Diabetic Kidney Disease Flashcards
Diabetic Kidney Disease
Epidemiology
DKD is the most common primary diagnosis for patients who start dialysis (~50%)
Diabetic Kidney Disease
Epidemiology
60%: classic DKD (large kidneys, proteinuria > 1 g/d, ± diabetic retinopathy)
25% to 30%: another primary kidney disease in addition to DKD
Diabetic Kidney Disease
Epidemiology
10% to 15%: atypical presentation with ischemic nephropathy (low level proteinuria)
Diabetic Kidney Disease
Epidemiology
Kidney diseases in diabetic patients who present with ESRD:
Cumulative prevalence of proteinuria is ~50% to 60% at 25 years after diagnosis of diabetes.
Cumulative prevalence of progression to ESRD is ~60% at 5 years after onset of proteinuria.
Cumulative prevalence of proteinuria and progression to ESRD are similar for DM types 1 and 2.
Diabetic Kidney Disease
Risks for the Development of DKD and Progression
Unmodifiable risks:
Genetic susceptibility:
Family history of predisposition to abnormal sodium handling and hypertension
Genotypes: angiotensin-converting enzyme (ACE), angiotensin II type 2-receptor, aldose reductase
Diabetic Kidney Disease
Risks for the Development of DKD and Progression
Unmodifiable risks:
Genetic susceptibility:
Ethnicity: Blacks, Hispanics, Pima Indians with DM type 2
Gender: Caucasian males and African American females
Age: possibly early onset
Duration of DM
Modifiable risks: hypertension, early glomerular hyperfiltration, prolonged uncontrolled hyperglycemia, obesity, tobacco smoking, use of oral contraceptives
Diabetic Kidney Disease
Clinical Manifestations
Albuminuria:
Moderate increase in albuminuria may predict high risk for eventual DKD
Diabetic Kidney Disease
Clinical Manifestations
The American Diabetes Association recommends screening for microalbuminuria in:
All patients with DM type 2 at the time of diagnosis and annually thereafter
All patients with DM type 1 five years after the diagnosis and annually thereafter
Diabetic Kidney Disease
Clinical Manifestations
(Microscopic) Hematuria:
May occur with DKD
Red blood cell casts may be present, but other glomerular diseases must be ruled out.
Diabetic Kidney Disease
Clinical Manifestations
Morbidities and mortality:
Increasing albuminuria and decreasing GFR correlate with cardiovascular and renal events in patients with DM type 2.
Mortality among diabetics with ESRD is 1.5 to 2.0-fold greater compared to non-diabetics
Diabetic Kidney Disease
Natural History
Proposed scheme of DKD stages for type 1 DM (less reliable for type 2 DKD):
Pre-DKD: 0 to 5 years since disease onset: glomerular hyperfiltration, renal hypertrophy
Diabetic Kidney Disease
Natural History
Incipient DKD: 5 to 15 years
Microalbuminuria (30 to 300 mg/24 h or overnight albuminuria at 20 to 200 μg/min in at least two of three consecutive nonketotic sterile urine samples) occurs in 20% to 30% of patients, less than 50% of whom will progress to overt nephropathy, hypertension.
