Abstract: BACKGROUND:  Muscle tissue plays an important role in completing exercise, maintaining body position and maintaining homeostasis in the body. Muscle quality assessment and intervention can help to improve the quality of life of patients and shorten the length of hospital stay, which has become a research hotspot in recent years. 
OBJECTIVE: To explore the related influencing factors of muscle mass decline by systematic assessment of limb muscle mass in patients undergoing allogeneic hematopoietic stem cell transplantation.
METHODS: 146 patients who underwent allogeneic hematopoietic stem cell transplantation were selected as the study subjects. The general information questionnaire was used to collect patients’ age, sex, and education degree. Muscle mass was measured by bioelectrical impedance analysis. Patient’ body mass index, arm muscle circumference, triceps skinfold thickness, body fat rate, conditioning regimen, antithymocyte globuin dose, HLA matching, graft source, albumin, prealbumin and total protein, and ECOG score were collected. The t test, chi square test and binary logistic regression analysis were used to analyze appendicular skeletal muscle. The study was approved by the Ethics Committee of Guangzhou First People’s Hospital. All patients agreed to participate in the study and signed informed consent.
RESULTS AND CONCLUSION: (1) Muscle mass loss was observed in 89 patients (60.9%) of allogeneic hematopoietic stem cell transplantation, including 51 males and 38 females. Compared with the reference values of the Chinese normal population, it was found that allogeneic hematopoietic stem cell transplantation patients showed lower levels of muscle mass, arm muscle circumference and triceps skinfold thickness, but body fat rate increased significantly, with statistically significant differences (P < 0.05). (2) The patients were divided into the low muscle mass group and the normal muscle mass group. The differences in body weight and body mass index between the two groups were statistically significant (P < 0.05), but the differences in biochemical indexes such as albumin, prealbumin and total protein were not statistically significant (P > 0.05). (3) A single factor comparison of muscle mass showed that there were statistically significant differences in weight, body mass index, conditioning regimen and ECOG score (P < 0.05). Binary logistic regression showed that high body mass index was a protective factor of muscle mass in patients with allogeneic hematopoietic stem cell transplantation (OR=52.804, P < 0.05), and high ECOG score was a risk factor (OR=0.458, P < 0.05). (4) Results indicate that allogeneic hematopoietic stem cell transplantation patients generally have decreased muscle mass in their extremities, and muscle mass can reflect the nutritional status of patients earlier than blood biochemical indicators such as albumin, providing earlier warning for nutritional intervention. Therefore, early evaluation of skeletal muscle mass in allogeneic hematopoietic stem cell transplantation patients should be conducted. 

Key words: stem cells, allogeneic, hematopoietic stem cells, stem cell transplantation, limbs, muscle mass, sarcopenia, body composition, influencing factors