Renal Disease
Chronic Kidney Disease
GP Management
Ross Bills
Prevalence
1.7 million Australians with Stage three chronic
kidney disease
1 in 7 Australians has chronic kidney disease
Often asymptomatic, 80-90% of cases
unrecognised and untreated
10-20 fold increase in risk of death due to
cardiovascular events
1 nephrologist per 95,000 adult Australians
Diagnostic criteria
Chronic kidney disease (CKD) is defined as:
• A glomerular filtration rate (GFR) less than 60
mL/min/1.73m2 that is present for 3 or more months, with
or without, evidence of kidney damage
OR
• Evidence of kidney damage (with or without decreased
GFR) that is present for
> 3 months, as evidenced by
any of the following
• Microalbuminuria
• Proteinuria
• glomerular haematuria
• pathologic abnormalities (e.g. abnormal renal biopsy)
• anatomical abnormalities (e.g. scarring seen on
imaging or polycystic kidneys).
GP Role
early detection of CKD
instituting therapies which will slow or
prevent progression to kidney failure
assessing and modifying cardiovascular
risk factors
avoiding nephrotoxic drugs
eGFR
The MDRD (abbreviated) equation for use
with SI units is:
GFR = 186 x {[SCr (umol/L)/88.4]-1.154} x
(age)-0.203 x (0.742 if female)
Pathologies
• Easiest to think of
– Pre-renal
• Hypertension
• Renal artery stenosis
• Phaeochromocytoma
• Multiple organ failure/shock
– Renal
• Glomerulopathies: acute and chronic, infective,
autoimmune, protein deposition (amyloidosis), chemical
(lead), drug related
• Diabetes nephropathy
• Mass - tumour (adenocarcinoma commonest adults,
nephroblastoma children), polycystic disease
– Post-renal
• Calculi and other obstructive (analgesic nephropathy)
• Strictures ureter intrinsic and extrinsic
Risk Factors
Smoking
Diabetes
Hypertension
Age > 50 years
Family History of Kidney Disease
ATSI Patients
The Kidney Screen
Simple screen at presentation.
If risk factors present:
• Check BP
• Dipstick for protein
• Creatinine level for eGFR
If eGFR > 60, normal BP, No proteinuria, low
risk. Review opportunistically.
Caution if other evidence of renal disease -
haematuria, casts etc.
eGFR
The new measure of renal function, using
prediction equations based on age, sex and
creatinine clearance
Abbreviated MDRD Formula
• GFR = 186 × (SCR + 88.4)-1.154 × AGE-0.203
• Female: multiply result by 0.742)
• When used in Afro-Americans the result should be multiplied
by 1.21
eGFR 2
Clinical situations where eGFR results may be unreliable
and/or misleading:
• Acute changes in kidney function (eg. acute kidney failure)
• Dialysis-dependent patients
• Exceptional dietary intake (eg. vegetarian diet, high protein diet,
creatine supplements)
• Extremes of body size
• Diseases of skeletal muscle, paraplegia, those with high muscle mass
and amputees
• Children under the age of 18 years
• Severe liver disease present
• eGFR values above 60 mL/min/1.73m2
eGFR 3
eGFR has not been validated or shown to have acceptable
accuracy in:
• Aboriginal and Torres Strait Islander peoples
• Asian populations (including Japanese, Chinese and Vietnamese)
• Maori and Pacific Islander peoples
• Calculations for drug dosing
In these clinical situations listed, an alternative method of
estimating kidney function should be performed.
