849
Seven of these 12 patients had elevated serum ferritin levels in 1994 ; 6 of the 7 had further increases in 1998 , and 1 had a decrease , although the value remained elevated .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 None