Acute Kidney Injury - Mini Lecture. Updated 02/2013. Quickly and easily identify and workup acute kidney injury. Objectives. The incidence of AKI is estimated at 1% of patients that present to the hospital and 7-50% of patients in the ICU.
Part of the initial history should be determining every patients baseline Cr.
May present as Uremia (malaise, anorexia, nausea, vomiting), but is usually asymptomatic.
Acute Kidney Injury Network (AKIN) Criteria
Look for patients with decreased PO, diarrhea, vomiting, tachycardia, orthostasis….
Order: UA, Uosm, Una, Ucr, BMP, Uurea (if on diuretics)
The kidney functions properly in patients with prerenal azotemia.
True volume depletion can be treated with normal saline.
Decreased effective arterial blood volume can be present in CHF, Cirrhosis or nephrotic syndrome. Treatment should focus on the underlying disease.
Usually occurs after an ischemic event or exposure to nephrotoxic agents.
Look for muddy brown casts and FeNa>2%
AIN - Acute Interstitial Nephritis
Classic presentation is fever, rash, eosinophilia and Cr bump 7-10 days after drug exposure.
Urine may show leukocytes, leukocyte casts and erythrocytes, cultures will be negative.
CIN - Contrast Induced Nephropathy
Increased Cr of 0.5mg/dl or 25% 48hrs after contrast administration.
Prevent with NS or isotonic fluid+sodium bicarb, hold NSAIDs, metformin and diuretics (in patients without fluid overload).
Others – Glomerular Disease, Pigmented Nephropathy, Thrombotic Microangiopathy
Intrinsic Kidney Diseases
Bladder outlet obstruction can be seen with bladder scan and relieved with catheterization
Ureteral obstruction and hydronephrosis may be seen on ultrasound and noncontrast CT
Order: Order: UA, Uosm, Una, Ucr, BMP, Uurea (if on diuretics)
Patients often have a history of pelvic tumors, irradiation, congential abnormalities, kidney stones, genitourinary, procedures or surgeries, and prostatic enlargement.
Today, his vitals are T-37, BP-110/55, HR-60, RR-16 and his Cr is 2.7, FeNa-2.3%, FeUrea-51%, UA shows trace protein and occasional Granular casts. UOP has been stable.
What is the most likely cause of his AKI?
A. Acute Interstitial Nephritis
B. Benign Prostate Hypertrophy
C. Acute Tubular Necrosis
D. Prerenal Azotemia
Monitor serum Cr for at risk patients
Make sure I/Os are recorded correctly
Diagnose as Prerenal, Intrinsic or Postrenal
Order routine labs including BMP, UA, Uosm, Ucr, Una (Urine Urea if on diuretics)
Imaging studies as necessary
Begin appropriate treatment
Stop offending agent
Fluids if appropriate
Renal dosing of meds
Take Home Points