The relationship between serum irisin, thyroid function and body composition in patients with chronic kidney disease.

Aims and Objective: Chronic kidney disease (CKD) is associated with metabolic alterations like dyslipidemia, sarcopenia, protein catabolism, insulin resistance, altered body composition and energy expenditure. Thyroxine and novel adipo-myokine irisin have physiological role in energy metabolism. CKD patients have reduced levels of serum thyroxine and irisin. The decreased serum concentration of irisin and thyroxine in CKD patient might have relation with these metabolic alterations. The aim of this study was to investigate whether the serum irisin differs in CKD patients with hypothyroidism as compared to CKD patients without hypothyroidism. Additionally, we examined the relationship between irisin and insulin resistance, inflammation and body composition. Methods: It was a descriptive study conducted between November 2014 and October 2015 at Endocrinology and Nephrology department of a tertiary care center in South India -- JIPMER. In this study 200 non diabetic CKD patients not on maintenance hemodialysis were included. All patients underwent thyroid function testing and body fat analysis. Fasting serum irisin, insulin and c reactive protein were measured in 40 patients with thyroid dysfunction and 40 age, BMI, waist circumference and level of activity matched controls. HOMA-IR and QUICKI indices were calculated. Results: The prevalence of the hypothyroidism was 21.5%. The median age, BMI, and eGFR of the study population, were 52 years, 21.01 kg/ m2 and 23 ml/min/1.73 m2 respectively. The serum irisin levels were not significantly different between hypothyroid CKD and euthyroid CKD patients. The serum irisin levels had no correlation with thyroid function tests, renal function, and inflammatory marker. The serum irisin concentration (median) was higher in females 467.00 ng/ ml than in the males 54.00 ng/ml. The median serum irisin levels were significantly higher in subjects with low activity (99.50 ng/ ml) compared to those with moderate activity (34 ngl/ml) and high activity (28.50 ng/ml). In univariate analysis, irisin correlated with BMI, waist circumference, insulin indices, and fat mass indices. In multivariate analysis, the significant predictors of irisin were female gender and total fat mass. Conclusions: The regulation of irisin in CKD patients is probably multifactorial. The association with fat mass suggest that fat mass is a significant contributor to the circulating irisin in CKD patients. The gender dimorphism in irisin levels needs to be studied in further. [ABSTRACT FROM AUTHOR]