WHAT IS HYPERKALAEMIA?

Hyperkalaemia is a metabolic condition characterised by elevated serum potassium levels (>5.0 mEq/L)1

Even a small increase in extracellular potassium may have significant effects on cardiovascular and neuromuscular function.2,3 

Full colour vision of the body figure with all organs and vascular network highlighted
Full colour vision of the body figure with all organs and vascular network highlighted

Potassium is essential for:4,5 

  • Maintenance of total body volume
  • Acid and electrolyte balance
  • Normal cell function

Normokalaemia (extracellular K+ maintained within 3.5 – 5.0 mEq/L3) is regulated by several factors, including internal and external potassium homeostasis.6

Hyperkalaemia is typically asymptomatic, and can be unpredictable. There is no reliable indicator of the degree of hyperkalaemia a patient can tolerate without experiencing an adverse event.7

  1. Rastergar MS. Postgrad Med J. 2001;77: 759-764.
  2. Crawford AH. J Infus Nurs. 2014;37(3):167-175.
  3. Alfonzo AVM, et al. Resuscitation. 2006; 70(1):10-25.
  4. Palmer BF. Clin J Am Soc Nephrol. 2015;10:1050-60.
  5. Gumz M et al. N Engl J Med. 2015;373:60-72.
  6. Zacchia M et al. Kidney Dis. 2016;2:72-79.
  7. Welch A et al. Nephrol Dial Transplant. 2013;28 (1):15-16.

WHAT IS HYPERKALAEMIA?

  1. Rastergar MS. Postgrad Med J. 2001;77: 759-764.
  2. Zacchia M et al. Kidney Dis. 2016;2:72-79.

WHAT IS HYPERKALAEMIA?

Internal potassium homeostasis1

After a meal, changes in extracellular fluid (ECF) are initially buffered by movement of potassium into or out of skeletal muscle. Under normal conditions, this is regulated by insulin and catecholamines:1

Insulin increases Na+-K+-ATPase activity and plasma membrane expression via phosphatidylinositide- 3-kinase (PI3-K), atypical protein kinase C (aPKC), and ERK1/2 mitogen- activated protein kinase pathway.

Catecholamines increase Na+-K+-ATPase activity through binding to the β2-adrenergic receptor on the cell membrane, which triggers the cAMP and protein kinase A (PKA) dependent pathway.

Schematic of a skeletal cell to show the effect of insulin and catecholamine binding on cation exchange through the cell membrane
Schematic of a skeletal cell to show the effect of insulin and catecholamine binding on cation exchange through the cell membrane

Adapted from Palmer BF. Clin J Am Soc Nephrol. 2015;10:1050-60.1

  1. Palmer BF. Clin J Am Soc Nephrol. 2015;10:1050-60.

WHAT IS HYPERKALAEMIA?

External potassium homeostasis1

Once potassium is absorbed, it circulates to the kidneys where it is regulated through a complex process of active secretion and absorption in the distal tubule and collecting ducts.1

Potassium excretion in the kidneys is regulated by the renin-angiotensin- aldosterone system (RAAS), which becomes stimulated following a decrease in kidney perfusion.1,2

Diagram to show how the renin–angiotensin–aldosterone system acts upon the kidneys to regulate potassium levels in the body
Diagram to show how the renin–angiotensin–aldosterone system acts upon the kidneys to regulate potassium levels in the body

Adapted from Palmer BF. N Engl J Med. 2004; 351: 585-92.3

  1. Palmer BF. Clin J Am Soc Nephrol. 2015;10:1050-60.
  2. Edwards S. Nurs Stand. 2001;15:36-42.
  3. Palmer BF. N Engl J Med. 2004; 351: 585-92.

WHAT IS HYPERKALAEMIA?

Cardiovascular effects1

Hyperkalaemia alters the transmembrane potassium gradient, which can disrupt the membrane potential in cardiac muscle.

This is associated with abnormal ECG manifestations, including:1

  • Tented T waves
  • Prolonged PR interval
  • Widened QRS complex

In more severe cases, hyperkalaemia can cause arrhythmias, ventricular fibrillation or asystole.1

Potential progressive changes in ECG with increasing severity of hyperkalaemia
Potential progressive changes in ECG with increasing severity of hyperkalaemia

Adapted from UK Renal Association Clinical Practice Guidelines, 2014.2

  1. Kovesdy CP. AM J Med. 2015; 128: 1281-7.
  2. UK Renal Association Clinical Practice Guidelines. 2014. Treatment of Acute Hyperkalaemia in Adults.

WHAT IS HYPERKALAEMIA?

Neuromuscular effects1

Hyperkalaemia alters the transmembrane potassium gradient, which can disrupt the membrane potential in skeletal muscle. This can lead to a number of neuromuscular effects, including:1

 

Muscle fibre icon
Muscle fibre icon

Myalgia
Muscle weakness
Paralysis

Kidney icon
Kidney icon

Vomiting
Diarrhoea
Nausea

  1. Crawford AH. J Infus Nurs. 2014;37(3): 167-175.