Presentations
Stage 1 - Kidney damage, no loss of function
Stage 2 - Kidney damage with mild loss of
function
• There may be no clinical diagnostic features other than mild
impairment of Creatinine Clearance/eGFR (eGFR >60)
• Address co-morbidity:
• BP
• Lipids
• Diabetes
• Smoking
• Weight
• Exercise
Signs/Symptoms Stage I - II
Bugger all
Complications Stage I - II
Usually just hypertension if anything
Presentations 2
Stage 3 - moderate loss kidney function
eGFR 30-59
• Look at modifiable risk factors
• Monitor eGFR (three monthly
• Consider referral to nephrologist
Stage III Clinical Findings
Nil or
nocturia
mild malaise
anorexia
Stage III Complications
• Hypertension
• Hyperparathyroidism
• Renal Osteodystrophy
• Anaemia
• Sleep Apnoea
• Restless legs
• CVD
• Malnutrition
Management Stage III
Diagnosis
Cardiac and kidney risk factor
modification
Treat complications
Modifiable Risk Factors
• Avoid nephrotoxic drugs
• Consider ACE Medication (inhibitors/blockers) -
(antiproteinuric effect)
• Address co-morbidities:
• BP
• Lipids
• Diabetes
• Smoking
• Weight
• Exercise
• Correct:
• Anaemia
• Acidosis
• Hyperparathyroidism
• Ensure appropriate drug doses for renal function
Non-modifiable Risk Factors
Can’t change:
• Age > 50 years
• Family History of renal disease
• ATSI heritage
Presentations 3
Stage 4 - severe decrease renal function
eGFR 15-29
Needs referral to nephrologist. Considering
dialysis, shunt for access, education and
transplantation
Stage IV Clinical Findings
Nil or nocturia,
malaise
anorexia
nausea
pruritis
restless legs
dyspnoea
Stage IV Complications
• Hypertension
• Hyperparathyroidism
• Renal Osteodystrophy
• Anaemia
• Sleep Apnoea
• CVD
• Malnutrition
• Hyperphosphataemia
• Acidosis
• Hyperkalaemia
Management Stage IV
Diagnosis
Cardiac and kidney risk factor
modification
Treat complications
Dialysis education
Dialysis access surgery
Referral to Nephrologist
Indications for Referral to a Nephrologist
• eGFR 15% in eGFR over 3 months
irrespective of baseline level)
• Proteinuria >1g/24 hrs
• Glomerular haematuria
• Kidney disease and hypertension that proves difficult to control
• Diabetes and eGFR 30 mins/day physical activity
• BMI 1g/day
• ACEI and/or ARB first-line
• lifestyle modification
Proteinuria
> 50% reduction of baseline value
• ACEI and/or ARB first-line
Cholesterol
Total Cholesterol 6.0 mml/L
• Dietary advice
• Diuretics
• Resonium???
• Cease ACEI/ARB if K+ persistently > 6.0
mmol/L
Hyperparathyroidism
PO4 1.6 mmol/L
PTH 2-5 x upper limit of normal
Calcitriol
Phosphate binders (calcium carbonate,
aluminium hydroxide, magnesium
trisilicate, sevelamer)
Cinacalcet
Malnutrition
Albumen < 35 g/L
Dietary advice
Sleep apnoea
Prevent apnoeac episodes
Manage condition:
• Weight reduction
• Avoid CNS depressants
• CPAP therapy (if obstructive pattern
Restless legs
Correct iron deficiency
Dopaminergic agents
Herbal options: Crampeze,
Exercise/stretches
Drugs to reduce or cease
• Acetazolamide
• Acyclovir
• Colchicine
• Digoxin
• Gabapentin
• Lithium
• metformin (significantly increased risk of lactic
acidosis when GFR < 50 mL/min/1.73m2)
• Sotalol
• sulphonylureas.
Drugs affecting renal function in
CKD
• NSAIDs and COX-2 inhibitors
• ACE inhibitors and angiotensin II receptor
antagonists
• beware, especially, the 'triple whammy' of
NSAID/COX-2 inhibitor, ACE inhibitor and
diuretic
• radiographic contrast agents
• Aminoglycosides
• lithium.
Renal osteodystrophy
• Renal osteodystrophy is multifactorial. The aetiology includes:
• Reduced production of the active form of vitamin D by the diseased
kidneys. A drop in vitamin D reduces the intestinal absorption of
calcium and causes a fall in the blood level of calcium.
• If calcium levels in the blood become too low, parathyroid hormone
(PTH) production is increased. PTH tries to keep the calcium level in
the blood normal by:
– increasing calcium resorption from bones
– increasing production of vitamin D by the kidney in an attempt to increase
calcium absorption from the intestine
– increasing resorption of calcium by the kidneys to reduce renal losses.
– Vitamin D and PTH usually work together to maintain calcium homeostasis.
However, in CKD, the kidneys have a reduced ability to produce the active
form of vitamin D and the hypocalcaemia that develops cannot be corrected.
This causes PTH levels to rise still further. Because the intestinal absorption
of calcium is impaired, the net result is resorption of calcium from the bones.