""^^b^aryfmr"}       Preparation  of  Thyroid  Extract.  65 
Iodine  in  Milligrammes  Per  Gramme  of  Fresh  Gland  from  Different 
Species. 
Pig. 
Sheep. 
Beef. 
Human. 
.084 
.006 
.030 
.060 
.120 
.013 
.040 
.080 
.300 
.016 
.103 
.094 
.300 
.016 
.165 
.200 
.648 
.018 
.168 
.216 
.710 
.018 
.187 
.316 
1.040 
.020 
.260 
•415 
1.340 
.041 
•445 
.615 
1.470 
.214 
.610 
.814 
2.050 
.318 
.700 
2.88 
415 
1.020 
1.470 
From  the  above  table  it  is  evident  that  the  iodine-content  of  thy- 
roid glands  shows  wide  variations.  Before  being  used  therapeutically 
it  is  essential  that  the  proteid  should  be  standardized  on  the  basis  of 
its  iodine  content,  and  a  uniform  intelligent  dosage  regulated  thereby. 
For  the  standard  we  have  selected  the  proteid  obtained  from  normal 
human  thyroid  glands. 
The  average  figures  of  a  large  number  of  iodine  analyses  of  the 
proteid  obtained  from  normal  human  thyroid  glands  by  the  process 
above  described,  namely,  that  of  heating  the  acidified  extract  to  44° 
and  thoroughly  washing  the  precipitate,  is  as  follows : 
ONE  GRAMME  OF  THE  PURIFIED  PROTEID  FROM  NORMAL  HUMAN  THY- 
ROID GLANDS  CONTAINS  3.384  MILLIGRAMMES  OF  IODINE. 
After  the  purified  proteid  from  the  animal  glands  is  obtained, 
its  iodine  content  is  determined  after  the  method  devised  by  Dr. 
Riggs,  noted  above,  and  regardless  of  whether  this  proteid  is  richer 
or  poorer  in  iodine  than  the  standard,  it  is  considered  that  each 
3.384  mgms.  of  iodine  represent  one  gramme  of  the  active  thyroid 
proteid.  For  the  purpose  of  therapeutic  administration  the  proteid 
is  diluted  with  the  appropriate  amount  of  lactose  and  made  up  into 
two-grain  tablets  by  the  usual  method.  Tablets  of  different  strengths 
are  prepared ;  i  per  cent.,  2  per  cent.,  and  5  per  cent,  tablets  have 
been  found  to  give  a  sufficiently  wide  variation  in  strength  to  answer 
