Cystatin C kidney function tests

MrPain

Can this test be done by a regular GP or is it usually done by a renel specialist?
The reason I ask this is I wonder how would one get an accurate indication renal function in athletes where creatinine clearence results may not be accurate due to increased muscle mass.

SomeDose

I doubt even a specialist renal unit would measure cystatin C, certainly not routinely anyway. Standard formulae such as the Cockcroft & Gault (CrCl) and MDRD (eGFR) do adjust for age, weight and sex so to a certain extent they will account for the higher than "normal" levels of creatinine seen in young fit males or african-americans for example. Plug a serum creatinine of 150micromol/L into the equations to compare an 85kg (non-obese) 25yo male and a 50kg 75yo female and you'll see the vastly different levels of renal function.

I imagine the more advanced tests such as those using cystatin C, radioisotopes etc are of little or no value in practice, where standard measurements combined with clinical indicators, variation from baseline renal function, urine output etc provide sufficient information. They're probably more relevant in a trial setting or physiological studies where accurate GFR measurments are more important.

Tree

Aye Cystatin C shows promise as an indicator of renal function, but the gain is insufficient for it to supercede creatinine in routine use. Maybe if you were enrolled on a kideny fucntion research panel they might use cystatin C....