Quick Facts
The perirenal fat capsule is the investment of fat surrounding the fibrous capsule of the kidney and continuous at the hilum with the fat in the renal sinus (Dorland, 2011).
Structure and/or Key Features
The perirenal fat is composed of adipose tissue that surrounds the kidneys and the suprarenal glands. It envelopes the fibrous capsules and is held tight around the organs via the renal fascia (Toldt’s fascia). This fat is typically more solid than normal fat.
In neonates, the perirenal fat capsule has a brown appearance due to the number of iron-containing mitochondria. However, the brown adipose tissue is thought to diminish gradually over the first ten years of life (Cantisani et al., 2003).
Anatomical Relations
The perirenal fat capsule is superjacent to the capsule of the suprarenal gland and kidney and is subjacent to the renal fascia (Toldt’s fascia) which tightly wraps it around the organs.
Function
The perirenal fat capsule serves numerous functions. It provides both protection and structural support to the kidneys and suprarenal glands, by stabilizing their anatomical position. Its primary function is yet to be fully elucidated but is thought to play a role in thermoregulation; generating heat via non-shivering thermogenesis due to its rich vascular supply.
List of Clinical Correlates
—Nephroptosis
References
Cantisani, V., Mortele, K. J., Glickman, J. N., Ricci, P., Passariello, R., Ros, P. R. & Silverman, S. G. (2003) Large retroperitoneal hibernoma in an adult male: CT imaging findings with pathologic correlation. Abdom Imaging, 28(5), 721-4.
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
