PFLPhysiological Fitness Landscape

Biomarkers · Renal & Purine

Blood Urea Nitrogen (BUN)

Lower values go with lower risk of death. In NHANES 1999–2018 with linked mortality to 2019, each standard deviation above average goes with 18% higher risk of death. We found the same pattern in NHANES

BUN and risk of death

NHANES, our fit with 95% CIPublished curve

Published curve higher than the NHANES fitNHANES fit higher

Risk of death relative to each curve's own reference value, so the two curves need not cross 1 at the same point. The dotted vertical line marks the NHANES median.

Risk of death per SD (NHANES)1.18×95% CI 1.15–1.20 · 48,361 adults, 7,025 deaths
Published risk of death1.48×higher BUN levels vs lower levels (highest vs lowest category) (95% CI 1.28–1.72) · NHANES 1999-2006 US adults, mortality linkage through 31 December 2015
Value of the measurement+0.032gain in concordance within age bands; rank 8 of 56 · all tests

BUN by age and sex

Each bar runs from the 5th to the 95th percentile, the darker part from the 25th to the 75th, and the tick is the median. Not a reference range or a target.

The percentiles as a table
Each row is one sex and age band: the values below which 5%, 25%, 50%, 75% and 95% of people fall (mg/dL), from the survey named in the row. Not a reference range or a target.
SexAge5th25thMedian75th95thnCycle / source
All20-398.0010.013.015.020.01,429NHANES 2017-2018
All40-598.0012.014.017.022.01,548NHANES 2017-2018
All60+10.014.017.021.030.01,890NHANES 2017-2018
Allall8.0011.814.018.024.04,867NHANES 2017-2018
Men20-398.0012.014.016.021.0684NHANES 2017-2018
Men40-599.0013.015.018.023.0723NHANES 2017-2018
Men60+10.014.217.021.028.0958NHANES 2017-2018
Menall9.0013.015.018.024.02,365NHANES 2017-2018
Women20-397.0010.011.014.017.8745NHANES 2017-2018
Women40-597.0010.013.016.020.0825NHANES 2017-2018
Women60+9.0014.017.021.030.0932NHANES 2017-2018
Womenall8.0011.013.017.023.02,502NHANES 2017-2018

What studies found when this marker was changed

They describe what happened in those study groups, not a recommendation. See all catalogued interventions.

Measured changes in BUN, study by study

2 effects with a numeric size, each from one study arm: the dot is the reported change, the line its 95% interval where one was given. Green points move the marker the way lower risk of death lies; amber the other way. Study results in the groups studied, not predictions for a person.

Each row is one study: what was changed, the effect it reported on this marker, and the source.
TypeInterventionReported effectEvidenceSource
dietStructured dietary protein restriction (low-protein diet) in CKDLow-protein diets decreased blood urea nitrogen in CKD (low-certainty evidence; effect size not reported)systematic reviewAmiri Khosroshahi R, et al. Effects of a Low-Protein Diet on Kidney Function in…
lifestyleOptimal fluid intake (2-3 L/night during daytime fasting)Higher fluid intake (2 to 3 L overnight) kept serum urea significantly lower than controls during fasting (P <.05; effect size not reported)RCTTarabeih M, et al. Increasing Overnight Fluid Intake and Kidney Function During…

Things that worsen it

Each row is one study: what was changed, the effect it reported on this marker, and the source.
TypeCondition or exposureReported effectEvidenceSource
clinicalUpper gastrointestinal bleedingBUN/Cr ratio higher in upper vs lower GI bleeding (pooled mean difference 11.44, 95% CI 8.35-14.52); ratio > 30 specificity 89.3%meta-analysisSimadibrata DM, et al. Blood Urea Nitrogen-to-Creatinine Ratio to Differentiate…
dietLow-carbohydrate high-protein weight-loss dietSerum urea higher vs low-fat diet by 14.4% at 3 months, 9.0% at 12 and 8.2% at 24 monthsRCTFriedman AN, et al. Comparative effects of low-carbohydrate high-protein versus…

What else moves this marker

They describe those study groups, not an individual, and an association is not a cause.

Genetic predisposition

Each row is one study: what it compared and the change it reported in this marker.
WhatEffect on the markerComparison · populationSource
↑ Genetically predicted BMI (Mendelian randomization), per 1 SD · Per 1 SD (~4.8 kg/m2) genetically higher BMI; beta 0.010 log(BUN)+1% (95% CI 0.5 to 1.5)Per 1 SD higher genetically predicted BMI (beta 0.010 log BUN, 95% CI 0.005-0.015, converted exp(beta)-1) · Two-sample MR, European ancestry (GIANT, DIAGRAM, CKDGen summary data)mendelian randomization · PMID 34922334

Sources

Map Blood Urea Nitrogen (BUN) against another biomarker.

Related markers: Alpha-1-Microglobulin · Beta-2 Microglobulin · Beta-Trace Protein (BTP) · Estimated Glomerular Filtration Rate (eGFR) · Kidney Injury Molecule-1 (KIM-1) · Neutrophil Gelatinase-Associated Lipocalin (NGAL) · Renal Artery Calcification · Serum Creatinine

Map BUN against another marker