3890
Female subjects , including both normal subjects and idiopathic calcium stone - formers , have higher urinary cyclic AMP levels than their male counterparts , and this difference is significant when urinary cyclic AMP is expressed in the units mumol / g of creatinine .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None