Обмен кальция и остеопороз у больных ишемической болезнью сердца в пожилом и старческом возрасте

Abstract

im. To analyze the relationship between calcium and various clinical and laboratory parameters in old and very old patients with coronary artery disease (CAD) based on the determination of the blood concentration of ionized calcium and daily excretion of calcium in the urine. Materials and methods. This work was a cross-sectional study enrolled 102 patients (84 women and 18 men) with coronary artery disease with a mean age of 83.0±5.9 years. The blood level of ionized calcium (N 1.16–1.32 mmol/l), daily excretion of calcium in the urine (N 2.5– 7.5 mmol/l) and concentration of 25-hydroxycalciferol (25(OH)D) were determined in all patients. Along with this, the bone mineral density of the lumbar spine and proximal femur was analyzed using dual-energy x-ray absorptiometry. Results. The mean daily excretion of calcium in the urine was 1.39±1.1 mmol/l (0.17–7.44 mmol/l). 84.4% of patients had low calcium content in daily urine. The mean blood concentration of ionized calcium was 1.26±0.05 mmol/l (1.16–1.53 mmol/l). Hypercalcemia was observed in 8.3% of patients. Osteoporosis in the proximal femur was registered in 32.9% of patients, in the lumbar spine – in 18.1% of patients. In patients with normal vitamin D level the mean urinary calcium excretion was 1.77±1.2 mmol/l, with vitamin D deficiency – 1.1±0.7 mmol/l (p=0.07). In patients with low calcium excretion in the urine, the mean blood concentration of vitamin D was 18.7±7.7, with normal excretion – 28.5±10.8 ng/ml (p=0.007). Significant inverse relationships were registered between urinary calcium excretion and creatinine (r=-0.36; p<0.0001). In the group of patients with low urinary calcium excretion the mean creatinine level reached 102.3±23.9 µmol/l, with normal excretion – 84.9±11.2 µmol/l (p<0.0001). There was a significant direct correlation between daily urinary calcium excretion and glomerular filtration rate, estimated using the CKD-EPI formula (r=0.39; p<0.0001) and an inverse correlation between blood calcium and GFR (r=-0.26; p=0.01). Significant direct relationship was registered between the blood concentration of ionized calcium and the creatinine (r=0.2; p=0.05) and urea (r=0.32; p=0.04) concentration. Conclusion. The study results demonstrate a low level of calcium excretion in the urine in old and very old patients with coronary artery disease. The urine calcium excretion is primarily due to impaired renal function and low vitamin D concentration.