bun_creatinine_ratio: BUN/Creatinine Ratio

In cliot: Clinical Indices and Outcomes Tools

BUN/Creatinine Ratio

Description

Calculates the Blood Urea Nitrogen (BUN) to Creatinine ratio. This ratio helps differentiate between prerenal, intrinsic renal, and postrenal causes of acute kidney injury (AKI). The calculation standardizes inputs to mg/dL before computing the ratio to ensure consistent application of the 10:1 and 20:1 clinical thresholds.

Usage

bun_creatinine_ratio(bun, creatinine, bun_units = "mg/dL", creatinine_units = "mg/dL")

Arguments

bun	Numeric. Blood Urea Nitrogen level.
creatinine	Numeric. Serum Creatinine level.
bun_units	String. Units for BUN input. Options: "mg/dL" (default) or "mmol/L" (Urea).
creatinine_units	String. Units for Creatinine input. Options: "mg/dL" (default), "umol/L", or "mmol/L".

Value

A list containing:

BUN_Creatinine_Ratio	The calculated dimensionless ratio (based on mg/dL values).
Interpretation	Clinical classification (Prerenal, Normal/Postrenal, Intrarenal).
Possible_Causes	List of potential etiologies associated with the ratio range.

References

Dossetor JB. Creatininemia versus uremia. The relative significance of blood urea nitrogen and serum creatinine concentrations in azotemia. Ann Intern Med. 1966;65(6):1287-1299. doi:10.7326/0003-4819-65-6-1287

Examples

# Example 1: Prerenal Azotemia (Dehydration)
# BUN 40 mg/dL, Cr 1.0 mg/dL
# Ratio = 40 (>20)
bun_creatinine_ratio(40, 1.0)

# Example 2: Intrinsic Renal Disease (ATN)
# Urea 10 mmol/L, Cr 300 umol/L
# BUN = 10 * 2.8 = 28 mg/dL
# Cr = 300 / 88.4 = 3.39 mg/dL
# Ratio = 28 / 3.39 = 8.2 (<10)
bun_creatinine_ratio(10, 300, "mmol/L", "umol/L")

cliot documentation built on Dec. 1, 2025, 1:06 a.m.