Abstract

Lipocalin level and indicators of lipid metabolism in the initial stages of chronic kidney disease against the background of obesity

Author(s): Nataliia Vasylivna Gubina, Iryna Hryhorivna Kupnovytska, Nelia Mikolaivna Romanyshin and Vasyl Hryhorovych Mishchuk

Introduction: In recent decades, the number of patients with chronic kidney disease (CKD) and obesity has increased. The pathological cascade that combines these pathologies is characterized by an imbalance of adipokines, a change in metabolic homeostasis indicators, in particular, a violation of lipid metabolism, and low intensity inflammation. Neutrophil gelatinase-associated lipocalin (NGAL, lipocalin-2) is a small protein purified from neutrophil granules and can serve as a biomarker of kidney pathology against the background of obesity formation.

The purpose is to evaluate changes in lipocalin-2 level as a marker of early diagnosis of damage to the renal tubular apparatus and its relationship with individual indicators of lipid metabolism in patients with the initial stages of CKD against the background of obesity.

Materials and methods: 304 patients with chronic kidney disease (134 women and 170 men) and 30 practically healthy persons were examined. Patients were divided into 2 groups: the first group consisted of 148 patients with stage 1 of CKD and obesity and the second group consisted of 156 patients with stage 2 of CKD and obesity. All patients underwent general clinical examinations, determination of body mass index, indicators of glomerular filtration rate, microalbuminuria, and determination of lipocalin in urine and lipid panel indicators. Statistical processing of the obtained results was carried out using the Statistica 10.0 statistical analysis program.

Results: The increase of NGAL excretion with urine was greater in patients of the second group with an increased body mass index. An increase in NGAL level in urine was found to be a significant predictor of albuminuria, especially among patients of the second group. Calculated according to the CKD-EPIcysC/cr formula, GFR indicates a 1.5-fold decrease (p<0.001) of this indicator in patients of the second group compared to the first group, which confirms the impairment of kidney function, despite normal creatinine values. A direct correlation of medium strength was established between NGAL and BMI in both groups - r1=0.45, r2=0.58, respectively (p1.2<0.05), between NGAL and microalbuminuria - r1=0.45, r2 =0.48, respectively (p1.2<0.05). In patients of the second group, a direct correlation of average strength was found between the indicator of daily albuminuria and BMI (r=0.56, p<0.05), and an inverse correlation of average strength between NGAL and GFR (CKD-EPIcysC/cr) - r2= - 0.53. A weak positive correlation was established between microalbuminuria and triglyceride levels in patients of group 2 (r2=0.3, p>0.05). Analysing correlations between NGAL and specific indicators of lipid metabolism, there was no reliable relationship between the level of lipocalin and general cholesterol as well as between lipocalin and high- and low-density lipoproteins. Instead, a positive correlation was observed between NGAL and triglyceride levels in patients of group 2 (r2= 0.51, p<0.05).

Conclusion: Thus, the study of changes in the level of lipocalin-2 in the early stages of CKD, which developed against the background of obesity, can serve as a marker of damage to the tubular apparatus, as indicated by the average inverse correlation between the glomerular filtration rate and the direct correlation between lipocalin and microalbuminuria. Also, in the early stages of CKD against the background of obesity, there is a lipid metabolism imbalance – an increase of general cholesterol, triglycerides, low-density lipoprotein levels, and a decrease of high-density lipoprotein levels. Dyslipidemia, which develops in the early stages of CKD and is associated with obesity, probably increases the progression of renal tissue damage and is a risk factor for cardiovascular events.