Plasma levels of N-terminal proatrial natriuretic peptide in children are dependent on renal function and age

Potential and Limitations of Atrial Natriuretic Peptide as Biomarker in Pediatric Heart Failure-A Comparative Review

Although B-type Natriuretic Peptide (BNP), N-terminal-proBNP (NT-proBNP), and mid-regional-proANP (MR-proANP) are included in current guidelines on heart failure in adults, no guideline considering these biomarkers in pediatric heart failure is available. A new drug class of neprilysin inhibitors as fixed-dose combination (Sacubitril/valsartan) has been introduced and is currently being investigated in children suffering from heart failure. Atrial Natriuretic Peptide (ANP) is discussed as a more useful alternative to BNP because it may grants better insights into the effects of this treatment. Thus, this review aimed to provide an overview of the current knowledge concerning ANP in pediatric heart failure and compares its suitability regarding diagnosis and prognosis of heart failure. A literature search using PubMed resulted in 147 publications of which 22 studies were classified as relevant. The review presents available ANP, NT-proANP, and MR-proANP level data in children (0-18 years). Summarizing, ANP shows only minor differences as marker for diagnosing and monitoring pediatric heart failure if compared to BNP. Due to its fast release, ANP offers the advantage of displaying rapid changes during therapy or operation. ANP is -like the other natriuretic peptides- influenced by age, presenting with the highest levels in very young infants. ANP also correlates with atrial pressure and volume overload in children. In addition, ANP determination in saliva appears to be a promising alternative to blood sampling. Similarly to NT-proBNP, NT-proANP, and MR-proANP offer better stability but only few data has been published in children and thus their potential is only presumable so far.

Plasma atrial natriuretic peptide in healthy calves and calves with congenital heart disease

BACKGROUND

The basic and clinical implications of evaluating plasma atrial natriuretic peptide (ANP) concentration in calves are unknown.

OBJECTIVE

To investigate the relationship between the plasma ANP concentration and left ventricular end-diastolic pressure (LVEDP) in healthy calves subjected to volume overload (Study 1), and to compare the plasma ANP concentration in calves with or without heart disease (Study 2).

ANIMALS

Six healthy calves were used in Study 1; disease calves and sick calves with (n = 9) and without congenital heart disease (CHD) (n = 9) were used in Study 2.

METHODS

In Study 1, LVEDP in anesthetized calves was manipulated by IV administration of acetated Ringer's solution (rate of 100 mL/kg/h for 20 minutes) and furosemide. In Study 2, disease calves were identified by blood examination and echocardiography or pathological examination. The plasma ANP concentration was determined by a chemiluminescence enzyme immunoassay for human alpha-ANP.

RESULTS

In Study 1, preloading significantly increased the plasma ANP concentration (36 +/- 20-185 +/- 156, P < .01) and LVEDP (-11 +/- 7-2 +/- 12, P < .01) from the baseline. Furthermore, plasma ANP concentrations were strongly correlated with LVEDP (r= 0.61). In Study 2, the plasma ANP concentration was significantly higher in the calves with CHD than in the calves without heart disease (220 [67-970] versus 31 [10-86]; mean [range], P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Measurement of plasma ANP concentrations in calves can provide additional information useful for predicting hemodynamic abnormalities.

Atrial natriuretic Peptide in young and elderly children with mild gastroenteritis

Objective. Atrial Natriuretic Peptide (ANP) has natriuretic and diuretic effects, synthesized and stored in the atrial cells, released in response to stretch of the atrial muscle during increase venous return. Acute gastroenteritis (AGE) causes dehydration. We intend to determine whether the decrease in venous return due to dehydration would lead to a decrease in ANP levels. Patients and Methods. This is a prospective observational controlled study. Blood collected from 30 children with AGE and ANP's levels were compared with 25 controls. ANP levels were determined by radioimmunoassay. Results. The study group was in mild dehydration. As a significant difference was found in ANP levels between children in the 3mo–3y group and older children 3y–14y. We analyzed the results according to age. No difference was found between children with AGE and control, in the 3mo–3y, ANP was 12.1 ± 11 pg/ml versus 13.4 ± 12 pg/ml respectively, and 3 ± 2 versus 3.8 ± 3 pg/ml in the 3y–14y groups, respectively. Conclusion. Dehydration due to AGE does not change the ANP's plasma levels. A weak positive correlation between sodium levels and ANP was found r = 0.29. The significant finding of our study is the difference in ANP levels related to age, in the control as well as the GE group.

Radioimmunoassay for N-terminal probrain natriuretic peptide in human plasma

Measurement of plasma levels of natriuretic peptides has been used to assess left ventricular dysfunction and prognosis. Recently levels of the N-terminal peptide fragment of the precursor of brain natriuretic peptide have been reported to be present in peripheral plasma and to be increased in chronic heart failure patients. Our aim in this study was to develop a radioimmunoassay for N-terminal proBNP, to compare its plasma concentrations in control subjects and in patients with end-stage heart failure and to define its relation to brain natriuretic peptide (BNP). A polyclonal antibody was raised in rabbits against human N-terminal proBNP fragment (amino acid 1-21). The plasma N-terminal proBNP concentrations were assayed directly without extraction. No detectable cross-reactivity existed with other natriuretic peptides: BNP, ANP or N-terminal proANP. The assay had a detection limit (2 SD from zero) of 9.7 pmol/L. Plasma N-terminal proBNP was 29 (13-75) (median (range)) pmol/L in the control group. There were no gender difference, male: 28 (13-61) vs. female 33 (13-75) pmol/L, p= NS, but there was a positive correlation to age (r=0.52, p<0.0001). In patients with end-stage heart failure the median N-terminal proBNP levels were increased significantly 616 (114-2781) pmol/L (p<0.001) and in pooled data N-terminal proBNP showed a close correlation to BNP (r=0.96, p<0.0001). Size exclusion of plasma extracts indicated that proBNP (1-108) may circulate both as intact prohormone and as split products, N-terminal proBNP (1-76) and BNP (77-108). Our results support the concept that N-terminal proBNP measurement could be a valuable tool in the biochemical indication of increased cardiac wall stress.