Which condition is characterized by a failure to thrive and is associated with malnutrition due to inadequate protein intake?

The condition characterized by a failure to thrive and associated with malnutrition due to inadequate protein intake is Kwashiorkor. This condition commonly arises in children who have transitioned from breastfeeding to a diet lacking sufficient protein, despite possibly having adequate caloric intake.

Kwashiorkor is marked by symptoms such as edema, irritability, an enlarged abdomen, and changes in skin and hair pigmentation, which are indicative of severe nutritional deficiencies. The absence of adequate protein disrupts bodily functions and significantly affects growth and development, leading to the described failure to thrive.

In contrast, Marasmus results primarily from caloric deficiency rather than a specific lack of protein, leading to severe wasting but with less swelling and edema compared to Kwashiorkor. Scurvy is related to Vitamin C deficiency and can lead to growth defects, but it is not directly tied to protein malnutrition. Rickets involves a deficiency in Vitamin D, calcium, or phosphate, leading to bone weakness and deformities rather than protein deficiency specifically. Therefore, the defining characteristics of Kwashiorkor distinctly align with the symptoms described in the question.