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Hyperkalaemia- Raised Potassium

Hyperkalaemia is defined as serum potassium level higher than 5.5 mmol/L.

Causes of raised potassium plasma levels- Haemolysed blood and prolonged or tight application of torniquet shift of potassium from blood cells to blood plasma by mechanical trauma Lab errors Thrombocytosis Leukocytosis ( ^^ WBC ) Lab errors Infectious mononucleosis Leukaemia Familial psedohyperkalaemia Dietary Supplements Total parenteral nutritional formulas Pencillin G Potassium therapy PRBC tranfusion Once GFR falls < 15-20 sig hyperkalaemia can occur even in abscence of an abnormally large K+ load Potassium sparing diuretics NSAIDs ACE inhibitors Angiotensin receptor blockers Cyclosporine or Tacrolimus Trimethoprim -sulfamethoxazole Heparin Ketoconazole Herbs Diabetes mellitus Sickle cell disease or Trait Lower urinary tract obstruction Adrenal insufficiency Primary Addison’s syndrome ( Autoimmune dis , TB or infarct ) Enzyme deficiencies Genetic disorders Metabolic acidosis Beta adrenergic blockade Acute tubular necrosis Electrical burns Thermal burns Cell depolarization Head trauma Digitalis toxicity Digitalis toxicity Methotrexate Rhabdomyolysis Tumour lysis syndrome Cyclosporine

Approach-Often incidental laboratory finding Rarely associated with symptoms Compains may be vague Ocassionally patients may c/o palpitations , nausea , muscle pain or paraesthesia , generalised fatigue Clinical affects are due to pathological effects of ↑ K+ conc on generation of action potentials in excitable tissues 
( Heart and Neuromuscular tissue )

AssessmentCardiac function ( eg ECG ) Renal function Kidneys and Urinary tract Hydration status ( fluid over load ) Blood pressure ( vol depletion ) Neurological evaluation Medications

Tests to considerGlucose Bicarbonate Blood Urea Nitrogen Serum creatinine Serum calcium Full Blood Count ECG All patients K+ value >= 6.0 should have a 12 lead ECG done urgently Cortisol and Alosterone ( r/o Addisons ) Urinalysis ( Rhabdomyolysis ) Creatinine phosphokinase ( CPK ) and Calcium 
( r/o Rhabdomyolysis ) ABG ( r/o acidosis ) Digoxin levels ( if on treatment ) Transtubular potassium gradient ( assessment of renal potassium handling ) Plasma renin activity Urine and plasma osmolality

Threshold for emergency treatment varies but most guidelines recommend that emergency treatment should be given if the serum K+ is >= 6.5 mmol/L with or without ECG changes
 If hyperkalaemia suspected on clinical grounds or ECG changes

ECG ChangesCauses a rapid reduction in resting membrane potential leading to ↑ ed cardiac depolarization and muscle excitability → this causes ECG changes ECG changes do not consistently follow a stepwise , dose-dependent pattern Risk of arrythmias ↑es with K+ values > 6.5 mmol and even a small elevation in K + above this conc can lead to rapid progression from peaked T waves to VF and asystole ECG changes may be normal even in presence of sig hyperkalaemia ECG changes may also be modified by the presence of co-existing metabolic disorders such as metabolic acidosis , Ca conc , Na conc and the rate of ↑ in K+ level It can affect the function of both temporary and permanent pacemakers

Pseudohyperkalaemia is also known by other names as
○ spurious
○ factitious
○ artefactual
 One of the most common testing errors in clinical laboratory
 It is defined as reported rise in serum K+ conc with normal effective plasma potassium concentration
 The most common cause is poor technique or practice during collection and preanalytic processing of blood sample
 Patient factors predisposing to psuedohyperkalaemia include
○ inherited defects in erythrocyte membrane structure
○ marked ↑ in platelet counts
○ marked ↑ in WCC 
 Consider if ↑↑ platelets in blood or leucocytes coincide with unexplained serum hyperkalaemia , typically in a patient who is known to suffer with renal problems or acidosis or who is does not take medications like ACEi’s and cardiac glycosides

Severity and UrgencyRefer urgently to secondary care ( same day ) if
○ K+ > 6.5 mmol / L
○ ECG changes and K + > 5.5 mmol/L
○ Potassium levels have risen > 0.5 mmol/L in the last 6-12 hrs
 All patients with K + > = 6 should have an ECG urgently
 Patients with chronic hyperkalaemia may be asymptomatic ( for e.g those with CKD ) at increased levels , while patients with dramatic acute potassium shifts may develop severe symptoms at lower ones

Due to ↑ risk of fatal arrythmias , hyperkalaemia needs urgent treament if its causing ECG abnormalities or the plasma K+ level is more than 6.5 mmol/L

Tall tented T waves Can also widen the T wave so that entire ST segment is incorporated into the upstroke of the T waves

May also cause Flattenning and even loss of the P wave ↑ of PR interval Widening of the QRS complex Arrthymias

