Recommended ‘starter’ alert thresholds for a selection of chemical pathology tests

The RCPA-AACB High Risk Results Working Party has employed an evidence and risk based approach to identify alert thresholds for a selection of chemical pathology tests.1 A systematic literature review training program was conducted by the Australian Institute of Health Innovation at Macquarie University, which produced outcome study evidence for the mortality risk associated with seven chemistry blood tests. For each of these tests, the working party gathered information on: (A) clinical management of patients with abnormal results, (B) current professional recommendations for alert thresholds, (C) transferability of test results that were measured by different analytical methods, (D) laboratory flagging rates for a range of candidate alert thresholds. The above evidence was evaluated, and the following alert thresholds were identified: Ammonia >150 umol/L (neonate) or >100 umol/L (infant/child/adult); Adjusted Calcium <1.80 mmol/L and >3.20 mmol/L; Delta Creatinine rise >150 umol/L (adult) or >50 umol/L (paediatric); Absolute Creatinine >350 umol/L (adult) or >100 umol/L (paediatric); Glucose <2.5 mmol/L, and >15.0 mmol/L (paediatric) or >15.0 mmol/L with bicarbonate ≤15 mmol/L (adult) or >30.0 mmol/L with bicarbonate >15 mmol/L (adult); Lactate ≥4.0 mmol/L; Magnesium <0.40 mmol/L and >2.00 mmol/L; Sodium <120 mmol/L and >15 5mmol/L. Laboratories should assess the recommended thresholds with respect to their local population, and consult with key clinical users of their laboratory service for fine tuning as required. Reference 1. Campbell CA, Lam Q, Horvath AR. An evidence- and risk-based approach to a harmonized laboratory alert list in Australia and New Zealand. Clin Chem Lab Med 2018; 57: 89–94.