# Undetectable brain natriuretic peptide as a marker of ultrasound-detected hypovolemia in patients with cancer on active treatment

## TL;DR

This study explores using undetectable BNP levels as a marker for hypovolemia in cancer patients, based on ultrasound measurements of the inferior vena cava.

## Contribution

The study is the first to link undetectable BNP levels with ultrasound-detected hypovolemia in cancer patients.

## Key findings

- Undetectable BNP levels may indicate hypovolemia when physical exams are unclear.
- The study found wide confidence intervals due to a small sample size.
- Temporal variability of BNP and IVC measurements may introduce bias.

## Abstract

Hypovolemia is a common complication in patients undergoing cancer-related therapies, yet assessing volume status in this population is challenging because of confounding comorbidities. This retrospective study is the first of its kind to examine the relationship between hypovolemia, assessed by measuring inferior vena cava (IVC) diameter via transthoracic echocardiogram (TTE) as an indicator of fluid status, and brain natriuretic peptide (BNP) levels, a cardiac neurohormone released by the ventricles in response to increased pressure. We hypothesized that undetectable BNP levels (<10 pg/mL) would associate with small IVC diameters indicative of hypovolemia. Although our study revealed wide confidence intervals reflective of a small sample size, our findings suggest that undetectable BNP, a readily available laboratory marker, may serve as an indicator of hypovolemia when physical examination findings are inconclusive. In addition, our study was limited by the 2-week temporal variability of BNP and IVC measurements, which may potentially introduce bias because of the dynamic fluctuation of volume status. Further studies with larger cohorts and closer temporal alignment of BNP and TTE measurements are needed to validate these findings.