RT Book, Section
A1 Emmett, Michael
A1 Wiederkehr, Michael R.
A2 Lerma, Edgar V.
A2 Rosner, Mitchell H.
A2 Perazella, Mark A.
SR Print(0)
ID 1149111632
T1 Disorders of Potassium Balance: Hypo- and Hyperkalemia
T2 CURRENT Diagnosis & Treatment: Nephrology & Hypertension, 2e
YR 2017
FD 2017
PB McGraw-Hill Education
PP New York, NY
SN 9781259861055
LK accessmedicine.mhmedical.com/content.aspx?aid=1149111632
RD 2023/09/23
AB Potassium  is  the  principal  cation  of  the  intracellular  fluid  (ICF)  where  its  concentration  is  between  120  and  150  mEq/L.  The  extracellular  fluid  (ECF)  and  plasma  potassium  concentration  [K]  is  much  lower—in  the  3.5-  to  5-mEq/L  range.  This  very  large  transcellular  gradient  is  maintained  by  active  K  transport  via  the  Na/K  ATPase  pumps  present  in  all  cell  membranes  and  the  ionic  permeability  characteristics  of  these  membranes.  The  resulting  30–40  fold  transmembrane  [K]  gradient  is  the  principal  determinant  of  the  transcellular  resting  potential  gradient,  which  is  about  90  mV,  with  the  cell  interior  negative  (Figure  4–1).  Normal  cell  function  requires  maintenance  of  the  ECF  [K]  within  a  relatively  narrow  range.  This  is  particularly  important  for  excitable  cells  such  as  myocytes,  conducting  tissues,  and  neurons.  The  pathophysiologic  effects  of  hypokalemia  and  hyperkalemia  on  these  cells  result  in  most  of  the  clinical  manifestations.