Blood-panel patterns across feline creatinine strata and shared baseline effects on ratio associations

Cats with similar creatinine (CRE) values can have different accompanying blood-panel findings, but the relevance of these patterns to subsequent change is uncertain.

We examined routine blood panels across seven clinically proposed creatinine strata, refined through retrospective review. The dataset comprised 5,743 episode-anchored visits from 3,006 cats; chronic kidney disease (CKD) diagnoses were unavailable. A broad candidate review yielded 33 calculable markers for screening.

The ratios of blood urea nitrogen (BUN), phosphorus (PHOS), and symmetric dimethylarginine (SDMA) to CRE met false-discovery-rate correction for association with creatinine slopes that included the baseline visit. None met correction for slopes using subsequent visits only. Removing the baseline visit reduced absolute correlations more for these three ratios than for 27 other nonredundant markers (mean difference 0.120; cat-cluster bootstrap 95% CI 0.038-0.198), consistent with shared-baseline coupling. In post hoc analyses of strata 1-2, PHOS/CRE and SDMA/CRE associations remained positive after adjustment for age and baseline creatinine, but did not meet correction (both q = 0.072). Component models did not show consistent added value from either ratio. The BUN-to-albumin (ALB) ratio mainly reflected current values and within-episode changes. Serum amyloid A (SAA), the neutrophil (NEU)-to-lymphocyte (LYM) ratio, and the ALB-to-globulin (GLOB) ratio described systemic patterns weakly associated with creatinine.

Clinical observations and retrospective data supported considering accompanying systemic and electrolyte findings when assessing individual cats. Whether interpreting these findings together improves clinical assessment requires prospective validation.