Compensatory growth (organ)

Compensatory growth is a type of regenerative growth that can take place in a number of human organs after the organs are either damaged, removed, or cease to function.^[1] Additionally, increased functional demand can also stimulate this growth in tissues and organs.^[2] The growth can be a result of increased cell size (compensatory hypertrophy) or an increase in cell division (compensatory hyperplasia) or both.^[3] For instance, if one kidney is surgically removed, the cells of the other kidney divide at an increased rate.^[1] Eventually, the remaining kidney can grow until its mass approaches the combined mass of two kidneys.^[1] Along with the kidneys, compensatory growth has also been characterized in a number of other tissues and organs including:

• The adrenal glands^[4][5]
• The heart^[5][6]
• Muscles^[5]
• The liver^[5][7]
• The lungs^[8]
• The pancreas (beta cells and acinar cells)^[7]
• The mammary glands^[5]
• The spleen (where bone marrow and lymphatic tissue undergo compensatory hypertrophy and assumes the spleen function during spleen injury)^[5]
• The testicles^[5]
• The thyroid gland^[5][9]
• The turbinates of the nose^{[medical citation needed]}

A large number of growth factors and hormones are involved with compensatory growth, but the exact mechanism is not fully understood and probably varies between different organs.^[1] Nevertheless, angiogenic growth factors which control the growth of blood vessels are particularly important because blood flow significantly determines the maximum growth of an organ.^[1]

Compensatory growth may also refer to the accelerated growth following a period of slowed growth, particularly as a result of nutrient deprivation.

• Hyperplasia
• Hypertrophy
• Cellular adaptation