Laboratory Studies
The most helpful laboratory studies in assessing malnutrition in a child are hematological studies and laboratory studies evaluating protein status:
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Hematological studies should include a CBC count with RBC indices and a peripheral smear. This could also help exclude anemias from nutritional deficiencies such as iron, folate, and vitamin B-12 deficiencies.
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Measures of protein nutritional status include serum albumin, retinol-binding protein, prealbumin, transferrin, creatinine, and BUN levels. Retinol-binding protein, prealbumin, and transferrin determinations are much better short-term indicators of protein status than albumin. However, in the field, a better measure of long-term malnutrition is serum albumin because of its longer half-life.
Additional diagnostic evaluation includes the following:
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In children who have a history of adequate food intake and signs/symptoms of malnutrition, focus on identifying the cause of malnutrition. Perform laboratory studies based on information from a complete history and physical examination.
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Initial diagnostic laboratory studies include a CBC count, sedimentation rate, serum electrolytes, and urinalysis and culture. Stool specimens should be obtained if the child has a history of abnormal stools or stooling patterns or if the family uses an unreliable or questionable source of water.
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Additional studies may focus on thyroid functions or sweat chloride tests, particularly if height velocity is abnormal. Further diagnostic studies should be determined as dictated by the history and physical examination. For example, laboratory tests evaluating renal function, such as phosphorus and calcium, should be obtained in the presence of renal symptoms. Children with suspected liver disease should have triglyceride and vitamin levels obtained, while zinc levels should be obtained in patients with chronic diarrhea.
Celiac serology is a useful screening test and should be considered, especially if there is a family history of celiac disease or if other autoimmune diseases, such as type I diabetes mellitus, are present.
Other Tests
Other tests include the following:
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Practical nutritional assessment
Complete history, including a detailed dietary history
Growth measurements, including weight and length/height; head circumference in children younger than 3 years
Complete physical examination
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Sensitive measures of nutritional status and failure to thrive
- Percentiles:
- Weight or weight for height less than 3rd or 5th percentile on standard growth curves
- Standard Deviation Score
- Weight ,2 standard deviations below mean for gender and age
- Weight for height < 2 standard deviations below mean for gender and age
- Z scores*
- -2.0 less of weight for age or height for age or weight for height
- - *Z scores are calculated by (Observed weight-mean weight)/standard deviation of reference population
- Percentiles:
Height-for-age or weight-for-height measurements greater than 2 standard deviations below the mean for age
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Hormonal adaptation to the stress of malnutrition: The evolution of marasmus.
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A classic example of a weight chart for a severely malnourished child.
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This infant presented with symptoms indicative of a dietary protein deficiency, including edema and ridging of the toenails. Image courtesy of the Centers for Disease Control and Prevention.
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This infant presented with symptoms indicative of Kwashiorkor, a dietary protein deficiency. Note the angular stomatitis indicative of an accompanying Vitamin B deficiency as well. Image courtesy of the Centers for Disease Control and Prevention.