Trend – patternLook at previous values GFR , creatinine As discussed consider pseudohyperkalaemia if isolated rise in serum K + or unexpected result Arrange for an urgent repeat if level > 6.0 mmol /L If repeat shows a rapid rise in K + for e.g > 0.5 mmol in 24 hrs – arrange admission

Clinical situation Check for clinical symptoms for e.g
○ lethargy
○ nausea
○ muscle weakness
○ paraesthesia Is the patient in urinary retention ? Acidosis e.g diabetic ketoacidosis AKI or CKD Review prescribed medications Urine output h/o severe trauma ? rhabdomyolysis- consider this is patients who
○ have laid immobile for uncertain period of time ( atleast + 1 hour )
○ have taken drugs like cocaine , ecstasy or heroin
○ intensive exercise + heat exhaustion
○ septic patients

Medication related hyperkalaemia is common Commonly used medications implicated are
○ ACE inhibitors
○ ARBs
○ NSAIDs
○ Aspirin
○ Potassium sparing diuretics
○ Aldosterone receptor antagonists
○ Beta blockers
○ Potassium containing laxatives as Movicol and fybogel
○ Heparin and LMWH If suspected withold the medication and repeat test in 1-2 weeks

Emergency treatment-Protect the heart Shift K+ out of cells Remove K+ from body Monitor K+ and glucose Prevent recurrence

LINKS AND RESOURCES

PATIENT INFORMATION

NHS on potassium tests https://www.nhs.uk/conditions/potassium-test/

A superb presentation for patients from Kidneyfund.org- American Kidney Foundation about hyperkalemia https://www.kidneyfund.org/kidney-disease/chronic-kidney-disease-ckd/complications/high-potassium-hyperkalemia.html

For patients who are advised a low potassium diet by Kidney Care and The Renal Association https://renal.org/wp-content/uploads/2017/06/KCUK-Potassium_web.pdf

A complete patient education resource on potassium and kidneys by the National Kidney Foundation https://www.kidney.org/sites/default/files/01-10-7269_ABG_PatBro_Hyperkalemiap7.pdf

Brilliant work for patients by The American Heart Association with a downloadable leaflet https://www.heart.org/en/health-topics/heart-failure/treatment-options-for-heart-failure/hyperkalemia-high-potassium

American Association of Kidney Patients has a useful page for patients with raised potassium https://aakp.org/center-for-patient-research-and-education/hyperkalemia/

 

INFORMATION FOR CLINICIANS ON HYPERKALEMIA

Best Practice in managing hyperkalaemia in CKD by National Kidney Foundation https://www.kidney.org/sites/default/files/02-10-7259%20Hyperkalemia%20Tool.pdf 

Emergency management of hyperkalaemia in adults by the Renal Association https://renal.org/wp-content/uploads/2017/10/HYPERKALAEMIA-ALGORITHM-MARCH-2014.pdf

ECG changes in hyperkalaemia from Emergency Medicine cases https://emergencymedicinecases.com/wp-content/uploads/2016/09/Episode-086-Sep2016-Hyperkalemia.pdf

Brilliant summary from Acadoodle on hyperkalemia ( must read ) https://acadoodle.com/articles/5-ecg-changes-of-hyperkalemia-you-need-to-know

Watch a 15 sec You Tube video on ECG changes https://www.youtube.com/watch?v=PxoRJN3SVZQ

European Society of cardiology-Third in a series on hyperkalemia: current views on the treatment of hyperkalemia Dr. Anjan Dasgupta https://www.escardio.org/Journals/E-Journal-of-Cardiology-Practice/Volume-14/fourteen-thirteen

 Beat the nephrologist ! – read the 104 page guideline ” Treatment of acute Hyperkalaemia in adultshttps://renal.org/guidelines/

 

 

References; Further reading Hyperkalemia : E Medicine http://emedicine.medscape.com/article/240903-overview Clinical Chemistry E- Book – William J Marshall , Stephen K Bangert , Marta Lapsley ; Hyperkalaemia Merck Manual Hyperkalaemia ;http://www.merckmanuals.com/
professional/endocrine-and-metabolic-disorders/
electrolyte-disorders/hyperkalemia Pathogenesis , diagnosis and management of Hyperkalaemia
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3061004/ Electrocardiogram manifestations in hyperkalaemia- available on
http://file.scirp.org/pdf/WJCD20120200002_21775315.pdf Treatment of acute Hyperkalaemia in adults ; Renal Association March 2014
http://www.renal.org/guidelines/joint-guidelines/
treatment-of-acute-hyperkalaemia-in-adults#sthash.9XJDQ8aK.dpbs Acid-base , fluids and electrolytes – Robert F Reilly , Jr.,Mark A.Perazella Making sense of ECG – Andrew R Houghton , David Gray Simon LV, Hashmi MF, Farrell MW. Hyperkalemia. [Updated 2019 Dec 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-.Available from: https://www.ncbi.nlm.nih.gov/books/NBK470284/ Pseudohyperkalaemia from acutetesting.org accessed via https://acutecaretesting.org/en/articles/pseudohyperkalemia , https://www.nbt.nhs.uk/sites/default/files/Hyperkalaemia%20in%20Primary%20Care.pdf

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