Lipohypertrophy
Encyclopedia
Lipohypertrophy is a medical
term that refers to a lump under the skin
caused by accumulation of extra fat at the site of many subcutaneous injection
s of insulin
. It may be unsightly, mildly painful, and may change the timing or completeness of insulin action
. It is a common, minor, chronic complication of diabetes mellitus.
Typical injection site hypertrophy is several inches or cm across, smoothly rounded, and somewhat firmer than ordinary subcutaneous fat. There may be some scar
tissue as well, but the major component is adipose tissue
, as insulin exerts a hypertrophic
effect adipose cells. To avoid lipohypertrophy, persons with diabetes mellitus
who inject insulin daily for an extended period of time are advised to rotate their injections among several areas (usually upper, outer arms, outer thighs, abdomen below and around the umbilicus
, and the upper parts of the buttocks. Rotation charts to aid avoidance of lipohypertrophy are often provided as part of diabetes education.
Lipohypertrophy usually will gradually disappear over months if injections in the area are avoided.
It is a common misconception that the lump is largely scar tissue, as injection site hypertrophy is much rarer and milder with injections of other hormones and medications which lack the specific ability of insulin to stimulate adipose hypertrophy.
In a sense, the "opposite" of injection site lipohypertrophy is injection site lipoatrophy
, in which the subcutaneous fat around an injected area "melts away" over a few weeks or months, leaving unsightly, well-demarcated depressions in the skin. The mechanism of this local lipoatrophy is not understood and may involve autoimmunity or local inflammation.
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
term that refers to a lump under the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
caused by accumulation of extra fat at the site of many subcutaneous injection
Subcutaneous injection
A subcutaneous injection is administered as a bolus into the subcutis, the layer of skin directly below the dermis and epidermis, collectively referred to as the...
s of insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
. It may be unsightly, mildly painful, and may change the timing or completeness of insulin action
Pharmacokinetics
Pharmacokinetics, sometimes abbreviated as PK, is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism...
. It is a common, minor, chronic complication of diabetes mellitus.
Typical injection site hypertrophy is several inches or cm across, smoothly rounded, and somewhat firmer than ordinary subcutaneous fat. There may be some scar
Scar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
tissue as well, but the major component is adipose tissue
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
, as insulin exerts a hypertrophic
Hypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number...
effect adipose cells. To avoid lipohypertrophy, persons with diabetes mellitus
Diabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
who inject insulin daily for an extended period of time are advised to rotate their injections among several areas (usually upper, outer arms, outer thighs, abdomen below and around the umbilicus
Navel
The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...
, and the upper parts of the buttocks. Rotation charts to aid avoidance of lipohypertrophy are often provided as part of diabetes education.
Lipohypertrophy usually will gradually disappear over months if injections in the area are avoided.
It is a common misconception that the lump is largely scar tissue, as injection site hypertrophy is much rarer and milder with injections of other hormones and medications which lack the specific ability of insulin to stimulate adipose hypertrophy.
In a sense, the "opposite" of injection site lipohypertrophy is injection site lipoatrophy
Lipoatrophy
Lipoatrophy is the term describing the localized loss of fat tissue. This may occur as a result of subcutanous injections of insulin in the treatment of diabetes, from the use of human growth hormone or from subcutanous injections of Copaxone used for the treatment of multiple sclerosis. In the...
, in which the subcutaneous fat around an injected area "melts away" over a few weeks or months, leaving unsightly, well-demarcated depressions in the skin. The mechanism of this local lipoatrophy is not understood and may involve autoimmunity or local inflammation.