Acute
renal failure (ARF) refers to the rapid loss of renal function over days to
weeks. Chronic kidney disease (CKD)a , also called chronic renal insufficiency (CRI) by some, is
defined as a progressive loss of function occurring over several months to
years, and is characterized by the gradual replacement of normal kidney
architecture with interstitial fibrosis. Progressive kidney disease or
nephropathy is generally synonymous with CKD, and the two phrases are often
used interchangeably.
ETIOLOGY:-
Susceptibility
_
Advanced age
_
Reduced kidney mass and low
birth
weight
_
Racial/ethnic minority
_
Family history
_ Low
income or education
_
Systemic inflammation
_
Dyslipidemia
Initiation
_
Diabetes mellitus
_
Hypertension
_
Autoimmune disease
_
Polycystic kidney disease
_
Drug toxicity
Progression
_
Glycemia (among diabetic
patients)
_
Elevated blood pressure
_
Proteinuria
_
Smoking
C L I
N I C A L PRESENTATION OF CHRONIC KIDNEY D I S E A S E
GENERAL
CKD
development and progression is typically insidious in onset, often with the
absence of any noticeable symptoms.
At a
minimum, the diagnosis of CKD requires measurement of serum creatinine,
calculation of GFR and assessment of a urinalysis for urinary microalbumin or
total protein. The diagnosis of Stages 3, 4, and 5 CKD requires the work-up for
other common complications including anemia, cardiovascular risks, metabolic
bone disease, malnutrition, and disorders of fluids and electrolytes.
SYMPTOMS
Symptoms
are generally absent in CKD Stages 1 and 2, and may be minimal during Stages 3
and 4. Classic symptoms associated with Stage 5 CKD include pruritus,
dysgeusia, nausea, vomiting, and bleeding abnormalities. Symptoms associated with
anemia include cold intolerance, shortness of breath, and fatigue. The severity
of symptoms is related to the rate of anemia development and the degree of
hemoglobin reduction.
SIGNS
Cardiovascular:
Left ventricular hypertrophy, congestive heart failure, hyperhomocysteinemia,
dyslipidemia, palpitations, arrhythmias, electrocardiographic changes, elevated
creatine kinase-myocardial bound (CK-MB) and creatine kinase (CK), worsening
hypertension, and edema.
Musculoskeletal:
Cramping and muscle pain.
Neuropsychiatric:
Depression, anxiety, impaired mental cognition, fatigue, and sexual
dysfunction.
Gastrointestinal:
Gastroesophageal reflux disease, constipation, GI bleeding, nausea, and
vomiting.
LABORATORY
TESTS
Normal
or abnormal GFR with or without documented renal structural abnormalities;
presence of urinary albumin or
protein;
and pathologic assessment of kidney tissue.
Endocrine:
Increased sensitivity to insulin, secondary hyperparathyroidism, decreased
vitamin D activation, β2-
microglobulin
deposition, and gout.
Hematologic:
Anemia, iron deficiency, and bleeding.
STAGES OF CKD
STAGES
|
GFR in ml/min/1.73m2 body
surface area
|
1
|
>90
|
2
|
60-89
|
3
|
30-59
|
4
|
15-29
|
5
|
<15(including patient on dialysis)
|
PATHOPHYSIOLOGY
5 The various etiologic factors actually
damage the kidney in a heterogenous manner. For example, the key structural
lesion in diabetic nephropathy is glomerular mesangial expansion. In
hypertensive nephrosclerosis, it is hyalinosis of the kidney’s arterioles, and
in polycystic kidney disease it is the development and growth of renal cysts. A
variety of morphologic glomerular changes have been noted to occur, depending
on the primary diagnosis of the glomerulonephritis. The majority of progressive
nephropathies share a final common pathway to irreversible renal parenchymal
damage and ESKD.
The key elements of this pathway are:
(1) loss of nephron mass;
(2) glomerular capillary hypertension; and
(3)
proteinuria. The presence of or exposure to the initiation risk factors results
in loss of nephron mass. The remaining nephrons hypertrophy to compensate
for the loss of renal function and nephron mass. Initially this compensatory
hypertrophy may be adaptive. Yet over time the hypertrophy often becomes
maladaptive and leads to the development of glomerular hypertension, possibly
mediated by angiotensin II. Angiotensin II, a potent
vasoconstrictor of both the afferent and efferent arterioles, preferentially
affects the efferent arterioles, leading to increased pressure within the
glomerular capillaries. The development of intraglomerular hypertension
generally correlates with the development of systemic arterial hypertension.
Animal studies have demonstrated
that high intraglomerular capillary pressure impairs the
sizeselective function of the glomerular permeability barrier, and results in albuminuria and proteinuria. The resultant
proteinuria is thought to accelerate the progressive loss of nephrons due to
direct cellular damage. The filtered proteins consist of albumin, transferrin,
complement factors, immunoglobulins, cytokines, and angiotensin II, which have
varying molecular weights. Numerous studies have demonstrated that the presence
of these proteins in the renal tubule activate tubular cells which leads to the
upregulated production of inflammatory and vasoactive
cytokines, such as endothelin, monocyte chemoattractant protein (MCP-1),
and RANTES (regulated upon activation, normal T-cell expressed and secreted).
Accumulating evidence now suggests that intratubular complement
activation may be the key mechanism of damage
in the progressive proteinuric nephropathies.
Proteinuria is associated with the activation
of complement components on the apical
membrane of proximal tubules. These events eventually lead to scarring of the interstitium, and the
progressive loss of structural nephron units,
and ultimately function (reduced GFR).
Treatment:
Antihypertensive agent
|
MOA
|
Effect on renal hemodynamics
|
Diuretics
β-Adrenergic
blockers
Calcium
channel blockers
ACEI/ARB
Peripherally
acting antiadrenergic
drugs
|
Sodium
and volume depletion
↑Vasodilatory prostaglandin levels (IV
loop diuretics)
Renal
vasoconstriction (IV thiazide diuretics)
↓ Cardiac output
↑ Renal vascular resistance
(nonselective agents)
↓ Renal vascular resistance ( β1-selective
agents)
↓ Renal vascular resistance by
vasodilation of afferent
arterioles
(hypertensive patients)
Dilation
of the efferent arteriole
Direct
vasodilation (postsynaptic α1-adrenoreceptor blocking
agents)
|
Decrease
in GFR and RBF
Increase
in RBF
Decrease
in GFR and RBF
Decrease
in GFR and RBF
Decrease in GFR and RBF
No
change in GFR and RBF
Increase
in RBF and no change in GFR
Decrease
in GFR and no change in RBF
No
change in GFR and RBF
|
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