BUN Test Terminology in Singapore
In Singapore, the BUN (Blood Urea Nitrogen) test is commonly referred to as "serum urea" or simply "urea," measured in mmol/L rather than mg/dL as used in the United States.
Understanding the Terminology Difference
- Singapore, like most countries following the International System of Units (SI), reports urea levels directly rather than as "blood urea nitrogen" 1
- The term "urea" refers to the actual molecule being measured, while BUN specifically measures the nitrogen component of urea 1
- When reviewing laboratory reports from Singapore, you will typically see "Urea" or "Serum Urea" listed, not "BUN" 2, 3
Unit Conversion
- Singapore uses mmol/L for urea measurement, while the US uses mg/dL for BUN
- To convert: BUN (mg/dL) ÷ 2.8 = Urea (mmol/L)
- Conversely: Urea (mmol/L) × 2.8 = BUN (mg/dL)
- This conversion factor is used in calculated serum osmolality formulas: cSosm = (2 × sodium) + (BUN/2.8) + (glucose/18) 4
Clinical Application
- Despite the naming difference, the clinical interpretation and significance remain identical—both measure nitrogenous waste products reflecting renal function and protein metabolism 1, 5
- Normal reference ranges in Singapore are typically 2.5-7.1 mmol/L for urea, which corresponds to approximately 7-20 mg/dL for BUN 6
- When communicating with Singaporean laboratories or reviewing reports, always specify whether you need results in mmol/L or mg/dL to avoid confusion 2, 3
Important Clinical Caveat
- Regardless of terminology, proper blood sampling technique remains critical—samples must be drawn without dilution from saline or heparin to ensure accurate measurements 7
- The clinical significance of elevated urea/BUN levels (assessment for pre-renal azotemia, intrinsic kidney disease, or post-renal obstruction) is identical regardless of which term or unit system is used 2, 6