Australian Doctor 8th Nov Issue | Page 30

8 NOVEMBER 2024 ausdoc . com . au

Box 2 . Additional investigations to consider

• Determine the presence and severity of high blood pressure with repeated monitoring . — In patients with chronic kidney disease ( CKD ), a better understanding of the blood pressure can be achieved with the use of ambulatory blood pressure monitoring , or home blood pressure monitoring as compared with standard office blood pressure . 19

— CKD is often associated with ‘ masked hypertension ’ and high nighttime blood pressure readings without the nocturnal dipping of blood pressure that characterises healthy vascular function .

• This may not be detected on standard office blood pressure measurements . As a result , ambulatory blood pressure is considered to be a stronger predictor of kidney function decline and target organ damage than office blood pressure in CKD . 19

• Obtain a family history of any CKD .

• Take a thorough history of previous exposure to potential nephrotoxins ; this includes a full medication history and exposure to chemotherapeutic agents , immune checkpoint inhibitors , PPIs , illicit drugs , herbal remedies , heavy metals , and mining and agricultural chemicals .

• Ask about the potential risks of exposure to HIV or hepatitis B and C , such as a history of drug use , or risks of an STI , as viral infection may precipitate kidney damage in some individuals .

• Undertake screening for unrecognised diabetes in people with CKD , by ordering a fasting blood glucose level and measuring the HbA1c . At least one in four patients with newly diagnosed diabetes already have CKD . 20

• Order urine microscopy to identify potential signs of glomerulonephritis ( eg , haematuria , urinary casts , heavy proteinuria ).

• In non-diabetic individuals , retinal examination can also provide evidence of chronic high blood pressure , with arteriovenous nicking , the development of microaneurysms and haemorrhages consistent with ‘ hypertensive retinopathy ’.

• Symptoms and signs of heart failure are often associated with CKD , as the same process ( es ) that damage the kidney also damage the heart . 21

• Enlarged kidneys that are palpable on examination may suggest polycystic kidney disease .

• Some doctors will also request a kidney ultrasound regardless , to exclude polycystic kidney disease , reflux nephropathy , urinary tract obstruction or other structural abnormalities . The kidneys of people with CKD are usually small with increased echogenicity ( eg , kidneys are more echogenic than the liver ). This provides evidence of chronic kidney pathology , although normal renal ultrasound does not exclude it .

• Renovascular disease may also present with CKD and high blood pressure :

— In patients with atherosclerosis in other vascular beds ( such as in the legs , coronaries or carotids ), or those with high-risk clinical presentations ( flash pulmonary oedema , refractory hypertension , or rapid loss of kidney function ) also consider investigations for renal artery stenosis . 19 — An abdominal bruit or abnormal distal pulses may also be suggestive . — Vascular duplex ultrasound of the renal arteries can be requested as part of the initial ultrasound evaluation and then angiography undertaken as required .

• In older adults with declining kidney function and proteinuria , urine and protein electrophoresis and a serum free light chain assay may be appropriate to exclude multiple myeloma .

• Although not currently available in Australia , in the future , genetic testing of people first presenting with CKD will also become standard . In particular in African ancestry , it is now clear that certain apolipoprotein L1 gene variants are associated with the majority of cases presenting with non-diabetic CKD and many of those labelled as having diabetic nephropathy .

Kidney Function Stage

1 ≥90 2 3a

3b 4 5

Offer a Kidney Health Check to people with

• Diabetes

• Hypertension

•

•

Established CVD Family history of kidney failure

• Obesity ( BMI ≥30 )

• Current or past smoker / vaper

• History of AKI

• First Nations Australians aged ≥18 years

• All Australians aged ≥60 years

Repeat uACR within 3 months . If uACR normal , complete a third test ( preferably first morning void )

Repeat eGFR within 7 days

Repeat eGFR within 3 months

Stage CKD with staging table , using eGFR and uACR test results

GFR

Normal ( mL / min / 1.73m 2 ) ( A1 ) uACR < 3.0 mg / mmol

60-89 45-59 30-44 15-29 < 15 or on dialysis uACR ≥3 mg / mmol eGFR < 60 mL / min / 1.73m 2 No

