Overview
Why Arteriolar Tone Changes GFR
An eGFR change after a new drug is a pressure signal before it is a diagnosis.
CNPLE
CNPLE
An eGFR change after a new drug is a pressure signal before it is a diagnosis. The relevant question is whether glomerular capillary pressure has shifted in an expected, controlled way or whether renal perfusion is failing. Afferent tone governs blood entering the glomerulus; efferent tone governs resistance to blood leaving it. Their relative tone sets filtration pressure. This model explains two apparently similar but clinically different findings. ACE inhibitors and ARBs, as well as SGLT2 inhibitors, can cause an early eGFR dip through haemodynamic adjustment. In contrast, hypovolaemia, an NSAID, and RAS blockade can produce abrupt AKI by removing compensatory responses on both sides of the glomerulus. A patient with vomiting who takes an ARB, diuretic, and ibuprofen therefore needs a perfusion and medication assessment before the result is labelled drug nephrotoxicity.
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