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FACT SHEET: Acute Kidney Failure (also known as “AKF”, “acute renal failure” [ARF], and acute kidney injury [AKI])

Date of Publication: October 14, 2020

Note: Chronic kidney disease/failure are addressed in the Chronic Kidney Disease Fact Sheet and the Kidney Disease and Kidney Failure Advisory. Kidney transplantation is more fully addressed in the Organ Transplantation Fact Sheet.

Is the initiation of non-invasive dental hygiene procedures* contra-indicated?

  • Yes. Acute kidney failure/injury should be considered a medical emergency, for which immediate medical care is indicated.

Is medical consult advised?  

  • Yes, if acute kidney failure/injury is newly suspected.
  • Yes, if acute kidney failure/injury exists.

Is the initiation of invasive dental hygiene procedures contra-indicated?**

  • Yes. Acute kidney failure/injury should be considered a medical emergency, for which immediate medical care is indicated. 

Is medical consult advised? 

  • See above. Additionally:
    • Yes, for patients/clients receiving dialysis (e.g., about antibiotic prophylaxis and bleeding risk) or for those for whom kidney transplantation has occurred or is planned (e.g., about immunosuppression and infection considerations). It is also advised for patients/clients in whom the dental hygienist suspects severe or medically unaddressed deteriorating kidney function.

Is medical clearance required? 

  • Yes, for patients/clients who have, or have recently experienced, acute kidney failure/injury. 
  • Yes, for patients/clients receiving hemodialysis. The dental hygienist should confirm with the nephrologist that the patient/client is medically stable to receive dental hygiene (and dental) treatment, as well as ascertain if antibiotic prophylaxis is indicated. Hemoglobin and hematocrit levels, white blood cell count, platelet count, and coagulation tests may be indicated. 
  • Yes, for patients/clients who have undergone, or are about to, undergo kidney transplantation

Is antibiotic prophylaxis required?  

  • Possibly, particularly if the patient/client has received a kidney transplant, or if the patient/client is receiving hemodialysis. In dialysis situations, antibiotic prophylaxis may be indicated to prevent either infective endocarditis or infection of the dialysis access1

Is postponing treatment advised?

  • Yes. Patients/clients with ARF are typically not suitable for elective dental/dental hygiene care. 
  • In most circumstances, treatment should be postponed until kidney function has been restored to non-failure levels2 following resolution of the underlying cause, or at least until the patient/client is medically stable and has been medically cleared. 
  • For patients/clients undergoing hemodialysis, dental hygiene (and dental) treatment should be avoided after hemodialysis on the same day (especially within the first 6 hours afterward), because complications are associated with the use of anticoagulants (e.g., heparin) administered during dialysis therapy. Invasive procedures should be postponed until the day after dialysis. If a new dialysis access shunt is being placed in the patient/client, then dental hygiene treatment should be postponed two weeks. No dental/dental hygiene treatment should be performed if there is any infection or clotting at the site of the shunt. 
  • For patients/clients who have, or are about to receive, a kidney transplant, professional oral healthcare should be individually tailored to the patient/client. As a general principle, elective dental hygiene (and dental) treatment should be avoided for 3 to 6 months post-transplant.

Oral management implications

  • Compared with chronic kidney disease/failure , the dental hygienist is much less likely to encounter a patient/client with acute kidney failure.3 
  • Acute kidney failure/injury should be considered a medical emergency, for which immediate medical care is indicated. (See above.) 
  • In most circumstances, dental hygiene treatment should be deferred until the patient/client has recovered kidney function to non-failure levels. (See above.) 
  • While uremic stomatitis usually resolves after uremia is successfully treated, lesion healing can be assisted by dilute hydrogen peroxide gargles several times daily.

Oral manifestations

  • Because acute renal failure/injury is characterized by rapid onset, many of the oral manifestations seen in chronic kidney disease/failure are unlikely to be present. Also, oral findings which are present may be primarily related to the underlying cause(s) of, or risk factor(s) for, ARF (e.g., lupus, scleroderma, multiple myeloma, diabetesliver disease, etc.) rather than ARF itself. 
  • Halitosis and metallic taste in the mouth may occur.
  • Depending on the severity of acute kidney injury and antecedent health status of the patient/client, anemia may manifest as oral pallor. As well, bleeding can result from uremic platelet dysfunction.
  • Uremic stomatitis is a rare condition associated with ARF and blood urea nitrogen levels greater than 19.6 mmol/L (55 mg/dL). Early changes include red, burning mucosa covered with gray exudates followed by frank ulceration. Adherent white patches called “uremic frost”4 may be seen on the oral mucosa, and they may resemble hairy leukoplakia.

