The mature form of adrenomedullin correlates with brain natriuretic peptide in plasma of chronic hemodialysis patients

Natriuretic peptide and adrenomedullin levels in chronic renal failure and effects of peritoneal dialysis

Plasma levels of B-type natriuretic peptide (BNP) and its N-terminal propeptide (NT-BNP) are elevated in renal impairment and provide a robust prognostic index. The effect of peritoneal dialysis on plasma NT-BNP, however, is unknown. Furthermore, no information exists regarding levels of the N-terminal propeptide for C-type natriuretic peptide (NT-CNP) in renal failure and the effects of peritoneal dialysis. Accordingly, we documented venous levels of these peptides, and adrenomedullin, across peritoneal dialysis. We measured venous BNP, NT-BNP, NT-CNP, adrenomedullin, blood urea nitrogen (BUN) and creatinine before, during and after completion of overnight peritoneal dialysis in 11 patients, and identical sampling was carried out in eight patients (controls) but between peritoneal dialysis treatments. Peptide levels were measured using well-validated, published methods. Baseline levels of NT-CNP (212, 150-303 pmol/l, median and 25th and 75th percentiles) were much higher than recorded previously in healthy volunteers or in heart failure, and correlated with plasma creatinine (rs=0.53, P<0.05). Peritoneal dialysis had no effect on plasma NT-CNP, nor on NT-BNP, BNP or adrenomedullin (all elevated above normal), whereas both BUN and creatinine levels, as expected, declined (P<0.001). We conclude that plasma levels of NT-CNP are grossly elevated in chronic renal failure and correlated with plasma creatinine, but are not altered by peritoneal dialysis. Likewise, BNP, NT-BNP and adrenomedullin are elevated but are not altered by peritoneal dialysis. This information is needed if levels of these hormones are to be used as prognostic indicators or as a guide to the management of patients with chronic renal failure.

Natriuretic Peptides and the Dialysis Patient

The natriuretic peptide family consists of four structurally similar, but genetically distinct molecules with pronounced cardiovascular and renal actions. They are counterregulatory hormones playing an important role in fluid volume homeostasis. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) cause diuresis, natriuresis, and vasodilatation. C-type natriuretic peptide (CNP) has antimitogenic effects and causes vascular smooth muscle relaxation. Dendroaspis natriuretic peptide (DNP) shares many of the actions of ANP and BNP, but its function in humans is not yet fully understood. Natriuretic peptides have been extensively investigated as biochemical markers of the fluid state. Levels are elevated in disease conditions characterized by fluid overload and are closely related to survival in various cardiac disease states. In the dialysis population, BNP correlates significantly with cardiac function, whereas ANP is sensitive to volume changes during dialysis. However, changes in concentration do not predict achievement of euvolemia, and short half-life, combined with complicated assay techniques, make ANP a less than satisfactory tool for assessing hydration. BNP is a superior prognosticator for risk stratification in dialysis patients, and serial estimations will help in the identification of occult cardiac disease.

Adrenomedullin reflects cardiac dysfunction, excessive blood volume, and inflammation in hemodialysis patients

BACKGROUND

Plasma adrenomedullin (AM) reflects cardiac dysfunction and predicts survival after myocardial infarction. The present study was designed to investigate whether the mature AM (mAM) reflects status of cardiac function, systemic blood volume, or inflammation in hemodialysis patients with cardiovascular disease, and whether mortality and additional cardiovascular morbidity can be predicted by mAM.

METHODS

Plasma levels of mAM, atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), norepinephrine (NE), and C-reactive protein (CRP) before hemodialysis were measured in 67 chronic hemodialysis patients with cardiovascular disease, along with 2-dimensional and Doppler echocardiographic variables.

RESULTS

By univariate regression analysis, mAM correlated negatively with pulmonary venous flow velocity ratio and left ventricular (LV) ejection fraction and positively with LV inflow velocity ratio, LV end-diastolic, end-systolic volume indexes, plasma CRP level, and removal fluid volume by ultrafiltration. Multivariate stepwise regression analysis revealed that mAM reflected all variables better than log [ANP], log [BNP], and log [NE]. During a 1-year follow-up period, 7 patients died and 8 had additional cardiovascular events. Event-free Kaplan-Meier curves based on the median mAM (4.55 pmol/L) showed that patients with high plasma mAM levels had higher mortality and morbidity than those with low plasma mAM levels (P = 0.0056). By Cox multivariate proportional hazard analysis, mAM was related to mortality and morbidity [hazard ratio (HR) 4.55, 95% CI 1.2-16.8, P= 0.023).

CONCLUSION

Plasma mAM reflects cardiac dysfunction, excessive blood volume, and inflammation better than ANP, BNP, and NE, resulting in a predictor of mortality and cardiovascular morbidity in hemodialysis patients with cardiovascular disease.

Natriuretic Peptides in ESRD

Natriuretic peptides are involved in the regulation of volume homeostasis. Their levels generally are increased in the setting of volume expansion and act on multiple effector systems to cause vasodilation and natriuresis in an effort to return volume status back to normal. In patients with end-stage renal disease, the natriuretic capabilities of these peptides are limited. However, there has been much interest in the potential applicability of measurement of these peptides as a surrogate marker of volume status and in the determination of dry weight. Furthermore, atrial natriuretic peptide and brain natriuretic peptide can serve as markers of left ventricular dysfunction and may have utility in determining cardiac prognosis in patients on long-term dialysis therapy.

Relationship of plasma Dendroaspis natriuretic peptide-like immunoreactivity and echocardiographic parameters in chronic haemodialysis patients

BACKGROUND AND AIMS

The Dendroaspis natriuretic peptide (DNP), which was recently isolated from the venom of the green Mamba snake, Dendroaspis angusticeps, is a 38 amino acid peptide containing a 17 amino acid disulfide ring structure. The purpose of this study was to evaluate the effect of haemodialysis (HD) on the plasma concentration of DNP, and to investigate the relationship between the 2-D echocardiographic parameters and the changes in the plasma DNP levels during HD.

METHODS

Forty-five haemodialysis patients and 22 healthy individuals underwent a measurement of plasma DNP-like immunoreactivity, serum creatinine, haematocrit, blood pressure and bodyweight before and after each HD session. Echocardiography was performed before and after HD. The peak early diastolic transmitral flow velocity (E), peak late diastolic transmitral flow velocity (A), and E/A ratio were measured by using a pulsed Doppler echocardiogram.

RESULTS

The plasma DNP-like immunoreactivity of those in the pre-HD state was significantly higher (235.6 +/- 45.8 pg/mL) than those of the healthy subjects (105.3 +/- 31.1 pg/mL). In addition, the plasma DNP-like immunoreactivity was significantly decreased after HD (204.4 +/- 55.4 pg/mL). The left atrial diameter, left ventricular diameter at end diastole and end systol, E velocity, A velocity, E/A ratio and inferior vena cava diameter were significantly decreased after HD. There were significant correlations between the changes of plasma DNP-like immunoreactivity and the changes in the bodyweight and inferior vena cava diameter, respectively.

CONCLUSION

These results suggest that the plasma DNP-like immunoreactivity might be involved in the regulation of the blood volume in patients undergoing HD.