Study proposes CBC flag for sample interference in dogs: full analysis

A newly published canine haematology study is putting a niche analyser metric into more practical clinical use. In the Journal of Small Animal Practice, investigators from the University of Bologna report that the gap between mean corpuscular haemoglobin concentration and mean cellular haemoglobin concentration, or ΔMCHC-CHCM, can help identify when a canine CBC may be distorted by sample artefact or certain endocrine-related clinical contexts. Using the Siemens ADVIA 2120, the team recommends that results above 2.5 g/dL should prompt further diagnostic evaluation. (pubmed.ncbi.nlm.nih.gov)

The distinction matters because these two values are generated differently by ADVIA technology. MCHC is a calculated index familiar to most clinicians, while CHCM is a cell-based measurement produced by the analyser’s optical methods. That gives the difference between them potential value as an internal check when the CBC and the sample don’t quite fit together. Veterinary diagnostic laboratories using the ADVIA 2120 already publish species-specific reference intervals for analyser-derived haematology variables, but this study adds evidence for how one less commonly discussed parameter might be applied in day-to-day case interpretation. (vet.cornell.edu)

According to the abstract, the study had three aims: establish a reference interval for ΔMCHC-CHCM in healthy dogs, identify causes of increased values in healthy and diseased canine samples, and define a threshold that should prompt follow-up by practitioners. The authors used a retrospective review of dogs seen at a veterinary teaching hospital and prospectively enrolled healthy dogs for reference interval work. CBCs were run within two hours of collection, biochemistry within 12 hours, and the team also recorded macroscopic sample alterations including haemolysis, icterus, and lipaemia. (pubmed.ncbi.nlm.nih.gov)

Their key finding was that the reference interval for ΔMCHC-CHCM ranged from -1.70 to 2.20 g/dL, with the 90% confidence interval for the upper limit extending to 2.50 g/dL. Increased values were significantly associated with lipaemic and haemolytic samples, and the metric rose with the severity of those alterations. Samples at or above 2.5 g/dL were also significantly more common in dogs receiving corticosteroid therapy or affected by Cushing’s syndrome. In practical terms, the authors conclude that a value above 2.5 g/dL should lead laboratorians and clinicians to look carefully for haemolysis, lipaemia, or both before over-interpreting the rest of the CBC. (pubmed.ncbi.nlm.nih.gov)

Direct outside commentary on this specific paper appears limited so far, but the findings fit with established clinical pathology principles. Automated haematology systems can generate spurious or misleading erythrocyte and leukocyte values when samples are affected by artefact or interfering substances, and smear review remains an important safeguard. A prior feline study from overlapping authors similarly showed that analyser-derived discrepancies can flag interference, in that case from Heinz bodies, underscoring a broader theme: advanced analyser outputs can be clinically useful, but only when paired with expert review. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, this paper is less about introducing a brand-new disease marker than about sharpening laboratory judgment. If a dog’s CBC shows an unexpectedly high MCHC, ΔMCHC-CHCM may help distinguish between true biological change and preanalytical or analytical interference. That’s especially relevant in referral and emergency settings, where lipaemia, in vitro haemolysis, endocrine disease, and steroid exposure are all common confounders. The association with corticosteroid treatment and Cushing’s syndrome is also notable because current guidance already places CBC, chemistry, and urinalysis at the center of hypercortisolism workups; this parameter may offer one more clue that the laboratory picture needs careful context. (pubmed.ncbi.nlm.nih.gov)

The study’s applicability is also somewhat platform-specific. CHCM is an ADVIA-generated measurement, so the proposed threshold should not be assumed to transfer directly to other in-clinic or reference-lab analysers that calculate or measure red cell haemoglobin indices differently. Even so, the paper may encourage more laboratories to expose or comment on this delta value in reports, especially where ADVIA instruments are already in use. That could improve communication with clinicians and help prevent unnecessary follow-up on artefactual abnormalities. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next question is whether other groups validate the >2.5 g/dL cut-off in broader canine populations, assess its performance prospectively, or test whether similar “delta” flags can be standardized across analyser platforms. For now, the most immediate impact is likely to be in clinical pathology workflows: more deliberate review of sample quality, medication history, and endocrine differentials when this gap is elevated on an ADVIA canine CBC. (pubmed.ncbi.nlm.nih.gov)