AEIOU · Indications for Urgent Hemodialysis Mnemonic

Published: Sep 15, 2025
Author: Maria Giulia Boemi, MD•
Editor: Alyssa Haag, MD•
Editor: Ian Mannarino, MD, MBA•
Editor: Arianna Succi, MD•
Editor: Kelsey LaFayette, DNP, ARNP, FNP-C
Illustrator: Abbey Richard, MSc
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What is hemodialysis?

Hemodialysis is a form of renal replacement therapy in which a device assists the kidneys in maintaining homeostasis by removing excess fluid, solutes, and toxins from the blood. During hemodialysis, an intravenous line (IV) or an arteriovenous line (i.e., a connection between a small artery and vein, like an AV graft or AV fistula) is connected to a dialysis machine. The machine filters blood through a semipermeable membrane that separates it from a dialysis solution, allowing solutes to move from higher to lower concentrations. The dialysis solution is formulated to draw excess fluid and waste products from the blood for removal.  

Hemodialysis is typically used to treat rapid loss of kidney function (i.e., acute kidney injury), progressive loss of kidney function (i.e., chronic kidney disease) or the ingestion of certain toxic substances. It can be used short-term until the kidneys regain function or toxins are removed, long-term until a kidney transplant is available, or lifelong in those ineligible for renal transplantation. 

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What is AEIOU?

AEIOU is a mnemonic device used to help recall the urgent indications for hemodialysis. 

What does the “A” in AEIOU mean?

The “A” stands for acidosis. While acidosis is typically defined as a blood pH below 7.35, urgent dialysis is indicated when blood has a pH of 7.15 or less. The kidneys play a role in acid excretion and in the resorption and synthesis of bicarbonate (HCO3), which is alkalotic or basic. When kidney function is reduced, these processes can be impaired, leading to metabolic acidosis. Hemodialysis can alter the concentration bicarbonate in the blood to mitigate acidosis. 

What does the “E” in AEIOU mean?

The “E” stands for electrolyte imbalances, which mainly refers to hyperkalemia (i.e., high blood potassium levels). Hyperkalemia can alter cardiac cell function, and lead to life-threatening arrhythmias, or abnormal heart rhythms. Generally, potassium levels above 6-6.5 mEq/L may indicate the need for hemodialysis, especially if accompanied by EKG changes. Hemodialysis can alter the blood concentration of potassium (and other solutes) in the blood while also correcting acidosis, which contributes to hyperkalemia. 

What does the “I” in AEIOU mean?

The “I” represents ingestion or overdose of certain substances or medications. In these instances, hemodialysis can be used to either remove the toxin or as supportive therapy to alleviate its effects.   

Of note, the acronym, I STUMBLED, can be used to recall the dialyzable substances:  

What does the “O” in AEIOU mean?

The “O” stands for overload, which refers to volume overload. Impaired kidney function can lead to the accumulation of excess fluid, which can cause or exacerbate heart failure. Hemodialysis can reduce excess fluid by removing it in large volumes. 

What does the “U” in AEIOU mean?

The “U” stands for uremia, or the accumulation of urea in the blood. This can be detected by an increased level of blood urea nitrogen (BUN) in laboratory tests. Urea is a metabolic product of dietary and tissue protein breakdown and is predominantly excreted by the kidneys. When urea excretion is impaired, its blood levels rise and can cause platelet dysfunction and bleeding (i.e., uremic bleeding), inflammation of the pericardium (i.e., uremic pericarditis), and inflammation of brain tissue (i.e., uremic encephalitis). Therefore, the “U” may also stand for uremic pericarditis and uremic encephalitis.  

What are the most important facts to know about the AEIOU mnemonic?

Hemodialysis is a device designed to help the kidneys remove excess fluid, solutes, and toxins from the blood. It is used in situations of impaired renal function or after the ingestion of certain toxic substances or medications. The mnemonic “AEIOU” is used as a memory device to help recall the indications for urgent hemodialysis and stands for acidosis, electrolyte imbalance, ingestion or intoxication, overload of fluid, and uremia, respectively.  

Key Takeaways

Definition 

“AEIOU” is a mnemonic device used to help recall the urgent indications for hemodialysis.  

Hemodialysis

Hemodialysis is a form of renal replacement therapy in which a device assists the kidneys in maintaining homeostasis by removing excess fluid, solutes, and toxins from the blood. 

A 
 

Acidosis

E 

Electrolyte imbalances 

I 

Ingestion or overdose 

O 

Overload (of excess fluids)  

U 

Uremia  

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References

Cohen D, Valeri AM. Treatment of irreversible renal failure. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Elsevier; 2016:chap 131. 


King JD, Kern MH, Jaar BG. Extracorporeal removal of poisons and toxins. Clin J Am Soc Nephrol. 2019;14(9):1408-1415. doi:10.2215/cjn.02560319 


Kraut JA, Madias NE. Consequences and therapy of the metabolic acidosis of chronic kidney disease. Pediatr Nephrol. 2011;26(1):19-28. doi:10.1007/s00467-010-1564-4 


Lyman JL. Blood urea nitrogen and creatinine. Emerg Med Clin North Am. 1986;4(2):223-233. doi:10.1016/S0733-8627(20)30997-4 


Malhotra A. Acute kidney injury (AKI). Geriatric Trauma and Acute Care Surgery. 2017;367-380. Published 2017 Jul 28. doi:10.1007/978-3-319-57403-5_39