Beta 2-microglobulin. A reliable parameter for differentiating between graft rejection and severe infection after cardiac transplantation

Factors other than the glomerular filtration rate that determine the serum beta-2-microglobulin level

Background

β2-microglobulin has been increasingly investigated as a diagnostic marker of kidney function and a prognostic marker of adverse outcomes. To date, non-renal determinants of β2-microglobulin levels have not been well described. Non-renal determinants are important for the interpretation and appraisal of the diagnostic and prognostic value of any endogenous kidney function marker.

Methods

This cross-sectional analysis was performed within the framework of the www.seniorlabor.ch study, which includes subjectively healthy individuals aged ≥60 years. Factors known or suspected to have a non-renal association with kidney function markers were investigated for a non-renal association with serum β2-microglobulin. As a marker of kidney function, the Berlin Initiative Study equation 2 for the estimation of the estimated glomerular filtration rate (eGFR_BIS2) in the elderly was employed.

Results

A total of 1302 participants (714 females and 588 males) were enrolled in the study. The use of a multivariate regression model adjusting for age, gender and kidney function (eGFR_BIS2) revealed age, male gender, and C-reactive protein level to be positively associated with β2-microglobulin levels. In addition, there was an inverse non-renal relationship between systolic blood pressure, total cholesterol and current smoking status. No association with markers of diabetes mellitus, body stature, nutritional risk, thyroid function or calcium and phosphate levels was observed.

Conclusions

Serum β2-microglobulin levels in elderly subjects are related to several non-renal factors. These non-renal factors are not congruent to those known from other markers (i.e. cystatin C and creatinine) and remind of classical cardiovascular risk factors.

Cardiac transplantation for the cardiologist not trained in transplantation

This review focuses on selected aspects of the treatment of patients being evaluated for and undergoing cardiac transplantation. Cardiac transplantation is a potential therapeutic option for a variety of irreversible cardiac disorders when the symptomatic status and anticipated survival after transplantation exceeds that of the patient's condition. The timing of cardiac transplantation with respect to prognosis is aided by the measurement of baseline hemodynamics and maximal aerobic capacity. Major cardiac problems that occur after transplantation include an increased early risk of acute allograft rejection and, later, the occurrence of allograft coronary artery disease. Furthermore, cardiac transplant recipients have unique "normal" physiologic alterations with respect to intracardiac hemodynamics, exercise capacity, the effects of denervation, and expected electrocardiographic and echocardiographic findings.