Molecular composition of adiponectin in urine is a useful biomarker for detecting early stage of diabetic kidney disease.

We previously developed two immune complex transfer enzyme immunoassays (ICT-EIA) to measure total adiponectin (T-AN) and high molecular weight adiponectin (H-AN) in urine and have verified their usefulness as biomarkers for diabetic kidney disease. In this study, we developed T-AN and H-AN assays using the sandwich EIA (Sand-EIA). The reactivities of Sand-EIAs were compared with ICT-EIAs by measuring size exclusion chromatography (SEC) fractions of urine and adiponectin standard. As a result, ICT-EIAs showed higher macromolecular specificity. We then analyzed the molecular profile of adiponectin in the urine of 5 patients with different eGFR stages by measuring SEC fractions of urine. The results showed that smaller adiponectin correlated relatively well with eGFR stage. Finally, because SEC is time-consuming, we investigated that the ratio of T-ANs by Sand-EIA and ICT-EIA could be a good indicator of the monomer adiponectin. The ratio was evaluated using 77 urine samples from patients with diabetes and showed a significant decrease at an earlier stage compared with other biomarkers. In conclusion, we demonstrated a new index to estimate monomer adiponectin in urine by using Sand-EIA and ICT-EIA, and urinary monomer adiponectin can be a good early indicator of deterioration of renal function in diabetic patients. J. Med. Invest. 70 : 464-470, August, 2023.

Comparison of urinary adiponectin in the presence of metabolic syndrome in peri- and postmenopausal women.

OBJECTIVES: To find the association between urinary adiponectin and metabolic syndrome (MetS) in peri- and postmenopausal women and its potential application as a noninvasive screening for MetS. METHODS: A cross-sectional study was conducted in healthy peri- and postmenopausal women (defined by STRAW + 10 staging) aged at least 40 years who attended annual check-ups or menopause clinics were recruited. Baseline demographic data, MENQOL, anthropometric measurements, blood pressure, laboratory (FBS, total cholesterol, HDL-C, LDL-C, TG), and urinary adiponectin were collected. The MetS was diagnosed according to JIS 2009. RESULTS: 290 peri- and postmenopausal women had participated. The prevalence of Mets among our participants was 18%. Urinary adiponectin levels were similar in peri- and postmenopausal women with and without MetS (2.6 ± 2.2 vs. 2.3 ± 1.9 ng/mL, respectively, P = 0.55). Urinary adiponectin provides no diagnostic value for MetS (AUC = 0.516). CONCLUSIONS: Urinary adiponectin has no role in screening and diagnosing MetS in peri- and postmenopausal women. The quest toward noninvasive screening for MetS is still going on.

Urinary adiponectin excretion is an early predictive marker of the decline of the renal function in patients with diabetes mellitus.

AIMS: Since diabetes-associated kidney complication changes from diabetic nephropathy to diabetic kidney disease (DKD), more suitable biomarkers than urinary albumin are required. It has been hypothesized that urinary adiponectin (u-ADPN) is associated with the progression of DKD. We therefore evaluated the effectiveness of u-ADPN in predicting the decline of the renal function in patients with diabetes prior to end-stage renal disease. METHODS: An ultrasensitive immune complex transfer enzyme immunoassay (ICT-EIA) was used to measure total and high molecular weight (HMW) adiponectin separately. We evaluated the relationships between the creatinine-adjusted urinary total-ADPN and HMW-ADPN, albumin (UACR) and liver-type fatty acid binding protein (L-FABP) at baseline and the 2-year change of the estimated glomerular filtration rate (ΔeGFR). RESULTS: This 2-year prospective observational study included 201 patients with diabetes. These patients were divided into three groups according to their ΔeGFR: ≤-10 mL/min/1.73m2, >-10 and ≤0 mL/min/1.73m2, and >0 mL/min/1.73m2. Jonckheere-Terpstra test showed that lower ΔeGFR was associated with higher u-HMW-ADPN (p = 0.045). In logistic regression analysis, u-HMW-ADPN was associated with ΔeGFR after adjusted age, sex, and basal eGFR. CONCLUSION: Urinary HMW-ADPN could predict a declining renal function in patients with diabetes.

Increased urinary adiponectin level is associated with contrast-induced nephropathy in patients undergoing elective percutaneous coronary intervention.

BACKGROUND: Contrast-induced nephropathy (CIN) is one of major and serious complications in patients undergoing percutaneous coronary intervention (PCI). It is unknown whether increased urinary adiponectin (UAPN), a sensitive marker for early renal function impairment, is associated with an increased risk of CIN. Therefore, we prospectively investigate the association of UAPN with CIN. METHODS: We prospectively enrolled 208 patients who were undergoing elective PCI. The baseline UAPN was assessed prior to PCI. The ROC analysis was used to evaluate the predictive value of UAPN for CIN. Multivariate logistic regression analysis was performed to analyze the independent risk factors for CIN. RESULTS: Of 208 patients, CIN occurred in 19 patients (9.13%), and 6 of them (2.88%) required dialysis. Patients with CIN had a higher UAPN level than those without CIN (17.15 ± 12.36 vs. 10.29 ± 3.04 ng/ml, P < 0.01). ROC analysis showed that the optimal cutoff value of UAPN for predicting CIN was 12.24 ng/ml with 68.42% sensitivity and 76.72% specificity (AUC = 0.7204; 95% CI, 0.582-0.859; 푃< 0.01). Multivariate analysis demonstrated that UAPN (OR, 5.071; 95% CI,1.711-15.028; P < 0.01) and serum creatinine (Scr) > 124 µmol/L (OR, 4.210; 95% CI, 1.297-13.669; P < 0.01) were independently associated with CIN. CONCLUSIONS: Our present study showed that a higher baseline UAPN (≥12.24 ng/ml) level was significantly associated with an increased risk for developing CIN post PCI.