Para aminohippurate<unk>  or<unk>  is a method used in renal physiology to measure renal plasma flow, which, in turn, is a measure of renal function.
The concentration of para aminohippurate <unk>  is measured in one arterial blood sample (PPAH) and one urine sample(UPAH). The urine flow (V) as also measured. Renal perfusion flow is then calculated by:
What in fact is calculated is the effective renal plasma flow (eRPF). However, since the renal extraction ratio of<unk>  almost equals 1, then eRPF almost equals RPF.
PAH clearance
Volumetric flow rate
Ventilation/perfusion ratio
Diffusion capacity
Arteriovenous oxygen difference
Alveolar gas equation
Stroke volume
Oxygen Enhancement Ratio