2771
It is suggested that the use of endogenous creatinine clearance to estimate the glomerular filtration rate ( GFR ) requires caution and the recognition of the limitations of the method , and that simpler techniques ( serum creatinine or estimated endogenous creatinine clearance ) are preferable in routine practice .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None