Evaluation of alterations of serum leptin concentrations and body composition during catch-up growth

SUMMARY EVALUATION OF ALTERATIONS OF SERUM LEPTIN CONCENTRATIONS AND BODY COMPOSITION DURING CATCH-UP GROWTH AIM: In this study, leptin concentrations were determined in children with mild to moderate malnutrition aged 1 - 9 years, and alterations of leptin concentrations with appropiate nutritional support were investigated. Additionally, relationship between alterations of body composition and leptin concentrations were evaluated during catch-up growth. SUBJECTS AND METHODS: Thirty otherwise healthy outpatients with mild to moderate malnutrition secondary to inadequate energy intake (mean age 5 ± 2.4 years; range 1 - 9 years; male/female ratio: 9/21) were enrolled in the study. Healthy children who had normal anthropometric data in spite of inadequate energy intake (mean age 4.2 ±2.1 years; range 1-9 years; male/female ratio: 20/31) constituted the control group. At the beginning of the study anthropometric values were obtained, energy and protein intake for three days were recorded, blood samples for basal serum leptin concentrations were drawn from each patient and controls. Patients in the control group were evaluated once, at the beginning of the study. After recommending appropiate nutritional support, the patients (n=30) were followed monthly in outpatient clinics. The anthropometric data, energy and protein intake for the last three days prior to the date of follow-up were recorded each month. When a patient's weight for height value reached to % 90 of standard (50 percentile for a child with same gender and age), he/or she was considered as "going trough catch up growth". Blood samples were obtained from each patient at 1-, 3rd and 6th month of follow-up for assessment of serum leptin concentrations. RESULTS: There were significant differences in TSF, MAC, body weight % std., body height % std., weigth for height % std., BMI % std., TSF % std., AMA % std. between two groups. In patient group, these values were less than control group (p<0.05). However, calculated energy deficit in the patient group was significantly less than control group (p=0.009). Basal mean serum leptin concentrations for the patient group was 2.9 ± 2.4 ng/mL, whereas, in the control group it was 4.9 ±3.1ng/mL (p=0.002). According to age and gender, the patient and control groups were divided into six subgroups. Among the female patients, the mean leptin concentration of the 6 - 9 year old group was higher than 1 - 3 year 1 1 month old group (p=0.041). On the other hand, there was no difference for mean leptin concentrations between other subgroups (p>0.05). There was a positive correlation between basal serum leptin concentrations and weight for height % std. in the patient group (r=0.392, p=0.032). Similary, no correlations were found between serum leptin concentrations versus TSF, MAC, body weight % std., body height % std., TSF % std., BMI % std., AMA % std., energy-protein intake and energy deficiency. However, there was positive correlations between serum leptin concentrations versus body height % std. (r=0.292, p=0.038), weight for height % std. (r=0.433, p=0.01) and BMI % std. (r=0.317, p=0.024) in controls. By regression analysis, BMI % std. was found to be the most effective nutritional parameter affecting serum leptin concentration (t=2.524, p=0.014). Twenty-two of thirty patients who were given appropiate nutritional support showed catch-up growth. Mean basal serum leptin concentrations for the patient group with catch-up growth was 3.3 ± 2.7 ng/mL. At the time of catch-up growth, mean serum leptin concentration was 6.7 ± 4 ng/mL. This increase was found to be statistically significant (p<0.001). The mean basal serum leptin concentration of the patients who did not show catch-up growth (n=8) was 1.8 ± 0.7 ng/mL. At sixth month of follow-up mean serum leptin concentration was 1.8 ± 1 ng/mL. There was no difference between two values (p>0.05). The mean basal serum leptin concentration of patients who showed catch-up growth (n=22) was similar with the ones who did not (n=8) (p>0.05). Between these groups there was no difference in energy intake before nutritional support was recommended (p>0.05). However, in the group with catch-up growth, the energy intake was significantly higher at the time of catch-up growth as compared with the time before the nutritional support was given (p<0.001). This increased energy intake was also present in the group who did not show catch-up growth (p=0.012). However, the energy intake of the catch-up growth group at the time of catch-up growth was higher than the group who did not show catch-up growth at six months follow-up (p=0.001). There was a positive correlation between serum leptin concentrations and TSF % std. value at the time of catch-up growth (r=0.488, p=0.021). This correlation was not found in the group who did not show catch-up growth. To make a better comparison, a new anthropometric data- matched control group (n=20) was constituted by selecting children from the main 5 IX. YÜKSnCÖCRlTtM KUMDU».OK0MAKTAIYQN ~*control group (n=51). The mean energy and protein intake of the patients with catch up growth at the time of catch-up growth was found to be higher than tiie new control group (p<0.001). Similary, mean serum leptin concentration was higher in patients with catch-up growth at the time of catch-up growth than the data-matched controls (p=0.001). CONCLUSION: Mean serum leptin concentration of mild to moderate malnourished children was lower than healthy controls. There was a positive correlation between serum leptin concentrations and weight for height % std. in mild to moderate malnourished children. We found that there might be an association between increased serum leptin concentrations and catch-up growth. Additionally, there was a positive correlation between serum leptin and TSF % std. value at the time of catch up growth. Moreover, absence of a relationship between serum leptin concentrations and TSF % std. in the group of patients who did not show catch-up growth suggests that, TSF % std. might be an early marker for catch-up growth. The fact that there was no difference in the basal serum leptin concentrations of the group of patients who showed catch-up growth and who did not, suggests that, one can not predict the outcome of nutritional support of children with mild to moderate malnutrition based on serum leptin concentrations prior to the therapy. KEY WORDS: Mild/moderate malnutrition, leptin, catch-up growth.