Bobby V. Li¹, Amas K. H. Lee¹, Robert C. W. Hawkins¹

¹Department of Laboratory Medicine, Tan Tock Seng Hospital, Singapore, Singapore

Background: Measurand reference intervals (RI) may differ by ethnicity and/or geography. This study derived indirect RI for urea, electrolytes, and creatinine (UEC) in a multi-ethnic population in Singapore.

Methods: Results of unique adults attending the Health Enrichment Centre between July 2018-June 2024 were assessed (plasma samples analysed using Beckman Coulter AU5800). After latent abnormal value exclusion (LAVE: results outside existing lab RI for other measurands), central 95% RI were calculated using refineR with 95% confidence intervals (95%CI) for upper and lower reference limits by 200 bootstraps.

Results: The final dataset included 1104 men and 1425 women with median age 47 [IQR:38-56] years; Chinese 76.9%, Malay 2.2%, Indian 5.4%, Others 15.3%. RI (95% CI) were: Sodium: 136 (136-138)–143 (142-143) mmol/L; Potassium: 3.4 (3.4-3.4)–4.4 (4.3-4.4) mmol/L; Chloride: 101 (100-102)–107 (107-107) mmol/L; Creatinine (Jaffe): male: 63 (57-69)–96 (92-104) µmol/L, female: 43 (42-44)–71 (64-73) µmol/L; Urea: male: 3.0 (2.9-3.6)–6.6 (6.1-7.0) mmol/L, female: 2.4 (2.1-2.7)–6.4 (5.3-6.5) mmol/L.

Conclusions: Indirect UEC RI were established in a predominantly Chinese Asian population. Compared to Australasian data, female RI were lower for creatinine and urea. This highlights the need to customise RI to local populations.

The work presented was the presenting author's original idea.