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Hypokalemia Estimated potassium requirements

Hypokalemia: Estimated potassium requirements


Potassium Deficit

Background

  • Potassium is the major intracellular cation with 98% of the total body potassium is in the intracellular compartment and only 2% located extracellularly (plasma).  The serum potassium level is a measure of the 2% that is  present in the extracellular space.
  • Hypokalemia is defined as a serum potassium concentration of less than 3.5 mEq/L [normal range: 3.5-5 mEq/L].
  • Hypokalemia classification:
    Mild (3-3.4 mEq/L)
    Moderate (2.5 - 2.9 mEq/L)
    Severe (< 2.5 mEq/L)
  • The patient's BMI has little effect when determining the amount of potassium required to reach a target level.  Conversely,  renal disease can profoundly impact the amount of potassium required.

Required Entries


Data points:



Current Potassium Level:   
       [Value below 3.9 mEq/L (mmol/L]


Target Potassium Level:    
       [Value below 3.9 mEq/L (mmol/L]


Renal function impaired?

 


heart

   




Old Rule of Thumb


10 mEq of potassium is required for each 0.10 mEq/L drop in serum [K+]



Updated Rules


10 mEq of potassium (IV/ oral) is required for each 0.13 mEq/L (mean value for oral and IV). decline in serum [K+] from the target level.
.
IV:   10 meq --> 0.14 mEq/L mean change. Oral: 10 meq --> 0.12 mEq/L mean change.



Key Reference top of page

Aboujamous H. et al. Evaluation of the Change in Serum Potassium Levels after Potassium Administration. J Clin Nephrol Ren Care 2016, 2:013.

  • Every 10 mEq of potassium increased serum potassium 0.13 mEq/L. Similar dose responses were seen whether IV or PO potassium was administered.
  • This study supports the common practice of administering 10 mEq of potassium for every 0.1 mEq/L desired increase in serum potassium.
  • It takes a significant loss in potassium stores to see a drop in serum potassium level (i.e., the extracellular space) due to this large amount of potassium in the intracellular space that helps to compensate for any loss.
  • Severe consequences of hypokalemia include cardiac arrhythmias, rhabdomyolysis, and muscle weakness that leads to respiratory depression or ileus. Chronic hypokalemia can cause increased ammoniagenesis, urinary concentration defects, polyuria, hypertension, acid base disorders, and hyperglycemia.
  • In examining the effect of BMI on the level of potassium repletion achieved per 10 mEq of potassium administered, the intravenous group had an increase in serum potassium ranging from 0.10 to 0.17 mEq/L per 10 mEq administered while patients that received oral potassium had a change in potassium that ranged from 0.12 to 0.13 mEq/L per 10 mEq with no discernable pattern across different BMI classifications.
  • The results further reveal that intravenous potassium appears to impact serum potassium levels similarly to the impact of oral potassium. Specifically, intravenous and oral potassium administration caused a mean 0.14 and 0.12 mEq/L increase in serum potassium level per 10 mEq administered, respectively.
  • There is no data to suggest that the degree of baseline hypokalemia will exponentially increase the amount of repletion necessary. Therefore, the lack of representation of patients with baseline moderate or severe hypokalemia is not thought to be a limitation to allowing the results of the study to be applied to patients with all degrees of hypokalemia.



References top of page

 

  1. Aboujamous et al. Evaluation of the Change in Serum Potassium Levels after Potassium Administration. J Clin Nephrol Ren Care 2016, 2:013,
  2. Asmar A, Mohandas R, Wingo CS. A Physiologic-Based Approach to the Treatment of a Patient With Hypokalemia. Am J Kidney Dis. 2012 September ; 60(3): 492–497.
  3. Cohn JN, Kowey PR, et al. New guidelines for potassium replacement in clinical practice: A contemporary review by the National Council on Potassium in Clinical Practice. Arch Intern MED/VOL 160, SEP 11, 2000.
  4. Gennari FJ. Disorders of potassium homeostasis: Hypokalemia and hyperkalemia. Crit Care Clin. 2002;18(2):273-288.
  5. Gennari FJ. Hypokalemia. N Engl J Med. 1998;339(7):451-458.
  6. Kamel KS, Quaggin S, Scheich A, et al. Disorders of potassium homeostasis: an approach based on pathophysiology. Am J Kidney Dis 1994;24:597–613.
  7. Kardalas E, et al. Hypokalemia: a clinical update. Endocrine Connections (2018) 7, R135–R146.
  8. Kim GH, Han JS. Therapeutic approach to hypokalemia. Nephron. 2002;92(suppl 1):28-32.
  9. Lippi G, Favaloro EJ, Montagnana M, Guidi GC. Prevalence of hypokalaemia:the experience of a large academic hospital. Intern Med J. 2010;40(4):315-316.
  10. Rastergar A, Soleimani M. Hypokalaemia and hyperkalaemia. Postgrad Med J 2001;77:759–764.
  11. Viera AJ, Wouk N. Potassium Disorders: Hypokalemia and Hyperkalemia.Am Fam Physician. 2015;92(6):487-495.
  12. Weiner ID, Wingo CS. Hypokalemia-consequences, causes, and correction. J Am Soc Nephrol. 1997;8(7):1179-1188.
Hypokalemia Estimated potassium requirements