Hyperkalaemia DDx

Overview

• Hyperkalaemia is defined as serum potassium level > 5.5 mEq/L
• Hyperkalaemia is potentially life-threatening due to the risk of cardiac dysrhythmias
• Most patients begin to manifest significant ECG changes at serum levels > 6.5 mEq/L

Causes

Increased potassium intake (rare)

• Oral (potassium supplements)
• IV (transfusion of stored blood, supplement infusions)
• Gastrointestinal hemorrhage

Increased release from tissues

• Tissue injury
• Rhabdomyolysis, tumour lysis syndrome
• Burns, ischaemia, haemolysis
• Intense physical activity
• hyperthermia

Decreased renal excretion

• Renal failure (acute and chronic)
• Hypoaldosteronism, Addison’s, Chronic active hepatitis
• Obstructive uropathy

Transcellular shift

• Acidosis:
  • Metabolic acidosis (diabetic ketoacidosis, mineral acid overdose)
  • Respiratory acidosis

Factitious (Pseudo-hyperkalaemia)

• Laboratory error
• Haemolysis of sample, clenched fist, ischaemic tourniquet
• Sample taken from IV running potassium-containing fluid
• Leucocytosis, thrombocytosis

Drugs causing hyperkalaemia

• Transcellular shift/ release from tissues
  • Suxamethonium, Beta blockers, phenylephrine
• Aldosterone inhibition
  • ACE inhibitors, Angiotensin II blockers
  • Heparin, spironolactone, Beta blockers
• Increased aldosterone resistance (Trimethoprim, amiloride)
  • Inhibition Na/K/ATPase (Digoxin)
• Potassium supplements and IV additives (Increase exogenous potassium)

References and Links

LITFL

• CCC – Hyperkalaemia management
• CCC – Hyperkalaemia
• CCC – Hypokalaemia
• CCC – Hypokalaemia Mind Map
• ECG Library – Hyperkalaemia
• ECG Library – Hypokalaemia
• Clinical Case – Hyperkalaemia

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia,  HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia,  ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

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