Diabetic nephropathy is an important complication of diabetes, and it is the main cause of end-stage kidney disease in New Zealand1. Māori and Pasifika are at higher risk of developing renal impairment because of diabetes. End-stage kidney disease due to diabetes is more common among these groups than Pakeha2.
Microalbuminuria is an early sign of diabetic kidney disease. It is associated with increased cardiovascular risk, as well as increased risk of CKD progression and mortality. However, regression of microalbuminuria can be achieved through better glycaemic control, better hypertension control and use of medications such as ACE inhibitors/ARB and SGLT-2 inhibitors. It is also easier to reverse microalbuminuria of a shorter duration. Hence, it is important to identify and treat patients assertively.
This MedCase discusses key risk factors, identifies the appropriate patients for screening, and discusses helpful assessment tools and evidence-based management strategies for slowing the progression of renal impairment.
Leilani is a 52-year-old Samoan female. She was diagnosed with Type 2 diabetes 7 years ago and is managed on metformin.
Over the weekend, she visited her best friend, who has started dialysis for renal failure.
Her friend was told she has diabetic kidney disease, and now Leilani is concerned her diabetes will also lead to renal failure.
She wants to know if her kidneys are at risk.
Identifying high risk patients
Early identification of high-risk patients enables accurate screening and timely intervention. Well-known risk factors for CKD, especially in the context of diabetes, include:
- hypertension
- overweight/obesity
- presence of proteinuria in urine ACR testing
- age over 60 years
- family history of chronic kidney disease
- smoking history
- use of nephrotoxic medications e.g. NSAIDs
- ethnicity – Māori, Pasifika, Indo-Asians.
You undertake a full review of Leilani’s medical records, results and examine her today.
Medical background:
- Hypertension diagnosed 3 years ago, on candesartan
- Diabetes diagnosed 7 years ago, on metformin
- Dyslipidaemia diagnosed 12 years ago, on statin
- Never smoked, 2 alcoholic drinks per month on social occasions
- There is a family history of type 2 diabetes, but she is not aware of any other conditions
Current medications:
- Metformin 1 g BD
- Candesartan 8 mg OD
- Atorvastatin 20 mg OD
Recent blood results from 3 months ago:
- HBA1c 63 mmol/mol
- Lipids: total cholesterol 4.2 mmol/L, LDL 3.2 mmol/L
- EGFR 84 ml/min/1.73m2
- Sodium 141 mmol/L
- Potassium 3.9 mmol/L
- No urine ACR on file
Examination findings today:
- BP: 128/76 mmHg
- Weight: 102 kg (up from 93 kg last year)
- BMI: 32
- Heart and lung exam normal
- No peripheral oedema
Based on these findings, you determine that Leilani is at increased risk of diabetic kidney disease.
Screening
High-risk patients should be specifically screened for renal impairment by checking serum creatinine and glomerular filtration rate (eGFR), along with a urine albumin: creatinine ratio (ideally checked first thing in the morning). These should be done at the time of diagnosis of diabetes, and at least yearly, or more often if abnormal.
Regular blood pressure monitoring is also essential, noting that the target blood pressure for diabetics is lower than for non-diabetics (130/80 mmHg) – the main exception being the very old or frail, who may be prone to postural hypotension and falls.
Simple online risk calculators e.g. The Kidney Failure Risk Equation can be used to calculate a person’s risk of progressive renal impairment.
You ask Leilani to have repeat lab work, including a urine ACR, repeat EGFR and HBA1c.
On the follow-up consult, you discuss her results:
- Urine ACR: 12 ml/mmol (confirmed on repeat testing)
- HBA1c: 64 mmol/mol
- EGFR: 83 ml/min/1.73m2
The results confirm that Leilani has micro-albuminuria and mild renal impairment. Thankfully, her risk of progressing to dialysis in the next 5 years is very low. She is motivated to make changes to her lifestyle and start new medications if needed.
Management
Addressing the risk factors for renal impairment will help to maintain kidney function and reverse early changes. These include:
- tighter control of diabetes
- lowering blood pressure
- management of dyslipidaemia
- smoking cessation
- weight loss through diet and exercise.
Medical management is required when EGFR > 60 and ACR > 3:
- Treatment with an ACE-I/ARB is indicated regardless of blood pressure (although there is a move towards ARBs over ACE-I due to a better side effect profile).
- Considering a SGLT 2 inhibitor, e.g. empagliflozin.
- Avoidance of nephrotic medications, especially NSAIDs. Particular care should be paid to the triple whammy scenario3.
You have a long conversation with Leilani about her rising HbA1c and weight. She admits that she has not been as diligent with her exercise and diet over the last year due to various family and work commitments.
However, she is motivated to make lifestyle changes to protect her kidneys. She plans to join her local exercise group and attend at least three times a week, and will discuss diet changes with her family at home. She sets a weight loss goal of 5kg in the next 6 months.
You deem that Leilani is eligible for funded empagliflozin based on special authority criteria. You advise her that it will help with her diabetic control and, therefore, help to protect her kidneys.
You discuss common side effects of the medication including polyuria, increased risk of UTI, and rash.
You start Leilani on 10 mg of empagliflozin OD. You agree to continue her metformin.
Leilani’s LDL is slightly raised. You discuss that she may benefit from a higher dose of statin in the future, but decide to hold steady for now.
You commend Leilani on her good blood pressure control. No changes are necessary with her candesartan.
Monitoring
Regular review e.g. 3 to 6 months is recommended with early/mild renal impairment, becoming more frequent if renal disease progresses. Attention should be paid to assessing cardiovascular risk factors including blood pressure, weight and smoking status.
The following labs should be checked at least annually, with more frequent checks as disease progresses or there are medication changes:
- Sodium, potassium, EGFR
- Urine ACR
- Full blood count
- HBA1c
- Lipids.
At the 3-month follow-up visit, you discover that Leilani has been exercising regularly and has made positive diet changes. She is tolerating the empagliflozin well.
Findings today:
- HBA1c: 56 mmol/mol
- EGFR: 62 ml/min/1.73m2
- Urine ACR: 1.8 ml/mmol
- Lipids: total cholesterol 4.3 mmol/L, LDL 3.1 mmol/L
- Blood pressure 124/72 mmHg
- Weight 98 kg
- BMI 30
Leilani agrees with your recommendation to increase the atorvastatin to 40 mg to improve her lipid profile. Otherwise, she is very happy with her progress so far and is keen to lose more weight, as well as maintain her healthy habits.
You agree to see each other again in 3 months with repeat blood work.
Referral
You should consider referring a patient to the renal services if there is:
- Progressive CKD, especially once EGFR drops below 45
- Evidence of intrinsic renal disease e.g. glomerulonephritis – this might be picked up on MSU
- Resistant hypertension
- Diagnostic uncertainty.
CKD in the context of a terminal illness may not be appropriate for further workup and may not warrant a referral.
Take home messages
- Early diagnosis is key – this can reduce long-term complications.
- Identify high-risk individuals who require screening.
- Treat underlying risk factors, such as glycaemic control, hypertension, and lifestyle factors.
- Use appropriate medications to mitigate risk, e.g. ARBs in microalbuminuria.
- Avoid nephrotoxic medications.
This MedCase was written by Dr Pulasthi Mithraratne, MBChB, PGDipPaed, FRNZCGP, with review by Prof. Bruce Arroll.
References
Patient resources
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