DR.RAVI DEPT OF PEDIATRICS MGMCRI

1. POTTASIUM METABOLISM
& APPROACH TO
HYPERKALEMIA
BY DR.RAVI KUMAR S
1ST YEAR PEDIATRIC PG
MGMCRI

2. TABLE OF CONTENTS
INTRODUCTION
PHYSIOLOGY OF K⁺
EXCRETION OF K⁺
DEFINITION OF HYPERKALEMIA
CLINICAL FEATURES
ETIOLOGY
TREATMENT

3. Introduction
Potassium an essential cation for cellular functions, is widely distributed in body.
One of the most commonly affected ions in sick children.
Normal Sr.K⁺ ranges between 3.5 to 5 mEq/L
Common K⁺ rich foods are Meats, Beans, Fruits & Potatoes.

4. Physiology
Nearly 98% of potassium is distributed in the ICS with a conc. Of 140-150 mEq/L.
About 3/4th of Intracellular K⁺ is in muscles, 2% K⁺ is in ECS, mostly in bones.
The intercellular to extracellular potassium gradient is maintained by sodium potassium
triphosphatase and selective K⁺ channel.
Na-K-ATPase allows active transport of Potassium into cells whereas selective channels allow
passive diffusion of K⁺ out of cells.
Potassium homeostasis depends on a number of renal and extra renal factors like intake,GI and
Urinary losses and transcellular shift.
Daily requirement of K is about 1-2 mEq/kg.

6. Excretion of K⁺
Kidney is the primary organ for excretion of K⁺ upto 90%
Nearly 85-90% of K⁺ is reabsorbed up to distal tubules and only 10-15% reaches cortical and
outer medullary collecting ducts, which is the principle site of regulation of potassium excretion.
Potassium secretion in cortical collecting duct (CCD) is regulated by aldosterone secreted from
adrenal cortex.
The net K⁺ secretion of CCD level evaluated by Transtubular K⁺ conc gradient (TTKG)
TTKG = Urine K⁺ x Sr osmolality / Sr potassium x Urine Osmolality)
In Hypokalemic children TTKG >4 indicates renal loss of K⁺
In Hyperkalemic children TTKG <8 indicates impaired renal secretion of K⁺

8. Hyperkalemia
DEFINITION
Sr.K⁺ >5.5 mEq/L
Based on the Sr. K⁺ concentration, Hyperkalemia can be categorized as
Mild (5.5 to 6.5 mEq/L)
Moderate (6.6 to 8 mEq/L)
Severe (>8 mEq/L)

9. Etiology
Spurious raised levels :
Release of K⁺ from Hemolysed RBC at the time of blood sampling.
True Hyperkalemia :
Increased load
Impaired renal excretion
Transcellular shift of K⁺

10. Etiology
Increased Load
A) Exogenous Source : Salt Supplements, Transfusion.
B) Endogenous Source : Intravascular hemolysis, resolving hematoma, rhabdomyolysis & tumor lysis.
Impaired Renal Excretion
A) ↓ed Na & H20 delivery to distal cortical tubules : AKD or Volume Depletion
B) Functional Aldosterone :
Hypoaldosteronism with ed Renin levels – Primary Adrenal Disease(Addison, CAH), Aldosterone
synthase deficiency, use of drugs (ACE inhibitors, Angiotensin receptor blocker)
Renal Tubular Diseases : Bartter syndrome –type II, Urinary Tract obstruction, Kidney transplant
Potassium sparing diuretics & NSAIDS

11. Etiology
Transcellular shift
Acidosis
Hypertonicity
Exercise
Diabetes
Myolysis
Drugs like Digoxin, Beta blockers & Succinylcholine
Extensive Muscle/ Cellular Injury
Malignant hyperthermia

12. Clinical Features

13. TREATMENT
If plasma K⁺ >6.5 mEq/L or ECG abnormalities are detected, emergency treatment should be
initiated.
Priority of Rx
1. Withdrawl of Source if any; in case blood transfusion is urgently needed use of fresh &
washed RBC’s are recommended,
2. Stabilization of myocardial cells.
3. Rapid reduction of plasma K levels with transcellular shift.
4. Enhance K elimination from body
5. Treatement of underlying cause.

14. TREATMENT
 10 % calcium gluconate 0.5-1 ml/kg (max 10 ml) 1:1 diluted with saline over 10 min under
cardiac monitoring.
 Glucose insulin infusion :
Infants & Young children : 2ml/kg of 25% D with 0.1 Units/kg of regular insulin over 30 mins.
Older children : 50 ml in 50% D with 10 Units of regular insulin to be infused over 30 min.Should
be monitored for hypoglycemia.
Short acting beta agonist : Salbutamol Neb 2.5 -5 ml in 3ml NS over 20 mins
If there is Non anion gap acidosis, 1-2mEq/kg of Sodium bicarbonate iv over 30 mins.
Ion exchange Resin : sodium polysterene sulfonate (Kayexalate) 1-2g/kg PO or PR
IV Furosemide 1-2 mg/kg if Kidney function is normal
Hemodialysis/ Peritoneal Dialysis with K free fluid.