Chronic Kidney Disease Guidelines
Step 1: Identify high
risk
Step 2: Case finding
Step 3: Evaluation and staging
Step 4: Determine cause
Step 5: Care objectives
Step 1: Identify
high-risk populations
Identify patients at risk of kidney disease based upon a directed medical and
surgical history including comorbidities (e.g. diabetes, cardiovascular
disease), as well as dietary, social, demographic, and cultural factors, a
review of symptoms, and physical examination.
High-risk populations include those:
with diabetes
with a diagnosis of hypertension +/- cardiovascular disease
with a family history of kidney disease
belonging to specific high-risk ethnic groups: First Nations and
Pacific Islanders.
Note: Age greater than 60 years is
associated with an increased risk of impaired kidney function. However, there
is insufficient evidence at this point to recommend screening all individuals
over 60 solely on the basis of age.
Step 2: Screen
high-risk populations
Screen high-risk populations every 1-2
years depending upon clinical circumstances (e.g. yearly for persons with
diabetes) using serum creatinine and random urine tests (also see Notes).
The estimated
Glomerular Filtration Rate (eGFR),
computed from the serum creatinine value, is the best laboratory marker
for kidney disease. Most laboratories in BC now automatically report eGFR when
a serum creatinine is ordered.
Persistent eGFR values < 60 mL/min
indicate substantial reduction in kidney function.
Urine test abnormalities, even with persistent
eGFR values =/<60 ml/min, indicate
abnormal kidney function, either as an isolated condition or as a symptom
of a systemic disease.
Random urine
tests for macroscopic and microscopic urinalysis and albumin/creatinine ratio
(ACR)
Significant abnormalities include the presence of persistent
white blood cells or red blood cells in the absence of infection or
instrumentation. The presence of any cellular casts is always pathological.
Elevation of ACR (> 2.0 mg/mmol males; > 2.8 mg/mmol
females) on 2 out of 3 serial tests, performed between 1 week and 2 months apart,
indicates micro-vascular disease +/- glomerular disease.
If test results are normal, repeat every
1-2 years and monitor blood pressure. If test results are abnormal, confirm the
abnormality, then evaluate as described in Step 3.
1. Persistent = present for > 3 months.
2. GFR estimates based on serum creatinine measurements may be
unreliable in patients with very large or small body habitus, those on specific
diets (very high or very low protein) and in patients receiving medications
that interfere with the measurement or excretion of creatinine (e.g.
trimethoprim and sulfamethoxazole, ciprofloxacin, fenofibrate).
3. 24-hour urine collections are not necessary in most cases.
4. ACR is also referred to as the test for microalbumin. Microalbuminuria
refers to urinary albumin excretion above the normal range, but below the
detection limit of tests for urinary total protein. Note that this guideline
uses the thresholds adopted by the Canadian Diabetes Association for the
detection of microalbuminuria. As methods improve and further data become
available, these cutoffs may be revised. Serial ACR tests can normally be
incorporated into the routine visit schedule.
5. Exercise, diet and/or hydration status may affect kidney
function estimates or the degree of albuminuria/proteinuria. If baseline tests
are abnormal or subsequent tests are significantly different from baseline,
confirmation by repeat testing is warranted.
Step 3: Evaluate patients
with abnormal screening test results in absence of other systemic
illness.
Kidney damage is
defined as pathologic abnormalities or markers of damage, including
abnormalities in blood or urine tests or imaging studies. Chronic kidney
disease is defined as either kidney damage or GFR < 60 mL/min for =/> 3
months.
If chronic kidney disease is present,
determine the stage of CKD based on eGFR,
urinalysis and ACR. The following staging system,
designed by the National Kidney
Foundation (US) with international input, is recommended to facilitate
assessment and management of kidney disease.
Consider both stage and results of urinalysis and ACR
testing
Stage |
Description |
eGFR |
Complications |
|
1 |
Kidney damage, N or ^ GFR |
>/= 90 |
None |
|
2 |
Mild v GFR |
60-89 |
some
^ PTH some
hypertension |
|
3 |
Moderate v GFR |
30-59 |
v Ca absorption v PO4 excretion Hyperparathyroid v Lipoprotein activity Malnutrition Onset
LVH Onset
anemia Hypertension |
|
4 |
Severe v GFR |
15-29 |
TG
rise ^
PO4 Malnutrition Met.
acidosis Onset
↑ K Hypertension |
|
5 |
Kidney Failure |
15 or Dialysis |
Azotemia Heart
failure and volume
overload Hypertension |
1. Urinalysis normal but ACR equivocal (2-20 M,
2.8-28 F)
·
Consider
kidney ultrasound
·
Annual
urinalysis and creatinine
·
Nephrology referral if urine protein
increasing or eGFR declining >10% annually.
