What is acute interstitial nephritis?
Inflammation of renal tubules & interstitium
What are some causes of acute interstitial nephritis?
– hypersensitivity reaction to drugs – infections – autoimmune diseases--SLE, Sjogren’s
How do drug induced cases of acute interstitial nephritis resolve?
Drug-related cases are usually reversible – idiosyncratic – recur with re-exposure – older patients particularly susceptible
How do we treat acute interstitial nephritis ?
• Most drug-related cases resolve when offending drug is discontinued • Treat associated infections • Treat the underlying cause in autoimmune disorders
What are morphological features of acute interstitial nephritis ?
– Inflammation and edema of interstitium with involvement of tubules (tubulitis) sparing glomeruli and vessels – Lymphocytes, plasma cells, eosinophils – May see granulomas
What is acute pyelonephritis?
Acute inflammation of the kidney due to a bacterial infection – urinary route: Usually gram negative bacilli – hematogenous route
Predisposing conditions to what disease? – urinary obstruction--congenital or acquired – urinary tract instrumentation – vesicoureteral reflux – pregnancy – diabetes
Where do you find the inflammatory cells in Pyelonephritis?
PMNs between the tubules but also within the tubules
Chronic renal failure results from direct tubular toxicity of light chains, tubular obstruction by casts and interstitial inflammation in 25% of pt with what disease?
Multiple Myeloma causes cast nephropathy how?
• Due to excessive production and urinary excretion of light chains • Factors that favor intratubular precipitation and cast formation: hypercalcemia, volume depletion & nephrotoxins
How does multiple myeloma present?
Presenting features: – older patients, usually over 40 – renal insufficiency & proteinuria – history of bone pain, fractures – hypercalcemia – monoclonal light chains in blood or urine
How does multiple myeloma look on LM, IF and EM?
• LM: Crystalline, fractured casts in tubules with associated cellular reaction
• IF: May see light chain predominance
• EM: Electron dense, fractured casts
How doe you treat myeloma cast nephropathy?
Acutely, hydration and urinary alkalinization to prevent tubular obstruction by casts & chemotherapy or stem cell transplantation
Acute interstitial nephritis is often caused by drugs and characterized by what?
interstitial inflammation with eosinophil predominance, eosinophilia, eosinophiluria
Pyelonephritis is ofen due to ascending UTI and characterized by what?
interstitial and tubular inflammation and the presence of bacteria on urine culture
Myeloma cast nephropathy occurs in patients with multiple myeloma and is characterized by what?
fractured tubular casts with either lambda or kappa light chain predominance
What is hypertensive nephrosclerosis?
Chronic kidney disease in a patient with long-standing, poorly controlled HTN & Proteinuria is often present
What are some morphologic features of hypertensive nephrosclerosis?
– Gross: Normal to slightly small with finely granular subcapsular surface
– LM: Subcapsular glomerular sclerosis, tubular atrophy, interstitial fibrosis, arteriolar hyaline
What causes renovascular hypertension?
Renal artery stenosis is a secondary cause of hypertension with 2 main causes: atherosclerosis & fibromuscular dysplasia
Other causes--trauma, dissection, extrinsic compression
What does renal artery stenosis cause hypertension?
decreased kidney perfusion causes the kidney activate the RAAS
When should you suspect renal artery stenosis?
– early or late onset HTN
– difficult to control HTN
– abdominal or flank bruit
– renal failure after starting ACE-inhibitor
How do you diagnose renal artery stenosis?
– CT with contrast
– Renal arteriography
– Doppler U/S
– Captopril renogram
– Renal vein renin sampling
BASICALLY IMAGE IT
What are some morphological features of renal artery stenosis?
Atherosclerosis & fibromuscular dysplasia ( usually younger women with intimal, medial and adventitial forms)
Where does fibromuscular dysplasia usually occur?