Related signs and symptoms

  • Acute kidney failure is characterized by a sudden and significant reduction in glomerular filtration rate (GFR)5 lasting for hours or days. This results inability to maintain electrolyte, acid-base, and water balance. The underlying causes are classified as pre-renal (i.e., not enough blood flow to the kidneys), intrinsic renal (i.e., direct damage to the kidneys themselves), or post-renal (i.e., urine backed up in the kidneys). Usually, renal function is restored once the underlying cause has been resolved, although permanent kidney damage may result with consequent end-stage renal disease6 or progression to chronic kidney failure
  • Pre-renal causes of AKF include: severe hypotension (“shock”); gastrointestinal losses of fluid (e.g., severe diarrhea or vomiting); excessive perspiration; severe dehydration; heavy blood loss; sepsis; severe burns with fluid sequestration; kidney losses of fluid (e.g., from diuretic overuse or diabetic ketoacidosis); blood pressure medications; myocardial infarction; heart failure; liver failure; use of acetylsalicylic acid (ASA) or non-steroidal anti-inflammatory medications (NSAIDS, including ibuprofen, naproxen, etc.); severe allergic reactions (anaphylaxis); and major surgery.  
  • Intrinsic renal causes of AKF include: blood clots in the veins and arteries in and around the kidneys; cholesterol deposits that block blood flow in the kidneys; severe glomerulonephritis7; acute tubular necrosis8; severe cortical necrosis9; vasculitis; hemolytic uremic syndrome10; thrombotic thrombocytopenic purpura11; infections (i.e., direct infection of renal parenchyma or associated with systemic infections, including the virus that causes coronavirus disease 2019 [Covid-19]); lupus; scleroderma; malignant hypertension; allergic interstitial nephritis12; rhabdomyolysis13; multiple myeloma; and tumour lysis syndrome14
  • Post-renal causes of AKF include: bilateral ureteral obstruction (or ureteral obstruction in patients/clients with a single kidney) by kidney stones or other cause; bladder obstruction (e.g., by bladder cancer); bladder rupture; urethral obstruction (e.g., by enlarged prostate or prostate cancer); damage to the nerves controlling the bladder; and blood clots in the urinary tract.15
  • AKF develops rapidly, usually in less than a few days. It almost always occurs in conjunction with another medical condition or event. Risk factors include: hospitalization (particularly in critically ill persons whose conditions require intensive care); advanced age; COVID-19 infection16; peripheral artery disease; high blood pressure; diabetes; heart failure; pre-existing kidney diseases; liver diseases; and certain cancers and their treatments.  
  • AKF can be fatal, and it often requires intensive treatment. This may include urgent dialysis treatment for a period of time. However, depending on the cause and the underlying health of the patient/client, it is often reversible with recovery of normal or near normal kidney function.
  • The signs/symptoms of acute kidney failure may differ from those of chronic kidney disease/failure, and they often depend on the underlying cause. 
  • Signs/symptoms of AKF include: decreased urine output (although occasionally urine output remains normal or is increased); fluid retention, with swelling of feet, ankles, and/or legs; dyspnea (shortness of breath; in the case of AKF usually caused by build-up of fluid in the lungs); fatigue; nausea; confusion; changes in mental status or mood; weakness; cardiac dysrhythmia (manifesting as irregular heartbeat); chest pain/pressure17; flank pain; muscle weakness (due to the body’s fluids and electrolytes being out of balance); hand tremor; unusual bleeding; persistent hiccups; decreased sensation, especially in hands or feet; and seizures, coma, and even death in severe cases.
  • Uremic frost may be seen on the skin.
  • AKF sometimes causes few or no overt signs/symptoms, and it is instead first detected through laboratory tests done for some other reason.

