed coronary artery disease;
3. Traumatic brain injury (TBI).
* Short-acting GH therapy within 30 days before screening.
* Long-acting GH therapy within 90 days before screening.
* GH stimulation test performed within 7 days before the first dose.
* Abnormal thyroid function during screening, or any adjustment to thyroid hormone replacement therapy dosage prior to the first study dose.
* Abnormal gonadal function during screening, or any adjustment to testosterone/estrogen replacement therapy dosage prior to the first study dose.
* Abnormal adrenal function during screening, or any adjustment to glucocorticoid replacement therapy dosage prior to the first study dose.
* Type 1 diabetes diagnosed before screening, or uncontrolled Type 2 diabetes
* Body mass index (BMI) ≥40.0 kg/m².
* Major surgery (e.g., coronary bypass, hepatectomy/nephrectomy, gynecologic surgery) within 6 months before screening.
* Acute neurological, digestive, respiratory, circulatory, endocrine, or hematologic diseases within 3 months before screening, judged by the investigator to potentially affect drug absorption, distribution, metabolism, excretion (ADME), or safety evaluation.
* History or current diagnosis of malignancy (any type) before screening.
* Electrocardiogram (ECG) findings during screening indicating QTc interval \>450 ms, or history of corrected QT interval (QTc) prolongation, or other clinically significant ECG abnormalities, or use of medications known to prolong QTc interval.
* Sellar region MRI scan during screening showing untreated intracranial tumor growth.
* History of clinically symptomatic psychiatric disorders persisting at screening.
* History of Parkinson's disease or epilepsy persisting at screening.
* Females with positive blood human chorionic gonadotropin (hCG) during screening, or lactating females, or females planning pregnancy from screening through follow-up completion.
* Liver function abnormalities during screening
* Use of medications directly affecting pituitary GH secretion or somatostatin-releasing drugs within a period \>5 half-lives before first study dose.
* Use of strong cytochrome P450 family 3 subfamily A member 4/5 (CYP3A4/5) inhibitors or inducers.
* Participation in any other drug or medical device clinical trial within 1 month prior to screening, or screening occurring within 5 half-lives of the investigational drug (whichever is longer).
* Unwillingness to use protocol-specified contraception methods
* Other conditions deemed by the investigator to make the subject unsuitable for participation in this clinical trial.
