Adrenomedullin as a marker of hypoxia, not hypoperfusion. Letter regarding the article ‘Biologically active adrenomedullin as a marker for residual congestion and early rehospitalization in patients hospitalized for acute heart failure: Data from STRONG‐HF’

Abstract

We read with great interest the article by Voordes et al., 1 which reports that a high level of biologically active adrenomedullin (bio-ADM) in blood is significantly associated with the severity of congestion, a condition that can cause hypoxia, but not with low left ventricular ejection fraction, indicative of hypoperfusion. However, the authors did not mention if a direct association is present between bio-ADM and hypoxia. Notably, hypoxia plays a key role in elevating ADM levels. The key molecular factor of interest is hypoxiainducible factor-1, which was shown to upregulate ADM expression under hypoxic conditions in in vitro 2 and in vivo 3 studies, leading to arteriogenesis and angiogenesis as compensatory responses. 4 Our clinical study indicates that elevated blood mid-regional proADM levels serve as a promising non-invasive marker of increased oxygen extraction fraction, which is equivalent to tissue hypoxia but not as a marker of decreased cerebral blood flow. This was assessed using 15 O-gas brain positron emission tomography in patients with carotid artery stenosis or occlusion. 5 Therefore, ADM shows potential as a marker for assessing hypoxic status in cardiovascular as well as cerebrovascular diseases.