Human physiology — Human growth hormone (hGH, somatotropin) is secreted by which endocrine source in the body?

Introduction / Context:
Human growth hormone (hGH) is central to linear growth, metabolism, and tissue repair. Knowing its source is essential for interpreting endocrine feedback loops and disorders such as gigantism, acromegaly, and growth hormone deficiency.

Given Data / Assumptions:

• Endocrine regulation involves hypothalamic releasing/inhibiting factors.
• hGH acts on liver and tissues, partly via insulin-like growth factor 1 (IGF-1).
• Pituitary anatomy distinguishes anterior and posterior lobes with different hormones.

Concept / Approach:
hGH is produced by somatotroph cells in the anterior pituitary gland. The hypothalamus regulates its secretion through growth hormone–releasing hormone (GHRH) and somatostatin (growth hormone–inhibiting hormone). The pancreas and thyroid produce other hormones (insulin, thyroxine) with separate roles.

Step-by-Step Solution:

Verification / Alternative check:
Clinical testing (GH stimulation/suppression tests) targets pituitary output; pituitary adenomas drive excess GH in acromegaly, confirming the gland as the source.

Why Other Options Are Wrong:

• Hypothalamus: regulates GH but does not secrete the hormone itself into systemic circulation.
• Pancreas/thyroid: endocrine organs for other hormones.
• “None of these” is incorrect; the pituitary is correct.

Common Pitfalls:
Confusing hypothalamic regulation with hormone production; the hypothalamus secretes GHRH and somatostatin, not GH.

Final Answer:
PITUITARY GLAND (anterior pituitary).