{"doi":"10.1093/jalm/jfaf075","title":"Creatinine Delta: Improving Critical Call Thresholds for Acute Kidney Injury Detection","abstract":"To the Editor: Acute kidney injury (AKI) is a rapid decline in kidney function with or without structural kidney damage, occurs in around 25% of patients admitted to hospitals and over 50% of patients receiving critical care (1). According to the American Association for Clinical Chemistry-AKI 2020 criteria, an increase of 0.2 mg/dL or 20% (whichever is greater) in serum creatinine is highly significant and may indicate AKI (2). Early detection of AKI is essential to preserve kidney function and reduce overall morbidity and mortality. In a 2017 survey on ADLM Artery (n = 26 hospitals), 15 reported not having a critical value threshold for creatinine, while the remaining facilities mainly used fixed thresholds (e.g., >5 mg/dL). The problem with such fixed thresholds is the constant unnecessary flagging of known patients with chronic kidney disease that fluctuate around the cutoff. More importantly, using a static cutoff (especially at such high thresholds) is not effective at detecting a critical component of AKI: significant increases in creatinine from baseline occurring below the cutoff point (i.e.,<5 mg/dL) (3). In this study, we aimed to evaluate the feasibility and utility of a more specific critical threshold for creatinine that is based on large changes from a patient's baseline (delta creatinine, e.g., +1.5 mg/dL), rather than a single fixed cutoff (e.g., >5 mg/dL) to minimize false positives. We hypothesized that this approach would reduce unnecessary calls by laboratory personnel and alleviate frustration among clinical teams receiving calls they consider unnecessary. We proposed a new “creatinine delta” critical result that has 2 thresholds: (a) an increase in creatinine (delta creatinine) of >1.5 mg/dL in baseline creatinine concentrations of <1.5 mg/dL and (b) an increase of >3 mg/dL for baseline creatinine concentrations of 1.5 to 5 mg/dL. The lookback period for a baseline creatinine was set to 1 year to trigger a delta calculation, and the most recent creatinine result in the system was used. These criteria were designed to be specific to large changes in creatinine with a lookback period that accounts for known biological variation (2). All samples were run on Roche Cobas 8000 (Roche Diagnostics). Patient creatinine results were retrospectively retrieved from Yale-New Haven Hospital’s database for all creatinine that would have flagged in a 12-month period (September 2023–August 2024). This quality improvement study was designated “not research” by Yale’s Institutional Review Board (ID# 2000039524). A single cutoff rule of >5 mg/dL would have triggered 5309 calls per year across our health system, while applying the proposed delta thresholds (>+1.5 mg/dL and >+3 mg/dL) would have reduced that number to 1623 calls. To assess the utility of these calls, we randomly selected 10 patients from each dataset: the >5 mg/dL rule, the >+1.5 mg/dL rule, and the >+3 mg/dL rule, totaling 30 cases. Medical charts for these patients were independently reviewed by 2 board-certified nephrologists and one emergency medicine physician to determine whether the calls would have been useful (Fig. 1). There was strong interrater agreement regarding which calls were useful. Patients with chronic kidney disease, particularly those on dialysis, were most often flagged as “nonuseful” calls. Creatinine delta rule proved more effective than the single 5 mg/dL cutoff, with 76.6% of calls deemed useful under the new delta creatinine criteria, compared to just 30% under the fixed threshold. Percent of critical calls deemed useful based on a single threshold SCr >5 mg/dL vs using delta SCr (average of increase of 1.5 mg/dL, if baseline <1.5 mg/dL, or increase of 3 mg/dL, if baseline 1.5–5 mg/dL) after medical chart review of 30 random patients by 2 nephrologists and one emergency department physician. Abbreviation: SCr, serum creatinine. While the study presents promising findings, limitations include: the small sample size (n = 3 physicians,","journal":"The Journal of Applied Laboratory Medicine","year":2025,"id":525842,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":3,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.962,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1052869,"name":"Rohit B. Sangal","orcid":"0000-0002-0435-7029","position":1,"is_corresponding":false},{"id":905045,"name":"Aldo J. Peixoto","orcid":"0000-0003-1525-2991","position":2,"is_corresponding":false},{"id":258520,"name":"Dennis G. Moledina","orcid":"0000-0002-9537-9038","position":3,"is_corresponding":false},{"id":1401365,"name":"Dustin Miconi","orcid":null,"position":4,"is_corresponding":false},{"id":406757,"name":"Joe M El-Khoury","orcid":"0000-0002-9444-9540","position":5,"is_corresponding":false},{"id":1386551,"name":"Jillian Kodger","orcid":null,"position":0,"is_corresponding":true}],"reference_count":5,"raw_metadata":null,"created_at":"2026-07-19T02:50:25.860105Z","pmid":"40424188","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}