• Renal artery – 60-75% (bilateral – 35%)
• Cervicocranial arteries – 25-30%
• Visceral arteries – 9%
• Extremity arteries – 5%
Two vascular beds involved in up to 28%
What does medial fibroplasia of FMD usually look like?
• Alternating thinned media and thickened fibromuscular ridges
• Forms “string of beads” radiographically
• Beading is larger than caliber of artery
• Middle to distal artery
How do you treat renal artery stenosis?
– Surgical revascularization
– Angioplasty and stenting
– Medical management only
What do renal cortical infarcts look like?
• Renal artery occlusion – extensive parenchymal infarction
• Smaller branch=wedge-shaped infarct, Pale with hyperemic border, Coagulation necrosis & Hemorrhage and acute inflammation at edge
• Fibrotic (later)
What is atheroembolic disease and when does it occur?
• Disruption of atherosclerotic plaques can cause acute and subacute renal failure
• Occurs after procedures that disrupt plaques in the aorta, leading to a shower of cholesterol emboli that lodge in the renal microvasculature
What are the possible outcomes of an infarcted kidney?
– Stabilized or normal renal function in mild, isolated cases
– Chronic, progressive deterioration in renal function in subacute cases
– End-stage renal disease in severe cases
– Permanent dialysis may be necessary
Thromobotic microangiopathy is characterized by what?
Characterized by thrombosis in capillaries and arterioles
– Microangiopathic hemolytic anemia
– Thrombocytopenia (can have purpura)
– Renal failure
Hemolytic uremic syndrome occurs when?
Often occurs after intestinal infection with E. coli O157:H7
Renal artery stenosis can be caused by atherosclerosis or FMD and clinically presents as what?
resistant HTN or kidney dysfunction (often after ACE-I or ARB)
Atheroembolic disease causes acute and progressive renal dysfunction and often occurs when?
after arterial angiography & has histopathologic evidence of clefts in vascular lumen
What is chronic kidney disease?
• Progressive irreversible renal insufficiency that develops over months to years
• May ultimately lead to end-stage renal disease: Kidneys no longer function to maintain life (GFR<10 ml/min)
What are the main causes of CKD?
– Cystic diseases
What happens to kidney size in CKD?
Kidney size usually (but not always) reduced but normal or large kidneys may be seen with: Diabetes, Amyloidosis, HIV, Cystic kidney diseases
What can we see happen secondarily to CKD?
Anemia (decreased erythropoietin production occurs below GFR of 60 ml/min), Hypertension and 2° hyperparathyroidism (decreased renal synthesis of 1,25-dihydroxy-D3 and decreased phosphate excretion contribute to hypocalcemia,hyperphosphatemia, and renal osteodystrophy)
Other findings with CKD include?
– metabolic acidosis • decreased secretion of ammonium and retention of phosphates & sulfates
– inability to maintain sodium & water balance
– coagulopathy--platelet dysfunction
– sensorimotor neuropathy
CKD presents with physical symptoms of chronic uremia which are what?
– lethargy, fatigue
– day-night sleep reversal
– anorexia, nausea & vomiting
– restless legs syndrome
– uremic pericarditis
What are the management goals with CKD?
– preserve renal function and delay progression to end-stage renal disease
– prevent or minimize adverse effects
– institute renal replacement therapy when necessary
What can we do to slow the progression of CKD?
– Control hypertension (ACE-I, ARB)
– Reduce proteinuria
– Control blood sugar
– Smoking cessation
– Disease-specific therapy as indicated
What other things can we do to try to help CKD progression?
– Dietary restrictions: Na+, K+, phosphorus and protein?
– Control hyperlipidemia
– Correct anemia
– Correct acidosis
– Dialysis or kidney transplant when necessary usually GFR < 10
What is the most common cause of CKD and
ESRD in the US?
What does CKD result in?
– Metabolic acidosis
– Increased risk of hyperkalemia
– Secondary hyperparathyroidism • Due to phosphorus retention and impaired calcitriol production
– Anemia due to Epo deficiency
How is ESRD treated?
with dialysis or kidney transplantation