Definition and diagnosis of constitutional thinness: a systematic review

Abstract

The existing literature about the definition and diagnostic criteria of constitutional thinness (CT) appears equivocal. The present work systematically reviewed the criteria used in the diagnosis of adult individuals with CT (PROSPERO registration number: CRD42019138236). Five electronic bibliographic databases were searched between December 2018 and November 2019: MEDLINE, Embase, CENTRAL (Cochrane Library), Google Scholar and Clinical Trials. Search terms were combined with Medical Subject Headings terms. The search strategy included any clinical trials that enrolled adults with CT. Studies were systematically excluded if the state of thinness was not due to a well-identified constitutional origin. From the 689 references after duplicate removal, 199 studies were excluded based on title and 164 based on abstract. According to the inclusion and exclusion criteria, 291 other studies were removed. Finally, thirty-five studies remained at the end of the process. The analysis of these studies showed high heterogeneity in the diagnostic criteria of CT. A real need emerged to adopt a common terminology and to systematically exclude potential non-constitutional origins of thinness such as eating disorders, associated pathology or over-exercising, with validated tools. Weight history, physiological menses and weight gain resistance are also important criteria to consider. The present systematic review revealed that our medical and scientific approaches of CT need to be harmonised in terms of terminology and diagnostic criteria. Although further studies are needed, we finally proposed recommendations and a decision tree to help in the recognition and diagnosis of CT.

Los pacientes con delgadez constitucional presentan un fenotipo diferente al de los pacientes con trastornos de la alimentación

“…A diferencia de otras entidades, este tipo de delgadez no suele acompañarse de trastornos de alimentación, enfermedades sistémicas, desnutrición o sobre-ejercitación. Sin embargo, su presencia suele despertar preocupación y motivar la búsqueda de causas patológicas asociadas, tanto por parte de los pacientes como de los profesionales de la salud 2 . Esto suele conducir a la estigmatización de la población afectada, siendo la anorexia nerviosa el principal diagnóstico diferencial con el cual se la suele confundir.…”

Constitutional thinness and anorexia nervosa differ on a genomic level

“…In some cases, the phenotypic definition is augmented by a family history of thinness as an additional criterion [4]. However, definitions of constitutional thinness vary considerably across studies [5]. The prevalence of constitutional thinness is unknown [1], but is likely to be less than 0.4% for men and less than 2.7% for women (underweight from all causes) [6].…”

Constitutional thinness: body fat metabolism and skeletal muscle are important factors

“…The excellent review by Bailly et al (1) highlights various abnormal clinical conditions important to help rule out constitutional thinness, including eating disorders, associated pathology and over-exercise, along with a history of weight, physiological menses and weight gain resistance. However, two additional factors that can significantly influence health should also be considered in constitutional thinness: body fat metabolism and skeletal muscle strength.…”