Monday 23 March 2009
Kwashiorkor, in contast to marasmus, occurs when protein deprivation is relatively greater than the reduction in total calories. This is the most common form seen in African children who have been weaned (often too early, owing to the arrival of another child) and are subsequently fed an exclusively carbohydrate diet. The prevalence of kwashiorkor is also high in impoverished countries of Southeast Asia.
Less severe forms may occur worldwide in persons with chronic diarrheal states in which protein is not absorbed or in those with conditions in which chronic protein loss occurs (e.g., protein-losing enteropathies, the nephrotic syndrome, or after extensive burns).
Kwashiorkor is a more severe form of malnutrition than marasmus. Unlike marasmus, marked protein deprivation is associated with severe loss of the visceral protein compartment, and the resultant hypoalbuminemia gives rise to generalized, or dependent, edema.
The weight of children with severe kwashiorkor is typically 60% to 80% of normal.
However, the true loss of weight is masked by the increased fluid retention (edema). In further contrast to marasmus, there is relative sparing of subcutaneous fat and muscle mass. The modest loss of these compartments may also be masked by edema.
Children with kwashiorkor have characteristic skin lesions, with alternating zones of hyperpigmentation, areas of desquamation, and hypopigmentation, giving a "flaky paint" appearance.
Hair changes include overall loss of color or alternating bands of pale and darker hair, straightening, line texture, and loss of firm attachment to the scalp.
Other features that differentiate kwashiorkor from marasmus include an enlarged, fatty liver (resulting from reduced synthesis of carrier proteins) and a tendency to develop early apathy, listlessness, and loss of appetite. As in marasmus, other vitamin deficiencies are likely to be present, as are defects in immunity and secondary infections. The latter add to the catabolic state, thus setting up a vicious circle.
The liver in kwashiorkor, but not in marasmus, is enlarged and fatty; superimposed cirrhosis is rare.
In kwashiorkor (rarely in marasmus), the small bowel shows a decrease in the mitotic index in the crypts of the glands, associated with mucosal atrophy and loss of villi and microvilli. In such cases, concurrent loss of small intestinal enzymes occurs, most often manifested as disaccharidase deficiency. Hence, infants with kwashiorkor initially may not respond well to a full-strength, milk-based diet. With treatment, the mucosal changes are reversible.
The bone marrow in both kwashiorkor and marasmus may be hypoplastic, mainly because of decreased numbers of red cell precursors. How much of this derangement is due to a deficiency of protein and folates or to reduced synthesis of transferrin and ceruloplasmin is uncertain. Thus, anemia is usually present, most often hypochromic microcytic anemia, but a concurrent deficiency of folates may lead to a mixed microcytic-macrocytic anemia.