Acute Kidney Injury

Definition

Sudden Reduction in renal function, leading to the retention of products normally excreted by the kidney

Prerenal

Inadequate delivery of blood to kidney to be filtered

Causes

Intravascular volume depletion: Vomiting, diarrhea, diuretics, cirrhosis, medications

Decreased cardiac output

Renal Arterial disease

Prsentation

Signs of intravasular volume depletion

Benign urine sediment

Oliguria

Renal

Cessation of renal function as a result of disease of the kidney

Acute Tubular Necrosis

Acute interstitial nephritis

Causes

Ischemic

Nephrotoxic

Prolonged prerenal injury

Anitbiotics
Cisplatin
IV contrast dye
NSAIDS
Calcineurin inhibitors
Hemoglobin
Myoglobin

Pathophysiology

Tubular Injury causes epithelial Cells to break down

Tamm-Horsfall mucoprotein is secreted by cells in ascending loop of henle

Formation of casts due to myoglobin and other metabolic products in distal tubules/collecting ducts of nephron

TGF Function

NaCl resoption is impaired so MD sees higher NaCl

Activation of TGF

Afferent arteriolar vasoconstriction

Reduction of GFR, and tubule flow rate

image

Recovery

More likely to reocver if baseline is normal

Mortality associated with ATN

Presentation

AKI 1-2 weeks following exposure
Fever
Rash
Eosinophiia
Urinalysis showing WBCs, RBCs, WBC casts

Causes

Drugs

Antibiotics
PPI
Nsaids
Phenytoin
Allopurinol
Ranitidine

Infection

EBC
CMV
Legionella
Bucella
Mycoplasma

Glomerularnephritides

Examples

Vasculitis
IgA nephropathy

Presentation

Systemic symptoms
Rapid rise in creatinine
HTN
Urinalysis showing RBC, RBC casts, protein

Post-renal

Causes

Congenital

Posterior urethral valves, meningomyelocele

Tumour

Prostate CA, Bladder CA, Cervical CA

Urologic

Papillary necrosis
Bilateral kidney stones
Bladder stones
Strictures

Neurogenic Bladder

Retroperitoneal fibrosis

Hyperkalemia

Maintenance of excretion is impaired when GFR decreases

Normal Function

Reabsorption in proximal tubule

Secretion in the cortical collecting

K+ is freely filtered across glomerulus

Treatment

Dialysis

Indications

A -Acidosis
E - Electrolyte
I - Intoxication
O - Overload
U - Uremia