What is the role of lab testing in the workup of pediatric growth failure (failure to thrive)?

Updated: Nov 05, 2018
  • Author: Andrew P Sirotnak, MD; Chief Editor: Caroly Pataki, MD  more...
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The history and physical examination should guide any laboratory or ancillary testing. Most infants and children with growth failure related to environmental factors need very limited laboratory screenings. In the young infant or child, a few prudent baseline tests maybe indicated.

Initial and follow-up newborn screening tests, as follows:

  • CBC count - WBC and RBC indices for possible indication of occult infection, microcytic or hemolytic anemias, or immune deficiency

  • Urinalysis and culture - Hydration status (if warranted) with specific gravity, evidence of infection, renal tubular acidosis

  • Renal function - Serum electrolytes, BUN, and creatinine levels

  • Liver function - Liver function tests considered in children with signs of protein wasting or organomegaly

Additional testing as needed or indicated, as follows:

  • Human immunodeficiency virus (HIV) testing if risk factors are noted or if history and examination are at all suggestive

  • Sweat test for cystic fibrosis

  • Zinc level reported to be low in malnourished infants and children

  • Metabolic and endocrinology screening (only as needed)

  • Tuberculosis testing

  • Stool studies

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