Muscle Quality and Risk of Metabolic Syndrome in Adult Patients with Inherited Metabolic Diseases

Adult patients with several Inherited Metabolic Diseases (IMD) follow diets controlled in proteins, rich in carbohydrates, and free amino acids formulae, which cause hyperinsulinism and ectopic fat. Previous studies showed IMD adult patients have a higher prevalence of metabolic syndrome and their complications [1]. Recently, ultrasound [US) has been validated for malnutrition, assessing muscle quality subjectively [2]. Higher echo intensity (EI) is associated with poorer muscle quality and functional results in aging [3] and other clinical settings, but it has never been evaluated in IMD. US measurements were conducted on 19 IMD patients and 6 healthy controls at Hospital Universitario de Badajoz (HUB) to assess EI, anthropometry, bioimpedance, and biochemistry. The HUB ethics committee approved the protocol and informed consent. Statistics were made with Jamovi. The mean age was 29.9 (range 18-47) in IMD patients vs. 33.7 (26-47) in controls. The distribution of IMD is shown in Figure 2. The mean EI in IMD was 56.9 (60.9 in PKU) vs. 54.4 in controls, NOT being the differences statistically significant (t- Student p =0.633; in PKU, p =0.246). The box plot is shown in Figure 3. IMD patients had excess body fat in a variable degree depending on the method (Figure 4): anthropometry, BIA, preperitoneal fat or myosteatosis. 40% had insulin resistance by HOMA, 20% prediabetes by HbA1c, 58.8% had low HDL-cholesterol levels, and 29.4% had hypertriglyceridemia. Insulin resistance status is shown in Figure 5. Obesity by anthropometry was significantly correlated with subcutaneous abdominal and preperitoneal fat by ultrasound and fat mass by BIA. Fat mass by BIA was correlated to preperitoneal fat, and fat-free mass by BIA with HOMA and degree of metabolic control of IMD. Muscle quality, by an objective tool, such as echo intensity, is worse in patients with IMD than in controls, reflecting poorer muscle metabolic condition and a higher risk of metabolic syndrome. It is not statistically significant, probably due to the small sample size. The prevalence of obesity and other metabolic syndrome components is higher in IMD patients than in the general population of the same age. Body composition analysis by BIA and nutritional ultrasound can help to identify patients at risk of metabolic syndrome before biochemical markers show.