SAP - CKD Flashcards
Definition of CKD and prevalence.
CKD is defined as abnormalities of kidney structure or function, present for >3 months, with implications for health (KDIGO, 2012)
Kidney damage refers to a range of abnormalities observed during clinical and laboratory assessment.
criteria:
DECREASED GFR <60
Markers of kidney damage e.g. Albumin in urine Urine sediments Structural abnormalities detected by imaging Abnormalities detected by histology History of Kidney Transplantation
What is GFR?
Glomerular Filtration Rate (GFR) is the best marker of kidney function in health and disease = volume of plasma filtered by kidney per unit time.
We usually estimate the GFR using a prediction equation and serum creatinine.
Causes of CKD
- Pre renal
Any condition leading to persistently decreased renal perfusion e.g. Heart Failure - Renal causes
a. ) renal vascular disease –> Hypertensive Nephrosclerosis
- -> Renal Artery Stenosis
b. ) Glomerular disease –> Primary Glomerular Diseases – many examples –> Secondary Glomerular Diseases e.g. Diabetic Glomerulosclerosis
c. ) Tubular and interstitial disease
- -> Repeated Urinary Tract Infections, Reflux Nephropathy –> Drugs and Toxins - Post renal
Chronic Obstruction – any cause e.g. prostatic disease
UTI / drugs etc
Intrinsic Renal causes of CKD are divided into vascular causes, glomerular causes and problems with the tubular system.
Causes can be divided into primary renal defects (i.e. disease originating in the kidney), or secondary (i.e. kidney disease secondary to a systemic disease affecting multiple organs, such as Diabetes).
Primary Glomerular diseases include diseases such as Focal and Segmental Glomerulosclerosis.
According to USA data, what is the commonest cause of Chronic Kidney Disease? Hypertensive Nephrosclerosis Diabetic Nephropathy Primary Glomerular Diseases Reflux Nephropathy
Diabetic Nephropathy
then
High blood pressure
Causes of Chronic Kidney disease: Diabetic Nephropathy
Advanced CKD occurs in as many as 40% of diabetics.
Most common lesions involve the glomeruli and the arterioles.
Thickened GBM (Glomerular Basement Membrane) and increased mesangial matrix
There are four major histologic changes in the glomeruli in diabetic nephropathy:
mesangial expansion; glomerular basement membrane thickening; podocyte injury; and glomerular sclerosis
Diabetic Nephropathy: Microalbuminuria
The earliest evidence of protein leak is microalbuminuria.
It is the earliest marker of glomerular disease – appears before reduction in GFR
Measured as Albumin Creatinine ratio (ACR)
Clinically important proteinuria = ACR of >3mg/mmol
Classifying CKD
CKD should be classified according the Glomerular Filtration Rate and the level of albuminuria (i.e. protein leak) – both NICE and KDIGO recommend this.
G1, G2, G3a, G3b, G4, G5
G1 = >90 = normal, not CKD G2= 60-89 = normal, not CKD G3a =45-59 G3b = 30-44 G4 = 15-29 G5 = <15 = kidney failure
Classifying CKD by ACR:
A1, ACR <3
A2, ACR 3-30
A3, ACR >30
Causes of Chronic Kidney disease: Hypertensive Nephrosclerosis
In hypertensive patients, there is arteriosclerosis of the major renal arteries and changes in the intra-renal vasculature (Nephrosclerosis).
increased BP –> medial and intimal thickening, hyalanization of arteriolar walls –> Affected vessels have thickened walls, narrowed lumens leading to ischaemia. –> lesser blood reaching the AE, so decreased GFR –> causes increase in renin –> RAAS –> increase fluid retention –> increases HBP again -> repeating cycle
glomerular disease presentations
protein in the urine = nephrosis or blood and protein in the urine (nephritic).
Cause of CKD: Reflux Nephropathy
It leads to tubulointerstitial nephritis.
It results from a combination of VUR and infections.
Typically, there is papillary damage and cortical scarring as well.
Exmination findings of the CKD stage 5
Symptoms common when urea level exceeds 40 mmol/L:
Malaise
Loss of Appetite
Itching
Nausea
Symptoms associated with CKD complications
In uraemia associated with CKD Stage 5, symptoms can be more severe – mental slowing, seizures and myoclonic twitching
Pallor, brown discolouration of the nails, scratch marks due to uraemic pruritus, signs of fluid overload. Pericardial friction rub, flow murmurs
COMPLICATIONS OF CKD
Anaemia Bone Pain Cardiovascular disease Pericarditis Volume overload
COMPLICATIONS OF CKD Anaemia
Erythropoetin deficiency - CKD kidney cannot produce Epo which is needed to act on bone marrow to produce more RBC
There is also often haematinic deficiencies (B12, Folate, Iron) and Bone Marrow Toxins are retained in CKD.
Anaemia symptoms – Pallor, Lethargy and Shortness of Breath on exertion.
COMPLICATIONS OF CKD: mineral bone disorder
Abnormalities in calcium, phosphorous, PTH, Fibroblast Growth Factor 23 and Vitamin D metabolism.
Bone turnover and mineralization affected
Extraskeletal calcification
- **Reduced calcium absorption and vitamin D activity - due to Decreased renal production of 1 alpha hydroxylase - due to phosphate retention due to CKD
- -> leading to increase parathyroid hormone due to low calcium
COMPLICATIONS OF CKD: Cardiovascular Disease
Life expectancy is severely reduced in CKD – owing to a 16-fold increased incidence of cardiovascular disease.
Especially MI and Heart Failure.
Likely related to HTN, a frequent complication of CKD, and coronary artery calcification.
Pericarditis can also occur in severe uraemia.
Complications of CKD – Volume Overload
reduced perfusion –> RAAS –> vasoconstriciton and Na reabsorption –> Hypertension, p/p oedema
Complications of CKD – Patients can develop high K+ and acid base disturbances
increase K+ ====> ECG abnormalities
endogenous acid production increased, less output ====> Acid base disturbances
CKD Progression
CKD tends to progress to End Stage Kidney disease, although the rate of progression depends on underlying pathology.
Hypertension and Heavy Proteinuria are bad prognostic indicators.
CKD – What can we do about it?
Control HBP - below 140/90. if diabetic, aim <130/80
RAAS antagonists helpful eg Ramipril
Be careful in the elderly or those with neuropathy.
Set patient specific targets.
Need to manage cardiovascular risk.
Need to consider statins to lower cholesterol (i.e. correct abnormal lipid profiles)
Good glycaemic control - target HbA1c of 53mmol/mol
Salt intake reduced to < 2g per day, unless contraindicated.
Lifestyle changes – dietary advice, physical activity compatible with cardiovascular health and tolerance. Stop smoking.
CKD – Managing Complications
ANAEMIA
Investigate anaemia in CKD if Hb < 110g/litre or less; or develop symptoms
As due to erythropoietin (EPO) deficiency, can be treated with synthetic (recombinant) human EPO.
Need to investigate also for other causes of anaemia such as Iron Deficiency Anaemia.
Need to regularly monitor blood counts when using synthetic erythropoietin.
CKD – Managing Complications
Mineral Bone Disorder
Need to try and reduce phosphate levels – dietary restriction is seldom effective alone.
Can use Gut Phosphate binders to help absorb gut phosphate. Examples include calcium carbonate.
Can consider Vitamin D analogues such as alfacalcidol.
