Children with kwashiorkor have characteristic skin lesions with alternating zones of hyperpigmentation, desquamation, and hypopigmentation, giving a “flaky paint” appearance. Hair changes include loss of color or alternating bands of pale and darker color, straightening, fine texture, and loss of firm attachment to the scalp. Other features that distinguish kwashiorkor from marasmus include an enlarged, fatty liver (resulting from reduced synthesis of the carrier protein component of lipoproteins) and the development of apathy, listlessness, and loss of appetite. As in marasmus, vitamin deficiencies are likely to be present, as are defects in immunity and secondary infections. In kwashiorkor, the inflammation caused by infection produces a catabolic state that aggravates the malnutrition. As already mentioned, marasmus and kwashiorkor represent two ends of a spectrum, and considerable overlap exists.
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In the United States, secondary malnutrition often develops in chronically ill, older, and bedridden patients. It is estimated that more than 50% of older residents in nursing homes in the United States are malnourished. Weight loss of more than 5% resulting from malnutrition increases the risk of mortality in nursing home patients by almost 5-fold. A particularly severe form of secondary malnutrition, called cachexia, often develops in patients with advanced cancer (Chapter 6). The wasting is all too apparent and often presages death. Although loss of appetite may partly explain it, cachexia may appear before the appetite decreases. The underlying mechanisms are complex, but appear to involve cytokines secreted by tumor cells, particularly TNF, which are released as part of the host response to advanced tumors. These factors directly stimulate the degradation of skeletal muscle proteins, and also stimulate fat mobilization from lipid stores.
ThehallmarkanatomicchangesinSAMare(1)growthfailure, (2)peripheraledemainkwashiorkor,and(3)lossofbodyfatandatrophyofmuscle,moremarkedinmarasmus.Theliver inkwashiorkor,butnotinmarasmus,isenlargedandfatty;superimposedcirrhosisisrare.
Inkwashiorkor(rarelyinmarasmus)thesmall bowel showsadecreaseinthemitoticindexinthecryptsoftheglands,associatedwithmucosalatrophyandlossofvilliandmicrovilli.Insuchcasesconcurrentlossofsmallintestinalenzymesoccurs,mostoftenmanifestedasdisaccharidasedeficiency.Hence,infantswithkwashiorkorarelactateintolerantinitiallyandmaynotrespondwelltofull-strength,milk-baseddiets.Withtreatment,themucosalchangesarereversible.
Thebone marrow inbothkwashiorkorandmarasmusmaybehypoplastic,mainlyasaresultofdecreasednumbersofredcellprecursors.Thus,anemiaisusuallypresent,mostoftenhypochromic,microcyticduetoirondeficiency,butaconcurrentdeficiencyoffolatemayleadtoamixedmicrocytic-macrocyticanemia.
Thebrain ininfantswhoareborntomalnourishedmothersandwhosufferfromSAMduringthefirst1or2yearsoflifehasbeenreportedbysomeinvestigatorstoshowcerebralatrophy,areducednumberofneurons,andimpairedmyelinationofwhitematter.
Manyotherchangesmaybepresent,including(1)thymicandlymphoidatrophy(moremarkedinkwashiorkorthaninmarasmus),(2)anatomicalterationsinducedbyintercurrentinfections,particularlywithendemichelminthsandotherparasites,and(3)deficienciesofotherrequirednutrientssuchasiodineandvitamins.