Lipodystrophy is a term used to describe a group of varying disorders which are characterized by abnormal loss of body fat over some or all body areas, with a strong tendency to develop insulin resistance.
Lipodystrophies may be classified on the basis of the distribution as well as the genetic contribution, into congenital and acquired varieties of generalized and partial lipodystrophy
The most common among the genetic subtypes are the congenital generalized lipodystrophy and the familial partial lipodystrophy, while among the acquired subtypes the most frequently seen are acquired generalized and acquired partial lipodystrophies. An increasingly seen subtype is that occurring in HIV patients on highly active antiretroviral therapy (HAART).
- Congenital generalized lipodystrophy is present from birth, as a loss of fat over the whole body, and is inherited in an autosomal recessive manner. It is three times more frequent in females. Many of these patients also develop autoimmune disease in childhood such as juvenile dermatomyositis.
- Familial partial lipodystrophy occurs as a patchy loss of fat over the trunk and the extremities, around the time of puberty, and is associated with autosomal dominant inheritance
- Acquired generalized lipodystrophy is marked by a gradual loss of fat all over the body and is usually associated with autoimmune disease.
- Acquired partial lipodystrophy is characterized by loss of fat over the upper extremities, face and neck, and trunk, often associated with the presence of complement 3 nephritic factor.
- HAART-associated lipodystrophy is seen in HIV patients on HAART which includes protease inhibitors or nucleoside analogs. The first signs manifest after 2-4 years of treatment
- Localized lipodystrophy is typically caused by insulin or steroid injections
Lipodystrophy may be accompanied by severe insulin resistance which in turn results in:
- Diabetes mellitus with its eventual sequelae such as neuropathy, renal disease and cardiovascular disease
- Hypertriglyceridemia which may result in acute pancreatitis
- Fatty liver which may cause cirrhosis
It is noteworthy that these dysmetabolic syndromes are more severe in individuals with a larger area involved in lipodystrophy. Thus localized lipodystrophy, such as that seen in patients who use insulin subcutaneous injections over the same spot repeatedly, has few such pathologic alterations and poses a cosmetic rather than medical problem.
Lipodystrophies are managed mainly by preventing dyslipidemia and diabetes, with their complications. This may be achieved by a diet with low levels of simple carbohydrates and most carbohydrate in the form of complex starches and sugars, along with protein and fat to delay absorption over a period of time. Other usual anti-diabetic therapies must be used as well, such as insulin sensitizers and other drugs, as well as insulin injections themselves. An appropriate diet with about 20-30% fat and 50-60% carbohydrates is often advised.
Overfeeding is not advised, as it may cause steatosis and worsen the other metabolic complications. It is to be particularly discouraged in children when feeding the child more and richer food is a natural response by caregivers to the troubling lack of increase in weight. The child’s food should supply enough energy to suffice for the natural exuberance and development of children. Energy restriction may lead to deficiency of some essential nutrients and adversely affect growth.
Exercise should be another component of the management plan as it can help to control metabolic dysfunctions. However, some patients have a higher risk of developing cardiomyopathy and these individuals should be fully evaluated for cardiac parameters before advising exercise, and rigorous exercise should be discouraged strongly. Again, if severe enlargement of the liver and/or the spleen is present, or if other contraindications to contact sports are present, swimming or other non-impact sports are to be recommended.
With generalized lipodystrophy, there is very often a significant lowering of leptin levels in blood, which has led to the use of metreleptin to restore leptin levels to normal and improve the metabolic parameters in such patients. This is because very low leptin levels may increase the appetite and thus worsen diabetes and other complications. The use of metreleptin improves metabolic performance with regard to blood lipid levels, higher insulin sensitivity and prevention of fatty liver to some extent.
The development of high blood cholesterol levels should be prevented by using specialized formula for feeding infants, and by the use of diets which are very low in fat in elderly patients. If acute pancreatitis is present, only parenteral nutrition should be administered until recovery is complete, and this should be followed by a diet containing less than 20 g/day of fat. Lipid-lowering drugs may be required if diet and lifestyle interventions are not adequate to reduce lipid levels.
If hypertension develops, the patient may require treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, which have the additional advantage of preventing proteinuria. Fatty changes in the liver are difficult to treat.