Kidney function is important to assess in the management of heart failure. Yet many studies and clinical practice focus on the glomerular filtration rate, while much less is known about the prevalence, predictors, and clinical outcome of tubular function in patients with heart failure.
Proximal tubular function is of great relevance to patients with heart failure, since the proximal tubule plays a vital role in renal sodium handling, sodium retention, and diuretic response. The tubular maximum phosphate reabsorption capacity (TmP/GFR) can be considered a parameter of proximal tubular function and, as such, was investigated for the first time in patients with heart failure.
In the visual abstract displayed above, the main findings of the study are outlined.
In this study, Emmens et al calculated TmP/GFR in 2085 patients with heart failure from a multinational, European cohort (BIOSTAT-CHF cohort) and 78 patients with acute heart failure from EMPA-RESPONSE-AHF. They found that TmP/GFR, as a measure of proximal tubular function, is frequently reduced in heart failure, especially in those patients with more advanced heart failure. In addition, lower TmP/GFR was associated with future risk of plasma neutrophil gelatinase-associated lipocalin (better known as NGAL, a tubular damage marker) doubling over time and worse clinical outcomes. These associations were independent of glomerular function.
Finally, administration of empagliflozin did not affect TmP/GFR after adjusting for eGFR.
“Looking beyond glomerular function with a relevant metric of proximal tubular function will provide valuable cardiorenal insights”