Advanced age is associated with an increase in postoperative morbidity and mortality in cardiac surgery patients. In detail, compared with younger patients those aged 75 years and older have significantly higher rates of in-hospital mortality, cerebrovascular events, pneumonia, and dialysis. In addition, older cardiac surgery patients have longer mechanical ventilation times. Vitamin D exerts several beneficial effects on the cardiovascular system. Moreover, it has immuno-modulatory and anti-inflammatory properties. The hormonal form of vitamin D, 1,25-dihydroxyvitamin D, is an independent predictor of mid-term mortality in cardiac transplant recipients. 1,25-dihydroxyvitamin D also predicts mid-term and long-term mortality in patients with a high risk for cardiovascular disease. Mild renal impairment, insufficient vitamin D levels, and secondary hyperparathyroidism are common in frail elderly individuals. The present study aimed to investigate whether cardiac surgery exerts age-dependent effects on calciotropic hormones, components of the immune system, and inflammatory processes.It is hypothesized that (i) baseline 1,25-dihydroxyvitamin D levels are lower in patients <= 75 years of age compared to younger patients, (ii) cardiac surgery results in a transient decrease in circulating 1,25-dihydroxyvitamin D, and (iii) that the decrease in 1,25-dihydroxyvitamin D is probably more pronounced in older than in younger cardiac surgery patients.

Inclusion Criteria:

• age: <= 65 years and >= 75 years
• first elective cardiac surgery (bypass or combined bypass and heart valve surgery)
• written informed consent

Exclusion Criteria:

• emergency cardiac intervention
• primary hyperparathyreoidism
• primary and secondary hypoparathyreoidism
• daily vitamin D supplementation > 10 micrograms

elective cardiac surgery patients receiving isolated coronary artery bypass grafting or combined coronary artery bypass grafting and heart valve surgery