2. Abnormal urinalysis or abnormal ACR (>20
M, >28 F)
·
Kidney
ultrasound to assess need for urgent referral
·
Nephrology referral
·
Urology
referral for hematuria even if US normal
1. Urinalysis normal or ACR equivocal (2-20 M,
2.8-28 F)
·
Consider
kidney ultrasound
·
Every
6 mo. urinalysis and creatinine
·
Nephrology referral if urine protein
increasing or eGFR declining >10% annually.
2. Abnormal urinalysis or abnormal ACR (>20
M, >28 F)
·
Kidney
ultrasound to assess need for urgent referral
·
Nephrology referral
·
Urology
referral for hematuria even if US normal
Regardless
of other results, refer to a nephrologist.
Regardless
of other results, urgent referral to a nephrologist.
Step 4: Determine the
cause of kidney disease
A primary cause of kidney disease should
be determined in all patients if possible; impaired kidney function is often
multifactorial. Kidney ultrasound is a useful examination
to identify polycystic kidney disease, cancer, stones, and obstruction, as well
as to screen for clinically significant renal artery stenosis. Furthermore,
kidney disease can be the first or most dramatic presentation of a severe systemic illness.
Even if a primary
cause seems obvious, the possibility of a serious underlying cause like
vasculitis, lupus or other conditions must be considered in patients with:
abnormal urinalysis (proteinuria, hematuria, cellular casts or combination
thereof)
rapid decline in kidney function (change in GFR > 10%/year)
repeated impairment of kidney function even in the absence of risk factors
constitutional symptoms suggesting systemic illness
sudden or severe onset of symptoms (e.g. edema unrelated to heart disease or
liver disease).
Refer to a specialist for further
evaluation if etiology cannot be determined.
Note: Occasionally a screening test will identify a serious
systemic disease or early stage of an acute illness. In those patients with
active urine sediments (RBC casts, cellular casts +/- protein), constitutional
symptoms or unexplained severity of kidney dysfunction, prompt consultation
with a specialist and/or re-evaluation of tests is indicated.
Step 5: Identify care
objectives (also see Practice Points)
Identify care objectives for all patients
with CKD In your practice. Depending on the
level of kidney function and complexity of therapy required, these care
objectives may be more or less difficult to achieve without help from a
specialized team of health care professionals, including a nephrologist. Treatment goals must therefore be
tailored to the individual.
Blood pressure:
Measure and record at diagnosis and at every visit thereafter. BP less
than130/80 Use of ACEI/ARB recommended in addition to other drugs
Kidney
function: Obtain regular measurements of serum
creatinine for estimates of GFR (at least q
6 mths) and after any change in
medications, medical interventions or clinical status.
Aim for stability of kidney function or measurements < 10% decline in GFR annually.
Urine
testing: ACR (microalbumin)
regularly (at least q 6 mths) Reduce abnormal values by 50% or more from
baseline Use of ACEI/ARBs recommended.
Cardiovascular
disease risk assessment and lipid
profiles: Calculate & record cardiovascular risk
and manage in accordance with relevant
guidelines. Check fasting lipids yearly once
target values achieved, more frequently in patients on lipid lowering
medication. Lipid targets: LDL < 2.5 Ratio (TC/HDL) < 4.0
Assessment
of conditions associated with CKD: Measure hematology profile, mineral
metabolism, and nutrition profiles at least yearly, more frequently with
advanced kidney disease. Hgb > 120 g/L Transferrin saturation > 20%
Calcium > 2.2 mmol/L Phosphorus < 1.4 mmol/L iPTH in normal range
Albumin in normal range
Diabetes: Measure A1C every 3
months. A1C: </= 7.0% (0.07)
Weight
and nutrition: Record weight & BMI on each visit for
comparison. Maintenance of adequate nutrition
and BMI near ideal (18.5-24.9)
Smoking: Encourage patient to stop; enquire at every
visit; Aim for complete cessation
Hepatitis
B screening: Identify seronegative patients; offer
vaccination. Prevention of Hepatitis B (Seroconversion rate higher if immunized
early)
Influenza vaccine: Immunize annually.