Diabetic Kidney Disease
Natural History
Incipient DKD: 5 to 15 years
Structural changes: mesangial expansion, moderate glomerular basement thickening, arteriolar hyalinosis
Diabetic Kidney Disease
Natural History
Overt DKD: 15 to 25 years:
Proteinuria (>300 mg albuminuria/24 hours or overnight albuminuria > 200 μg/min—when severely increased albuminuria occurs, the majority will progress to ESRD), nephrotic syndrome, reduced glomerular filtration
Diabetic Kidney Disease
Natural History
Overt DKD: 15 to 25 years:
Structural changes: severe glomerular basement membrane thickening, mesangial nodules (Kimmelstiel–Wilson lesions), tubulointerstitial fibrosis
Diabetic Kidney Disease
Natural History
ESRD > 25 years: 4% to 17% at 20 years from time of diagnosis of type 1 DM
Diabetic Kidney Disease
Pathogenesis
Hyperglycemia:
Enhances matrix production, glycation of matrix proteins, formation of advanced glycation end (AGE) products
Stimulates VEGF, endothelial injury
Increases expression of transforming growth factor β (TGF-β)
Diabetic Kidney Disease
Pathogenesis
Advanced glycation end products:
AGE crosslinking with collagen
AGE:AGE receptor interaction (AGE:RAGE) leads to oxidative stress, activation of protein kinase C (PKC)
Diabetic Kidney Disease
Pathogenesis
Activation of PKC pathway leading to:
Endothelial dysfunction with decreased NO production
Increased expression of ET1, VEGF, NFκB, and plasminogen activator inhibitor-1 (PAI-1) leading to tissue inflammatory response, TMA, vascular injury
Diabetic Kidney Disease
Pathogenesis
Polyol pathway (via aldose reductase): thought to contribute to diabetic complications including diabetic cataracts, neuropathy, hyperfiltration, albuminuria. Use of aldose reductase inhibitors have been disappointing due to hypersensitivity reactions and liver abnormalities.
Diabetic Kidney Disease
Pathogenesis
Accumulation of N-acetylglucosamine via hexosamine pathway: N-acetyleglucosamine may lead to increased synthesis of TGF-β1, PAI-1.
Diabetic Kidney Disease
Pathogenesis
Prorenin activation of mitogen-activated protein kinases
Reduction of nephrin expression presumably via angiotensin II
Diabetic Kidney Disease
Pathogenesis
Systemic hypertension
Metabolic stress leading to mitochondrial dysfunction (which may lead to type B lactic acidosis observed in patients with diabetic ketoacidosis)
Diabetic Kidney Disease
Pathogenesis
Structural Changes
Gross structural changes: kidney weight increases by ~15% due to glomerular hypertrophy and hyperfiltration
Diabetic Kidney Disease
Pathogenesis
Histopathology
Glomerular basement thickening (up to three times normal)
Diabetic Kidney Disease
Pathogenesis
Histopathology
Mesangial expansion:
Due in part to hyperglycemia induced increased matrix production or glycation of matrix proteins, AGE crosslinking with collagen, and decreased matrix degredation.
Mild to severe diffuse mesangial expansion without nodules
Diabetic Kidney Disease
Pathogenesis
Histopathology
Nodular glomerular intercapillary lesions (Kimmelstiel–Wilson lesion):
Associated with mesangiolysis and capillary microaneurysms
Differential diagnoses of nodular glomerulosclerosis: dysproteinemias (e.g., amyloidosis and monoclonal Ig deposition diseases, and immunotactoid GN), fibronectin glomerulopathy, collagen III glomerulopathy, chronic hypoxic/ischemic conditions, chronic MPGN, or idiopathic.
Diabetic Kidney Disease
Pathogenesis
Histopathology
Nodular glomerular intercapillary lesions (Kimmelstiel–Wilson lesion):
Patients with Kimmelstiel–Wilson lesions are more likely to have diabetic retinopathy (DR) and worse kidney function.
Diabetic Kidney Disease
Pathogenesis
Histopathology
Advanced diabetic sclerosis
Vascular lesions including hyalinization of both afferent and efferent arterioles, pathognomonic for diabetic nephropathy, and arterial intimal fibrosis.
Diabetic Kidney Disease
Indications for Kidney Biopsy in Patients with DM
Absence of DR (particularly in DM type 1). Note, however, the absence of DR in DM type 2 does not exclude DKD.
Diabetic Kidney Disease
Indications for Kidney Biopsy in Patients with DM
NOTE
Patients with DM type 1 and DKD almost always have other evidence of diabetic microvascular disease (i.e., DR, neuropathy), but the converse is not true (i.e., not all patients with DR have DKD)