Chronic Kidney Disease Dr Fenella Mayle Fordbridge Medical Centre 26.11.12
CKD • Chronic renal failure is the progressive loss of nephrons resulting in permanent compromise of renal function.
Identification of risk groups • Testing for CKD should be undertaken in the following groups: • Diabetes • Hypertension • Cardiovascular disease (IHD, chronic heart failure, peripheral vascular disease, cerebral vascular disease) • Structural renal tract disease, renal calculi, prostatic hypertrophy • Multisystem diseases with potential kidney involvement, eg, SLE • FHx of CKD 5 disease or hereditary kidney disease • Opportunistic detection of haematuria or proteinuria • Monitor eGFR in pt’s prescribed known nephrotoxic drugs such as lithium. • Pt’s should have annual eGFR testing if on long-term NSAIDs
CKD testing • Clinicians should use urine albumin:creatinine ratio (ACR) in preference to protein:creatinine ration (PCR) in order to detect proteinuria as ACR has greater sensitivity compared to PCR for low levels of proteinuria • All patients with diabetes, and patients without diabetes with a GFR less than 60 ml/min/1.73 m^2, should have their urinary albumin/protein excretion quantified. The first abnormal result should be confirmed on an early morning sample (if not previously obtained) • Urine dipstick should be completed for assessment of renal disease, especially in those patients with risk factors such as hypertension, DM. • Proteinuria should ideally be identified using albumin:creatinine ratio (ACR). Protein should not be assessed on a standard urine dipstick reagant strip as this method is not accurate • Haematuria can be assessed on simple dipstick. Any result of 1+ or above should be considered postive. • Renal USS is not routinely required. It may be indicated in the case of • Progressive CKD • Visible or persistent haematuria • Symptoms of urinary tract obstruction • Family Hx of polycystic kidney disease in a patient over 20yrs old • CKD stage 4 or 5
Interpretation of proteinuria and haematuria Non-diabetic patients • ACR <30mg/mmol = Normal • ACR 30-69 = Significant proteinuria present • ACR>70 = Heavy proteinuria present • If ACR 30-69mg/mmol, confirm with repeat test using an early morning urine sample • If ACR>70 no repeat is necessary Diabetic patients • ACR <2.5mg/mmol in men, <3.5 in women = normal • ACR >2.5 in men, >3.5 in women = microalbuminuria is present Haematuria • If present and no proteinuria, confirm on 2 out of 3 dipsticks over 4 weeks • If persistent, see further management guidelines • If present with proteinuria, patient will need specialist review
Practical tip • These urinary protein figures, expressed as ACR can be difficult to put into context. They are comparable to 24-hour urinary protein excretion. • Roughly speaking • ACR of 30mg/mmol = 0.5g protein/day on a 24-hour urine • ACR of 70mg/mmol = 1g protein/day on a 24-hour urine
NICE advise to take the following steps to identify progressive CKD • Obtain a minimum of three GFR estimations over a period of not less than 90 days. • Patients with a new finding of reduced eGFR (<60), repeat the eGFR within 2 weeks to exclude causes of acute deterioration of GFR - for example, acute kidney injury or initiation of ACE inhibitor/ARB therapy • define progression as a decline in eGFR of more than 5 ml/min/1.73 m^2 within 1 year, or more than 10 ml/min/1.73 m^2 within 5 years • Risk factors for progression include cardiovascular disease, proteinuria, hypertension, smoking, black or Asian ethnicity, chronic use of NSAIDs, urine outflow obstruction • focus particularly on those in whom a decline of GFR continuing at the observed rate would lead to the need for renal replacement therapy within their lifetime by extrapolating the current rate of decline
Staging CKD • Stage 1: Normal GFR; GFR >90 mL/min/1.73 m2 with other evidence of chronic kidney damage • Stage 2: Mild impairment; GFR 60-89 mL/min/1.73 m2 with other evidence of chronic kidney damage • Stage 3: Moderate impairment; GFR 30-59 mL/min/1.73 m2 • Stage 3 CKD should be split into two subcategories: • GFR 45-59 ml/min/1.73 m2 (stage 3A) • GFR 30-44 ml/min/1.73 m2 (stage 3B) • Stage 4: Severe impairment: GFR 15-29 mL/min/1.73 m2 • Stage 5: Established renal failure (ERF): GFR < 15 mL/min/1.73 m2 or on dialysis (the term established renal failure is used instead of end-stage renal disease or end-stage renal failure, as this is the term used in the National Service Framework for Renal Services)
CKD staging • other evidence of chronic kidney damage may be one of the following: • persistent microalbuminuria • persistent proteinuria • persistent haematuria (after exclusion of other causes, e.g. urological disease) • structural abnormalities of the kidneys demonstrated on ultrasound scanning or other radiological tests, e.g. polycystic kidney disease, reflux nephropathy • biopsy-proven chronic glomerulonephritis (most of these patients will have microalbumuria or proteinuria, and/or haematuria) • patients found to have a GFR of 60-89 mL/min/1.73 m2 without one of these markers should not be considered to have CKD and should not be subjected to further investigation unless there are additional reasons
Does stage 3 CKD matter? • 5% of the adult population is estimated to have stage 3 CKD and they make up vast majority of patients on practice CKD registers. • In a typical 10,000 patient practice, every year: • 144 new pt’s with stage 3 CKD will be identified • 3 new pt’s with stage 4 will be detected • Only 1 new pt with stage 5 CKD will be detected • The BJGP review found: • The relative risk of mortality (all-cause or CVD) was higher in stage 3 compared with no CKD • The increased risk was greater in stage 3B cf to 3A • Mortality rate for stage 3B was 4.8 per 100 years compared with 1.1 for stage 3A • Over 80% of pt’s with CKD stage 3 did not show worsening of stage over 5 years • BJGP concluded that a diagnosis of stage 3 CKD does matter as it provides an opportunity to assess CVD risk and optimise care for those at highest risk.
