Relationship of serum bilirubin concentrations to kidney function and albuminuria in the United States adult population. Findings from the National Health and Nutrition Examination Survey 2001–2006

Background: The association of serum bilirubin concentrations with kidney function and albuminuria has not been established in the US general population. Methods: We performed a cross-sectional analysis of data from the National Health and Nutrition Examination Survey (NHANES) 2001–2006 and examined the associations of serum total bilirubin concentrations with estimated glomerular filtration rate (eGFR) and albuminuria in a nationally representative sample of 13,184 adults aged 20 years or older. eGFR was estimated using the abbreviated Modification of Diet in Renal Disease equation. Urinary albumin excretion was measured using the albumin/creatinine ratio. Results: An eGFR <60 mL/min/1.73 m2 and urinary albumin/creatinine ratio ≥30 mg/g were present in 8.1% (n=1072) and 10.6% (n=1402) of participants, respectively. A total of 427 (3.2%) individuals had a serum total bilirubin concentration >22.23 μmol/L. After adjustment for demographics, comorbidities, alcohol consumption, viral hepatitis status and other laboratory measures, serum bilirubin was negatively associated with eGFR, and positively with albuminuria both in the whole cohort and in the subgroup of non-diabetic individuals. In contrast, serum bilirubin was not significantly associated with eGFR or albuminuria in persons with diabetes (n=1253). Conclusions: Increasing serum concentrations of total bilirubin are independently associated with decreasing eGFR and increasing albuminuria in the US adult population. Clin Chem Lab Med 2009;47:1055–62.Peer Reviewe

Parathyroid hormone and arterial dysfunction in the multi-ethnic study of atherosclerosis.

ObjectiveHigh circulating concentrations of parathyroid hormone (PTH) have been associated with increased risks of hypertension, left ventricular hypertrophy, congestive heart failure and cardiovascular mortality. Impaired arterial function is a potential mechanism for these associations. We tested whether serum PTH concentration is associated with measures of arterial function.DesignCross-sectional study.ParticipantsA total of 6545 persons without clinical cardiovascular disease participating in the community-based Multi-Ethnic Study of Atherosclerosis.MeasurementsBrachial artery flow-mediated dilation (FMD) as well as aortic pulse pressure and arterial pulse parameters derived from Windkessel modelling of the radial pressure waveform.ResultsHigher serum PTH concentration was associated with lower brachial artery FMD (mean difference -0·09% per 10 pg/ml PTH), higher aortic pulse pressure (0·53 mmHg per 10 pg/ml) and reduced Windkessel capacitive index C1 (large artery elasticity, -0·12 ml/mmHg × 10 per 10 pg/ml), adjusting for potential confounding variables (all P-values ≤ 0·001). These relationships were independent of serum calcium concentration, serum 25-hydroxyvitamin D concentration and estimated glomerular filtration rate and were consistent across relevant participant subgroups. Associations of PTH with aortic pulse pressure and capacitive index C1 were attenuated after adjustment for blood pressure. Serum PTH concentration was not associated with the oscillatory index C2 (small artery elasticity).ConclusionsHigher serum PTH concentration was associated with impaired endothelial function, increased aortic pulse pressure and decreased capacitive index C1 in a large, diverse, community-based population. These relationships may help explain previously observed associations of elevated PTH with cardiovascular disease