Hyperhomocysteinaemia and poor vitamin B status in chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) are at increased atherothrombotic risk. Preliminary findings have suggested that COPD patients may have increased plasma total homocysteine (tHcy), a cardiovascular risk factor often caused by a poor B vitamin status, but plasma levels of such vitamins were not measured. The aim of this study was to investigate hyperhomocysteinaemia in COPD and to determine whether it may be secondary to poor plasma concentrations of B vitamins.

We performed a case-control, cross-sectional study of 42 patients with COPD and 29 control subjects. Folate, vitamin B12, vitamin B6, tHcy, renal function, C-reactive protein, blood gases and lipids were measured in patients and controls. COPD patients had higher plasma tHcy (median: 13.9mumol/l, interquantile range [IQR]: 12.1-18.5 versus 11.5, IQR: 10.1-14, p=0.002) and lower circulating folate (median: 2.5ng/ml, IQR: 1.2-3.3 versus 2.8, IQR: 2.1-4 of controls, p=0.03) than controls had. Compared to the control group, COPD was associated with higher tHcy concentrations also after adjusting for smoking, heart failure, renal function and C-reactive protein with logistic regression analysis (OR 1.36, 95% CI 1.06-1.72, p=0.01). In the COPD group, low levels of folate (beta=-0.27, p=0.02) and vitamin B12 (beta=-0.24, p=0.04), and hypertriglyceridaemia (beta=0.580, p<0.0001) were independent predictors of the presence of high tHcy concentrations in a multiple linear regression model (adjusted R(2)=0.522).

COPD patients have a poor B vitamin status and, as a consequence, increased tHcy. These abnormalities may contribute to the COPD-related atherothrombotic risk.