How should you manage a patient with newly identified low eGFR? • Do not view reading in isolation • Review previous results and assess rate of deterioration • Check Hx and review medications – any nephrotoxic drugs • Check BP and conduct clinical assessment – (eg, is there a palpable bladder?) • Check urine – dipstick for blood and send for ACR • Repeat eGFR within 2 weeks and rv with urine results. If all appears stable, take a third eGFR within 3 months • Stage the CKD – Read code and then investigate/refer/manage as appropriate
Management of patients with chronic kidney disease (CKD) in primary care • regular measurements of kidney function using serum creatinine concentration and estimated GFR, depending on the severity of kidney impairment (annual in stage 1 and 2 and stage 3 if known to be stable, 6-monthly for newly diagnosed or progressive stage 3) • advice on smoking cessation • advice on weight loss if obese • encouragement to take regular aerobic exercise • advice to limit alcohol intake to no more than 3 units/day (men) or 2 units/day (women) • consideration of aspirin treatment for all patients with an estimated 10 year risk of cardiovascular disease of > 20%, so long as blood pressure is < 150/90 mm Hg • meticulous control of hypertension if present • lipid lowering
When should patient be referred? • A patient with CKD should normally be referred to a renal specialist in the case of: • Stage 4 or 5 disease • High levels of proteinuria (ACR>70mg/mmol) • Proteinuria (ACR>30mg/mmol) and haematuria • Rapidly declining eGFR (>5ml/min/1.73m in one year, >10 in 5 years) • Poorly controlled hypertension, despite at least 4 drugs • Suspected renal artery stenosis or rare/genetic cause for CKD
Hypertension in CKD • ACEi and ARbs have a renal protective effect beyond simple BP control • BP targets: usually <140/90. If DM or high levels of proteinuria (ACR>70mg/mmol), target is <130/80 • Offer ACEi first-line in : • Patients with DM and microalbuninuria (ACR>2.5 in men, >3.5 in women) • Patients with high levels of proteinuria (ACR>70) irrespective of BP control • Patients with hypertension and significant proteinuria (ACR>30)
ACEi/ARBs • Use the maximum tolerated dose • Check eGFR and potassium after 1-2 weeks • If eGFR declines by less than 25% continue and monitor • If eGFR declines by more than 25% exclude acute causes and stop ACEi/ARB • If baseline potassium is >5, don’t start ACEi/ARB • If potassium increases to 6 stop ACEi/ARB • NB. If patients with ACR <30mg/mmol and no DM – treat BP as per normal hypertension guidelines
Should CKD pt’s be treated with statins? • No absolute requirement for CKD pt’s to receive statins, however, as in any other pt they do form part of cardiovascular risk management. • Use of statins in primary prevention should be the same as in pt’s without CKD – offer if the CVD risk over 10 years is greater than 20%. QRISK2 risk calculator adjusts for CKD when calculating a pt’s risk score. • Statins should be used in 2y prevention irrespective of baseline lipid levels – aiming for target total chol <4 and LDL <2mmol/L
Other complications: • Anaemia • If not already measured, test in CKD stage 3B, 4 and 5. Treat following NICE guidelines for anaemia • Bones • Measure PTH, calcium and phosphate only in stage 4 and 5 • Offer bisphosphonate if indicated to prevent osteoporosis in stage 1-3B. They are not recommended in stage 4 and 5.