Pneumococcal vaccine: Immunize every 10 years.
Limit
exposure to nephrotoxins: Reduce risk of acute or chronic
deterioration of kidney function. Avoidance of aminoglycosides, NSAIDs, COX-2
inhibitors, intra-venous or intra-arterial radiocontrast
studies.
Psychosocial
health: Identify depression and grief reaction often
associated with chronic disease. Identify and address psychosocial problems
that affect the illness.
● Reduction of proteinuria can be facilitated by the use of
ACEI/ARBs. This has been shown to reduce the rate of progression of chronic
renal insufficiency in hypertensive patients with diabetes or chronic
glomerulonephritis.
● In patients
with severe kidney disease (GFR < 15ml/min), weight loss may indicate a
catabolic state and possibly the need for dialysis.
When setting goals with your patient,
consider the following:
1.
Exercise, diet
and/or hydration status may affect kidney function estimates or the degree of
albuminuria/proteinuria. If baseline tests are abnormal or subsequent tests are
significantly different from baseline, confirmation by repeat testing is
warranted
2.
Rigorous control of blood pressure has been
shown to reduce the risk of complications and mortality rates. In particular,
the inhibition of the renin angiotensin system with ACE inhibitors or ARBs has
been shown to be very effective. Target
BP is < 130/80 mmHg. Most patients
will need 3 or more medications. Diuretics and salt restriction are very
useful, and if needed, consider furosemide BID dosing when eGFR < 30
ml/min/1.73m2.
3.
Every adult with kidney disease is
at high to very high risk of cardiovascular disease (CV risk >> ESRD risk).
Use risk factor modification.
4.
Nephrotoxic medication (e.g. NSAIDs,
COX-2 inhibitors, aminoglycosides) should be avoided or used with caution in
patients with even mild kidney impairment (eGFR 60-90 ml/min), and kidney
function should be monitored if they are used.
5.
Intra-venous or intra-arterial
radiocontrast use poses a high risk of acute kidney failure in CKD patients
with Stage 4 or 5 CKD and a moderate risk in patients with Stage 3 disease. If imaging is required, alternate imaging techniques, including
MRI angiography, should be considered for these patients. If no alternative
exists and the procedure is medically necessary, the patient should give
written informed consent and protection with IV hydration and N-acetyl cysteine
should be used according to a published protocol.
6.
Review medication list, identify
those excreted by the kidneys and dose adjust as appropriate. Three examples include metformin,
digoxin and lithium.
7.
Referral to a nephrologist is
recommended for:
a.
acute kidney failure
b.
eGFR < 30 ml/min/1.73m2. (CKD stage 4 and 5) with progressive decline of
eGFR
c.
urine protein/creatinine ratio
(PCR) > 100 mg/mmol (~900 mg/24 hours) or urine albumin to creatinine ratio
(ACR) > 60 mg/mmol (~500 mg/24 hr) ie. inability to achieve treatment targets
8.
Preparation for kidney replacement
treatment requires a minimum of 12 months. Referral for consideration of kidney
replacement should take this into account.
9.
Many patients with CKD also have diabetes and/or
heart disease. Explaining the linkage between these conditions and how treating
one condition benefits others may lessen the psychological impact of several
separate diagnoses.
10.
Target urine protein/creatinine ratio (mg/mmol) is < 60
(< ~ 500 mg/day) or target urine albumin/creatinine ratio (mg/mmol) is < 40. ACEI and/or
ARB are first line therapies in patients with albuminuria or proteinuria.
11. Consider reversible factors, such as medications, intercurrent illness, volume
depletion, or obstruction. An abdominal ultrasound may be indicated when eGFR <60 ml/min/1.73m2.
1. Guidelines and Protocols Advisory Committee. Identification, evaluation and eanagement of
patients with chronic kidney disease.
BC Health Services 2004.
Available from: www.healthservices.gov.bc.ca/msp/protoguides/gps/ckd.pdf
2. Position Paper of the Canadian Society of Nephrology. Care and referral of adult patients with
reduced kidney function. 2006. Available from: www.csnscn.ca
3. Craven NH. Management of
chronic kidney disease in the primary care setting. BC Medical Journal 2005; 47(6): 296-299.