insulin-like growth factors
Summary
Peptide hormones (IGF-1, IGF-2) that promote growth, metabolism, and differentiation, structurally similar to insulin. Mediate many effects of growth hormone and regulated by GH, nutrition, and thyroid hormone.
Detail
IGF-1 is the primary effector of growth hormone: GH stimulates IGF-1 synthesis primarily from the liver. IGF-1 promotes protein synthesis, amino acid uptake, lipolysis, and glucose utilization, and stimulates chondrocyte proliferation for linear growth. IGF-2 is predominantly expressed during fetal development. Excess IGF-1 (from GH-secreting pituitary adenoma) causes acromegaly/gigantism; deficiency results in growth failure. IGF binding proteins regulate bioavailability. Recombinant IGF-1 treats growth hormone insensitivity syndrome (Laron dwarfism).
Sources
- First Aid for the USMLE Step 1
- Pathoma
- Harrison's Principles of Internal Medicine
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