The physiologic basis for FTT of any etiology is inadequate nutrition for weight gain to occur. Thus, nonorganic FTT may result from various situations, ranging from a severely disturbed or ill child, whose care poses a major challenge to even the most competent parent, to a potentially undemanding and compliant child being cared for by a mentally ill parent lacking adequate social, emotional, financial, cognitive, or physical resources. Within these extremes are mother-child mismatches, in which the child's demands, although not pathologic, cannot be adequately met by the mother, who might, however, do well with a child who has different needs or even with the same child under different circumstances. In mixed FTT, organic and nonorganic FTT overlap. The physician must ascertain the relative contributions of each to the child's abnormal growth.
Weight is the most sensitive indicator of nutritional status.
Reduced linear growth usually indicates more severe, prolonged malnutrition. If the child does not gain weight satisfactorily, he is usually admitted to the hospital so that all necessary observations can be made and diagnostic tests performed quickly. Optimally, evaluation is multidisciplinary, involving a physician, a nurse, a nutritionist, an expert in child development, a social worker, and a psychiatrist or psychologist. The child's feeding behaviors with health care practitioners and with the parents must be observed, whether the setting is inpatient or outpatient. Engaging the parents as co-investigators is essential.