Plasma homocysteine concentration in privately owned healthy adult cats: assessment of biological determinants and establishment of a reference interval

Objectives The assessment of homocysteine status in diseased cats has indicated high plasma concentrations in chronic kidney disease and yielded conflicting results with respect to cardiovascular disorders. Previous investigations in small populations of normal cats revealed greater-than-expected variability in plasma homocysteine concentration. The purpose of this study was to determine biological determinants and the reference interval (RI) of plasma homocysteine concentration in the feline species, under strict pre-analytical conditions. Methods In this prospective observational study, privately owned healthy adult cats underwent a complete physical examination, urinalysis and blood testing, in order to rule out any signs of disease. Plasma homocysteine concentration was measured using high-performance liquid chromatography–tandem mass spectrometry. Results Of 151 cats recruited, 30 cats were not included owing to abnormal physical examination or fractious behaviour, and 30 cats were excluded based on abnormalities on blood work or urinalysis. Plasma homocysteine concentrations >28 µmol/l were associated with a dietary protein content >9.3 g/100 kcal metabolisable energy. The RI for plasma homocysteine concentration was determined to be 6.2–52.3 µmol/l. Conclusions and relevance Normal values for plasma homocysteine concentration in cats have a wide RI, suggesting high inter-individual variability. Whether some healthy cats exhibit impaired homocysteine metabolism remains to be elucidated.

Correlation between Behavioural and Psychological Symptoms of Alzheimer Type Dementia and Plasma Homocysteine Concentration

The relationship between plasma homocysteine and behavioral and psychological symptoms of dementia (BPSD) has not been specifically investigated in previous research. In this study, we compared plasma homocysteine (Hcy) among 40 Alzheimer’s disease (AD) patients with BPSD, 37 AD patients without BPSD, and 39 healthy controls. Our results evidenced that the plasma homocysteine levels in AD patients with BPSD and without BPSD were higher than healthy controls and that the plasma homocysteine concentration in AD patients with BPSD was the highest among the three groups. Significant correlation between plasma homocysteine concentration and cognitive decline and duration of dementia was observed, but there was no correlation between BPSD and cognitive dysfunction or duration of dementia. In conclusion, this study showed for the first time that BPSD were associated with plasma homocysteine concentration in Alzheimer's dementia, and the results supported that hyperhomocysteine may take part in the pathogenesis of BPSD.