Acute kidney injury

From Citizendium, the Citizens' Compendium

Acute kidney injury, previously called acute renal failure, is defined as as "An abrupt (within 48 hours) reduction in kidney function currently defined as an absolute increase in serum creatinine of more than or equal to 0.3 mg/dl (≥ 26.4 μmol/l), a percentage increase in serum creatinine of more than or equal to 50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria of less than 0.5 ml/kg per hour for more than six hours)."^[1]

Contents 1 Classification 1.1 Prerenal 1.2 Intrarenal 1.3 Post-renal 2 Treatment 2.1 Renal replacement therapy 3 Prevention 4 References 5 See also

Classification

Prerenal

Fractional excretion of sodium and urea for diagnosing transient AKI^[2]

Patients	Sensitivity	Specificity
Fractional excretion of sodium ≤ 1%
Receiving diuretics	58%	81%
No diuretics	78%	75%
Fractional excretion of urea ≤ 35%
Receiving diuretics	79%	33%
No diuretics	48%	75%

This is characterized by:

• Urinary sodium < 15 mmol/liter^[3]
• Fractional excretion of sodium in the urine of < 1% ^[2][3][4]
• Fractional excretion of urea nitrogen < 35%. ^[2][3]
• Ratio of urinary to plasma creatinine of > 20.^[3]

Causes include:

• Hypovolemia
• Hepatorenal syndrome
• Vascular disease

Intrarenal

Also simply called 'renal', this is characterized by fractional excretion of sodium in the urine of > 1%.^[4] Causes include:

• Glomerulonephritis (GN). This is characterized by significant proteinuria, red cells in the urine (possibly dysmorphic in appearance), and red-cell casts.^[5] GN may be caused by vasculitis.
• Acute tubular necrosis (ATN). ATN is characterized by pigmented granular casts in the urine sediment.^[5] Causes of ATN include radiocontrast media and non-steroidal anti-inflammatory agents.
• Interstitial nephritis.
• Drug induced. Many drugs can cause acute kidney injury. Vancomycin is associated with acute kidney injury if trough levels are above 15 microg/mL.^[6]

Post-renal

This is characterized by symptoms of obstruction and sometimes by anuria.

Treatment

The underlying cause of the kidney injury should be treated. Diuresis has been investigated as a nonspecific treatment, but no benefit was found.^[7]

If fluid resuscitation is used, the type of fluid probably does not matter according to a meta-analysis of randomized controlled trials by the Cochrane Collaboration.^[8]

Renal replacement therapy

For more information, see: Renal replacement therapy.

Renal replacement therapy may be used as treatment for acute kidney injury although the optimal intensitivy is unclear.^[9]

Prevention

Administration of atrial natriuretic peptide prior to major surgery may reduce acute kidney injury.^[10]

Various treatments may reduce contrast-induced nephropathy.

References

1. ↑ Mehta RL, Kellum JA, Shah SV, et al (2007). "Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury" 11 (2): R31. DOI:10.1186/cc5713. PMID 17331245.
2. ↑ ^{2.0 2.1 2.2} Pépin MN, Bouchard J, Legault L, Ethier J (October 2007). Diagnostic performance of fractional excretion of urea and fractional excretion of sodium in the evaluations of patients with acute kidney injury with or without diuretic treatment. Am. J. Kidney Dis. 50 (4): 566–73. DOI:10.1053/j.ajkd.2007.07.001. PMID 17900456.
3. ↑ ^{3.0 3.1 3.2 3.3} Steinman TI, Samir AE, Cornell LD (August 2008). Case records of the Massachusetts General Hospital. Case 27-2008. A 64-year-old man with abdominal pain, nausea, and an elevated level of serum creatinine. N. Engl. J. Med. 359 (9): 951–60. DOI:10.1056/NEJMcpc0804600. PMID 18753652.
4. ↑ ^4.0 4.1 Miller TR, Anderson RJ, Linas SL, et al (1978). "Urinary diagnostic indices in acute renal failure: a prospective study". Ann. Intern. Med. 89 (1): 47–50. PMID 666184.
5. ↑ ^5.0 5.1 Rabb H, Colvin RB (2007). "Case records of the Massachusetts General Hospital. Case 31-2007. A 41-year-old man with abdominal pain and elevated serum creatinine". N. Engl. J. Med. 357 (15): 1531–41. DOI:10.1056/NEJMcpc079024. PMID 17928602.
6. ↑ Hidayat LK, Hsu DI, Quist R, Shriner KA, Wong-Beringer A (2006). "High-dose vancomycin therapy for methicillin-resistant Staphylococcus aureus infections: efficacy and toxicity". Arch. Intern. Med. 166 (19): 2138–44. DOI:10.1001/archinte.166.19.2138. PMID 17060545.
7. ↑ Ho KM, Sheridan DJ (2006). "Meta-analysis of frusemide to prevent or treat acute renal failure". BMJ 333 (7565): 420. DOI:10.1136/bmj.38902.605347.7C. PMID 16861256.
8. ↑ Perel P, Roberts I (2007). "Colloids versus crystalloids for fluid resuscitation in critically ill patients". Cochrane Database Syst Rev (4): CD000567. DOI:10.1002/14651858.CD000567.pub3. PMID 17943746.
9. ↑ VA/NIH Acute Renal Failure Trial Network, Palevsky PM, Zhang JH, O'Connor TZ, Chertow GM, Crowley ST, Choudhury D, Finkel K, Kellum JA, Paganini E, Schein RM, Smith MW, Swanson KM, Thompson BT, Vijayan A, Watnick S, Star RA, Peduzzi P. Intensity of renal support in critically ill patients with acute kidney injury. N Engl J Med. 2008 Jul 3;359(1):7-20. Epub 2008 May 20. PMID 18492867
10. ↑ Nigwekar SU, Navaneethan SD, Parikh CR, Hix JK (February 2009). Atrial natriuretic peptide for management of acute kidney injury: a systematic review and meta-analysis. Clin J Am Soc Nephrol 4 (2): 261–72. DOI:10.2215/CJN.03780808. PMID 19073785.

See also

• Chronic kidney disease