A Comprehensive Analysis of Serum and Urine Bile Acid Profiles in Chronic Kidney Disease: An Exploratory Study of Clinical Associations.

Total serum bile acid levels did not differ significantly between CKD and normal renal function groups.

• Cross-sectional study with 29 patients with advanced CKD and 30 sex- and age-matched individuals with normal renal function (NRF)
• Despite differences in individual bile acid fractions, overall total serum bile acid concentrations were comparable between groups
• This finding suggests redistribution rather than overall accumulation of bile acids in CKD

Patients with CKD had lower serum levels of unconjugated bile acids compared to those with normal renal function.

• Study population consisted of 29 advanced CKD patients and 30 age- and sex-matched controls with normal renal function
• Unconjugated bile acid fractions were specifically reduced in the CKD group
• This finding suggests altered gut microbial deconjugation activity or altered enterohepatic circulation in CKD

Patients with CKD exhibited significantly higher serum levels of sulfate-conjugated bile acids than those with normal renal function.

• Sulfate-conjugated bile acids were significantly elevated in the serum of CKD patients compared to NRF controls
• The 29 CKD patients were matched with 30 NRF individuals by sex and age
• Elevated sulfate-conjugated bile acids may reflect compensatory renal or hepatic sulfation in the context of impaired kidney excretion

Urinary total bile acid levels and most bile acid subgroups were significantly lower in patients with CKD compared to normal renal function controls.

• Both total urinary bile acids and most individual bile acid subgroups showed significant reductions in the CKD group
• Reduced urinary bile acid excretion is consistent with decreased glomerular filtration capacity in advanced CKD
• This contrasts with the serum findings, where sulfate-conjugated forms were elevated, suggesting impaired renal clearance

Serum levels of ursodeoxycholic acid, chenodeoxycholic acid, and sulfate-conjugated bile acids were associated with decline in estimated glomerular filtration rate.

• These associations remained significant even after adjusting for demographic factors and diabetes status
• The analysis was conducted in the full study cohort of 29 CKD patients and 30 NRF controls
• Ursodeoxycholic acid and chenodeoxycholic acid are secondary and primary bile acids respectively, suggesting both microbial and hepatic bile acid metabolism are implicated in CKD progression
• The adjusted associations highlight the independent relationship between specific bile acid species and kidney function decline

Dysbiosis and gut microbiota-derived metabolites, including bile acids, are implicated in the pathophysiology of CKD progression to end-stage kidney disease.

• Bile acids are described as 'key metabolic products of the gut microbiota'
• The role of bile acids in CKD pathophysiology was previously 'incompletely understood' prior to this study
• Profiling bile acid metabolism is suggested to 'provide valuable insights into CKD pathophysiology and help in identifying novel therapeutic targets'