Am.  Jour.  Pharm. 
October,  1920. 
Urinary  Casts. 
719 
instances  fat),  and  may  be  fine  or  coarse,  giving  rise  to  finely  granu- 
lar and  coarsely  granular  casts.  The  granulated  hyaline  casts  are 
longer,  narrower  and  lighter.  The  granules  are  not  as  coarse  and 
irregular  transparent  areas  are  apparent.  These  granules  are  com- 
posed of  amorphous  urinary  salts  (usually  urates),  which  dissolve 
upon  the  addition  of  a  drop  of  acetic  acid. 
Epithelial  Casts. — Epithelial  casts  consist  mainly  of  the  epi- 
thelial cells  lining  the  uriniferous  tubules,  and  these  casts  are  at 
times  found  covered  with  mineral  and  organic  deposits.  The  indi- 
vidual cells  are  of  varied  shape  and  size,  with  a  usually  distinct 
nucleus.  Epithelial  casts  are  observed  frequently  in  acute  patho- 
logical conditions  of  the  kidney. 
Fatty  Casts. — Under  this  heading  are  included  casts  in  which 
the  greater  part  of  their  surface  area  is  covered  with  fat  globules 
or  crystals  of  fatty  acids.  They  are  met  with  usually  in  fatty  de- 
generation of  the  kidneys. 
Blood  Casts. — Casts  densely  covered  with  erythrocytes  consti- 
tute what  is  known  as  blood  casts.  The  individual  red  blood  cells 
may  be  of  normal  appearance,  but  more  frequently  they  are  de- 
colorized and  swollen.  Occasionally  other  abnormal  shapes  are 
observed,  representing  various  stages  of  degeneration.  They  are 
usually  indicative  of  the  occurrence  of  hemorrhage,  which  is  not 
uncommon  in  acute  renal  disorders. 
Pigment  Casts. — -In  the  later  stage  of  renal  hemorrhage,  the 
blood  cells  in  the  cast  are  usually  disintegrated.  The  breaking  down 
of  the  erythrocytes  leaves  only  flakes  of  pigment,  which  become 
imbedded  within  the  cast,  and  form  what  is  known  as  pigment 
casts. 
Leukocyte,  Pus  or  Purulent  Casts. — In  a  chronic  suppurative 
renal  condition,  which  is  not  so  frequently  observed,  these  casts 
are  met  with.  They  are  usually  hyaline  casts,  thickly  coated  with 
masses  of  leukocytes,  which  may  be  of  normal  shape  and  size,  or 
in  a  degenerative  state.  At  times,  they  are  mistaken  for  epithelial 
casts.  Upon  the  addition  of  acetic  acid,  the  neuclei  become  visible 
and  the  differentiation  between  these  two  types  becomes  easy. 
Fibrinous  Casts. — In  cases  of  renal  hemorrhage,  there  may  be 
found  casts  composed  almost  entirely  of  coagulated  fibrin.  Upon 
the  addition  of  acetic  acid,  they  become  almost  invisible. 
Bacterial  Casts. — These  are  rare.  They  may  be  occasionally 
found  in  cases  of  suppurative  nephritis.    They  differ  from  the  true 
