A term newborn delivered in a cold delivery room maintains its core temperature without shivering. The primary mechanism of heat generation in the first days of life is:

• A Shivering in skeletal muscle triggered by hypothalamic cold receptors
• B Increased activity of the sodium-potassium ATPase in white adipose tissue
• C Uncoupled oxidation in brown adipose tissue mediated by uncoupling protein 1 ✓
• D Futile cycling between glycolysis and gluconeogenesis in hepatocytes

Explanation

Neonatal non-shivering thermogenesis occurs in brown adipose tissue, located around the neck, interscapular area and perirenal region. Norepinephrine activates hormone-sensitive lipase, releasing fatty acids, while uncoupling protein 1 dissipates the mitochondrial proton gradient so substrate energy is released as heat instead of ATP. Shivering is poorly developed in newborns, which makes brown fat the dominant thermogenic organ in early neonatal life.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.