1. The effects of age and sex on reference intervals for cobalamin, homocysteine, and serum and urinary methylmalonic acid in healthy adult dogs
- Author
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Anna‐Lena Proksch, Sophia Schaefer, Vanessa Dreller, Judith Langenstein, Ralph Fingerhut, Natali Bauer, and Andreas Moritz
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B12 metabolism ,canine ,serum ,sex ,urine ,vitamin B12 ,Veterinary medicine ,SF600-1100 - Abstract
Abstract Background In dogs, data on reference intervals (RIs) for cobalamin, markers of metabolism (markersB12met), age and sex effects are limited. Hypothesis/Objectives Establish RI for serum cobalamin, homocysteine, and methylmalonic acid (sMMA) concentrations, urinary methylmalonic acid‐to‐creatinine ratio (uMMA:crea), and determine effects of sex and age. Methods Prospective study using healthy dogs (1‐10 years). Cobalamin and markersB12met were determined using chemiluminescence immunoassay (cobalamin) and liquid chromatography/tandem mass spectrometry (homocysteine, sMMA, uMMA:crea). In dogs with outlying data, changes in health, markersB12met, and onset of gastrointestinal signs were reevaluated after 9‐15 months. Results Twelve of 120 healthy dogs had abnormal uMMA:crea ratios. No other cobalamin analyte outliers were found. Outlying data re‐examination (odRE) was performed in 10/12 dogs. Chronic gastrointestinal signs occurred in 64% of odRE‐dogs, whereas 36% remained healthy. In total, 112 dogs (67 females, 45 males; median ages, 3.5 and 3.75 years, respectively) were included in RI analyses. Reference intervals were 178.5‐851 pmol/L (cobalamin), 5.8‐29.0 μmol/L (homocysteine), 45.3‐159.5 μg/L (sMMA), and ≤22.4 mg/g (uMMA:crea). Only age affected cobalamin concentrations (significant decrease). Compared by sex and neuter status, intact male dogs had significantly higher uMMA:crea ratios (median, 13.5; range, 1.9‐83.6 mg/g) than the other groups (median, 2.5; range, 0.7‐9.7 mg/g; P
- Published
- 2025
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