References and sources of more detailed information

Date: August 8, 2020
Revised: April 2, 2024


1 In hemodialysis, access is vascular, typically via a surgically created arteriovenous fistula or graft placed in the forearm. (In peritoneal dialysis, access is via a surgically placed abdominal catheter.) Notably, on the basis of apparently low risk associated with oral bacteria, the American Heart Association’s 2003 guidelines do not include a recommendation for prophylactic antibiotics before invasive dental procedures are performed on patients with intravascular access devices to prevent infective endocarditis or endarteritis except if an abscess is being drained.
2 Kidney function can be assessed by a variety of tests, including glomerular filtration rate (GFR), blood urea nitrogen (BUN), and serum creatinine. The severity of acute kidney injury is usually determined based on maximum serum creatinine concentration. Acute kidney injury is defined by the Kidney Disease: Improving Global Outcomes (KDIGO) Consensus Group as an increase in the concentration of serum creatinine of 26.5 umol/L (0.3 mg/dL) or more or 50% or more of the baseline within a 48-hour period or within 7 days after hospitalization or a decrease in urine output of < 0.5 mL/kg/h for 6 hours.
3 Having said this, ARF is not rare. In the United States, because of an aging population and increasing prevalence of hypertension and diabetes mellitus, from 2005 to 2014, the number of hospitalizations with a principal diagnosis of acute kidney injury increased from 281,500 to 504,600, and the number of hospitalizations with a secondary diagnosis of acute kidney injury increased from 1 million to 2.3 million. (Reference: Mercado MG et al.) In 2020, for the first time in 10 years, the rate hospitalization with AKI declined in the Medicare Fee-For-Service (FFS) population. (Reference: U.S. Dept. of Health and Human Services)
4 Uremic frost in the oral cavity is caused by urea crystal deposition on epithelial surfaces after evaporation of saliva.
5 Degree of renal function is usually measured and monitored by glomerular filtration rate, which is an expression of the quality of glomerular filtrate created each minute in the kidney’s nephrons. A GFR < 15 mL/min per 1.73 m<sup>2</sup>, if not reversible, indicates end-stage renal disease, in which a patient/client is unable to survive without dialysis; typically, this equates to < 15% kidney function.
6 End-stage renal disease (ESRD) results from near-total or total kidney failure, which leads to death unless hemodialysis, peritoneal dialysis, or kidney transplantation is undertaken.
7 Glomerulonephritis is inflammation of the glomeruli (tiny filters) of the kidney.
8 Acute tubular necrosis (ATN) is acute damage to the tubules (which filter out waste products and fluid) of the glomeruli of the kidney. ATN usually occurs as a result of a lack of oxygen and blood flow to the kidneys, such as may occur secondary to myocardial infarction, diabetes, and stroke. It may also occur as a result of chemical damage to the tubules, such that caused by some medications (including certain chemotherapy drugs, antibiotics, anaesthesia drugs, and dyes used during imaging tests) and toxins (such as alcohol, heavy metals, and cocaine, which may also damage the kidneys by other mechanisms).
9 Renal cortical necrosis is the death of the tissue in the outer part of the kidney (cortex) that results from blockage of the small arteries that supply blood to the cortex. Usually the cause is a major, catastrophic disorder that greatly decreases blood pressure.
10 Hemolytic uremic syndrome (HUS) is a condition when an immune reaction causes premature destruction of red blood cells (as well as platelets) that, in turn, block the kidney’s filtering system.
11 Thrombotic thrombocytopenic purpura (TTP) is a rare blood disorder where blood clots form in small blood vessels throughout the body, including the kidneys.
12 Allergic interstitial nephritis is inflammation and swelling in the spaces between the kidney tubules caused by allergic reaction, as may result from drug allergy.
13 Rhabdomyolysis is the breakdown of damaged skeletal muscle, which leads to release of myoglobin, the breakdown of which can cause kidney damage.
14 Tumour lysis syndrome is breakdown of tumour cells, which leads to release of toxins that can cause kidney damage.
15 Colon cancer and cervical cancer, given their proximity to the urinary tract, can also cause obstructive acute kidney injury
16 COVID-19 infection may lead to acute kidney failure/injury via various processes. These include systemic immune and inflammatory responses induced by viral infection, systemic tissue hypoxia, local immunothrombosis causing hypoxia, reduced kidney perfusion, endothelial damage, and direct epithelial infection with SARS-CoV-2.
17 The pericardium (lining around the heart) may become inflamed (pericarditis).

* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.