Acute Kidney Injury 5 Flashcards
What is the primary cause of postrenal AKI?
Bilateral obstruction of the lower urinary tract or obstruction of a solitary kidney.
What are common congenital causes of postrenal AKI?
Posterior urethral valves and ureteropelvic junction obstruction.
What are common acquired causes of postrenal AKI?
Nephrolithiasis, blood clots, and tumors.
What is the pathophysiological mechanism of postrenal AKI?
Obstruction increases intratubular and Bowman’s space hydrostatic pressure, reducing the pressure gradient across glomerular capillaries and GFR.
How does unilateral obstruction differ from bilateral obstruction in postrenal AKI?
Unilateral obstruction is often asymptomatic due to compensatory function of the unaffected kidney, while bilateral obstruction causes significant renal dysfunction.
What prenatal findings suggest postrenal obstruction?
Ultrasound showing obstruction and complications like oligohydramnios.
What are complications of severe prenatal obstruction?
Pulmonary hypoplasia due to oligohydramnios.
What are key urinary symptoms in children with postrenal AKI?
Difficulty urinating, weak stream, and anuria.
What are additional clinical findings in postrenal AKI?
Abdominal or flank pain, gross hematuria, palpable bladder, or abdominal mass.
What is the first-line imaging for postrenal AKI diagnosis?
Renal ultrasound.
What is the role of voiding cystourethrogram in postrenal AKI?
To evaluate posterior urethral valves and ureteropelvic/ureterovesical junction obstruction.
What lab findings are typical in postrenal AKI?
BUN-to-creatinine ratio <10, urine osmolality <350 mOsm/kg, and FENa >1%.
What is the core treatment for postrenal AKI?
Relief of obstruction through catheter drainage or surgical intervention.
What is post-obstructive diuresis?
Polyuria and electrolyte abnormalities occurring after relief of obstruction.
Why does post-obstructive diuresis occur?
Altered sodium transporter expression, natriuretic factors, and impaired medullary gradient.
What electrolytes are commonly lost during post-obstructive diuresis?
Sodium, potassium, calcium, bicarbonate, and chloride.
How long does post-obstructive diuresis usually last?
Typically 24–36 hours but may persist for months in rare cases.
What fluid is used for replacement during post-obstructive diuresis?
0.45% saline, given at a rate slower than the urine output rate.
What are key monitoring parameters during post-obstructive diuresis?
Vital signs, volume status, urine output, and electrolytes.
What complications can arise from poor monitoring of post-obstructive diuresis?
Severe volume depletion, hypokalemia, hyponatremia, hypernatremia, and hypomagnesemia.
Why is renal ultrasound important in postrenal AKI?
It is the most sensitive and specific test for obstruction.
What is a medical emergency in postrenal AKI?
Obstruction in a solitary kidney or bilateral obstruction.
What are the main goals during the management of post-obstructive diuresis?
Avoiding severe volume depletion and correcting electrolyte imbalances.
How does creatinine clearance change after obstruction relief?
It improves rapidly during post-obstructive diuresis.
