© 2020, Anthony J. Jannetti Inc.. All rights reserved. Failure to thrive (FTT) is a complex problem affecting the infant, the biological mother, and their family. Discovering the cause of FTT is a complex process for the primary care provider (PCP), and involves clinical observation of feedings, and aggressive monitoring of growth and development with laboratory testing. The case presented addresses the systematic review of FTT diagnostic criteria and interventions. In this case, a simple and inexpensive creamatocrit measure-ment of breastmilk fat may find subtle deficiencies in nutrition at the first signs of FTT, possibly preventing expensive hospitalizations and accusations of child maltreatment. For the PCP, simple increase in caloric intake with aggressive evaluation and monitoring is necessary to improve weight gain of the infant with FTT before a hospital referral.