Yes

If minimum of two uACRs ≥3 mg / mmol over 3 months

Not CKD unless haematuria , structural or pathological abnormalities present and / or

If minimum of two eGFRs < 60 mL / min / 1.73m 2 over 3 months

Albuminuria Stage

Microalbuminuria ( A2 ) uACR 3.0-30 mg / mmol

Undertake investigations to determine underlying diagnosis

If ≥20 % reduction in eGFR , possible AKI . Discuss with nephrologist

Macroalbuminuria ( A3 ) uACR > 30 mg / mmol

Fully specify CKD diagnosis , e . g CKD stage 2 with microalbuminuria ( A2 ) in the presence of type 2 diabetes

Refer to the colour-coded clinical action plans for CKD management strategies : Yellow clinical action plan Orange clinical action plan Red clinical action plan

Figure 6 . Algorithm for initial detection and diagnosis of chronic kidney disease ( CKD ). AKI = acute kidney injury ; uACR = urinary albumin to creatinine ratio .

Yes

Hypertensive CKD

Repeat Kidney Health Check in 1-2 years ( annually in First Nations Australians aged ≥18 , people with diabetes or hypertension )

Chronic Kidney Disease Management in Primary Care ( 5th edition ). Kidney Health Australia , Melbourne , 2024 17

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It is generally recommended that blood pressure lowering in patients with CKD and high blood pressure should at least include agents that block the RAAS , that is , an ACEI or ARB , but not both , where tolerated . 6 This recommendation is based on evidence that RAAS inhibitors slow the rate of decline of kidney function and reduce the incidence of ESKD in patients with established CKD . 6 In studies undertaken in patients with CKD at a high risk of progression to ESKD ( eg , patients with proteinuria ), inhibition of the RAAS appears to have additional benefits to slow kidney function decline beyond blood pressure lowering .

In patients with CKD without proteinuria , the benefits of RAAS inhibition beyond blood pressure lowering remain controversial , although their efficacy and tolerability as blood pressure lowering agents and action to reduce heart failure hospitalisation sees them used in preference in most patients with CKD . However , note that the incidence of AKI , hypotension and hyperkalaemia are substantially increased when initiating or increasing doses of RAAS inhibitors in patients with CKD . A cautious approach with close monitoring is recommended ( see figure 9 ).

A novel potassium binder such as patiromer will effectively normalise hyperkalaemia ( potassium 6.0mmol / L or greater ) in patients with CKD , and enable adequate dosing with RAAS inhibitors . This binder is PBS funded and can be used by GPs .

Combination therapy to control high blood pressure in CKD will also often require a long-acting dihydropyridine calcium-channel blocker , a thiazide-like diuretic ( eg , chlorthalidone ), or both . This is ideally delivered as a fixed-dose combination with RAAS inhibition to enhance treatment adherence . Doses of each should be titrated according to achieved and target blood pressure , up to the maximum tolerated . Beta blockers may also be considered in patients with CKD and heart failure with reduced ejection fraction , coronary artery disease or arrythmia , because of their additional cardioprotective effects .

As those with CKD often experience a non-dipping pattern of high blood pressure , it has been suggested that evening dosing with

Assess and manage residual risks

First-line

Foundation

antihypertensive agents could be beneficial . This is known as ‘ chronotherapy ’. In a small study of patients with CKD , evening dosing was associated with better blood pressure control and lower incidence of major cardiovascular events than those

Diet and lifestyle optimisation Adherence plus education plus monitoring Avoid nephrotoxins and volume depletion Appropriate and timely referral

Figure 7 . The management of chronic kidney disease ( CKD ) in patients with hypertension . ACR = albumin to creatinine ratio ; BP = blood pressure ; RAASi = renin angiotensin aldosterone system inhibitor .

who took all medications in the

27 , 28 morning .

In some patients with CKD , their blood pressure remains uncontrolled despite adherence to maximally tolerated doses of an RAAS blocker , a calcium-channel blocker and a diuretic .

This is the definition of ‘ resistant high blood pressure ’. 9 In such patients , the use of mineralocorticoid receptor antagonists ( MRAs ) is often recommended ( as the fourth-line agent ), based on superior efficacy in trials . 9 , 29 The increased risk of AKI