Saturday, July 8, 2017

Introduction To Malnutrition

Malnutrition results from inadequate intake or abnormal GI assimilation of dietary calories, excessive energy expenditure, or altered metabolism of energy supplies by an intrinsic disease process.

Both outpatients and inpatients are at risk for malnutrition if they meet one or more of the following criteria:
• Unintentional loss of >10% of usual body weight in the preceding 3 months
• Body weight <90% of ideal for height.
• Body mass index (BMI: weight/height2 in kg/m2) <18.5

Two forms of severe malnutrition can be seen:

  1. marasmus, which refers to generalized starvation that occurs in the setting of chronically decreased energy intake without systemic inflammation, and 
  2. kwashiorkor, which refers to selective protein malnutrition due to decreased protein intake and catabolism in the setting of acute, life-threatening illnesses or chronic inflammatory disorders. Aggressive nutritional support is indicated in kwashiorkor to prevent infectious complications and poor wound healing.

The major etiologies of malnutrition are 
  • starvation,
  • stress from surgery or severe illness, and 
  • mixed mechanisms. 
Starvation results from decreased dietary intake (from poverty, chronic alcoholism, anorexia nervosa, fad diets, severe depression, neurodegenerative disorders, dementia, or strict vegetarianism; abdominal pain from intestinal ischemia or pancreatitis; or anorexia associated with AIDS, disseminated cancer, heart failure, or renal failure) or decreased assimilation of the diet (from
pancreatic insufficiency; short bowel syndrome; celiac disease; or esophageal, gastric,or intestinal obstruction). 

Contributors to physical stress include fever, acute trauma, major surgery, burns, acute sepsis, hyperthyroidism, and inflammation as occurs in pancreatitis, collagen vascular diseases, and chronic infectious diseases such as tuberculosis or AIDS opportunistic infections. 

Mixed mechanisms occur in AIDS, disseminated cancer, chronic obstructive pulmonary disease, chronic liver disease, Crohn’s disease, ulcerative colitis, and renal failure.

Clinical Features
General: weight loss, temporal and proximal muscle wasting, decreased skin-fold thickness
Skin, hair, and nails: easily plucked hair (protein deficiency); sparse hair (protein, biotin, zinc deficiency); coiled hair, easy bruising, petechiae, and perifollicular hemorrhages (vitamin. C deficiency ); “flaky paint” rash of lower extremities (zinc deficiency); hyperpigmentation of skin in exposed areas (niacin, tryptophan deficiency); spooning of nails (iron deficiency)
Eyes: conjunctival pallor (anemia); night blindness, dryness, and Bitot spots (vitamin. A deficiency ); ophthalmoplegia (thiamine deficiency)
Mouth and mucous membranes: glossitis and/or cheilosis (riboflavin, niacin, vitamin. B12,
pyridoxine, folate deficiency), diminished taste (zinc deficiency ), inflamed and bleeding gums (vitamin. C deficiency )
Neurologic: disorientation (niacin, phosphorus deficiency); confabulation, cerebellar gait, or
past pointing (thiamine deficiency); peripheral neuropathy (thiamine, pyridoxine, vitamin. E deficiency); lost vibratory and position sense (vitamin. B12 deficiency)
Other: edema (protein, thiamine deficiency), heart failure (thiamine, phosphorus deficiency), hepatomegaly (protein deficiency)

Laboratory findings in protein malnutrition include a low serum albumin, low total iron-binding capacity, and anergy to skin testing. Specific vitamin deficiencies also may be present.

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