Introduction – Chronic Kidney Disease
The prevalence of chronic kidney disease (CKD) is estimated to be about 10%. There are a large number of elderly patients in primary care with mild CKD but without concomitant albuminuria. Most often, this can be considered normal aging. Moderate CKD is also common in the elderly, especially in concomitant cardiovascular disease and diabetes.
However, renal impairment in combination with albuminuria is a strong and independent risk factor for cardiovascular disease, elevating the severity of the renal impairment and also the risk of acute renal failure.
Diagnosis – Chronic Kidney Disease
For the diagnosis of CKD, the patient must have either at least 3 months long renal impairment expressed as eGFR <60 ml/min / 1.73 m 2 or at least one marker for renal injury:
- Persistent hyperalbuminuria (low grade or high grade)
- Pathological urinary sediment
- Pathological anatomy
- Pathological kidney histology
- Underwent kidney transplantation
Calculate eGFR according to MDRD , CKD-EPI or LM rev based on creatinine or cystatin C. These formulas are considered to be equivalent in accuracy at eGFR> 30 ml/min / 1.73 m 2. Cockcroft & Gault’s equation yields worse accuracy and should not be used.
From the age of 40 to 50, GFR drops by about 10 ml/min / 1.73 m 2 per 10-year period. Thus, there are a large number of elderly patients in the population with definitive CKD stage 3, i.e. eGFR <60 ml/min / 1.73m 2. CKD 3 without albuminuria carries a moderately increased risk of cardiac, vascular and renal complications compared to healthy peers.
CKD 3 with concomitant low or high albuminuria carries a high to very high risk of cardiovascular mortality, terminal renal failure (CKD 5), acute renal failure and progressive renal disease compared with healthy peers.
Treatment – Chronic Kidney Disease
The following patient groups are at low risk for rapid uremia progress and should be monitored in primary care. The focus is on blood pressure control and detecting increased albuminuria.
- Age over 70 years
- U-ACR <30 mg / mmol.
- Well regulated blood pressure
- CKD is assessed to be due to nephrosclerosis
The following patient groups are at high risk for rapid uremia progress and should usually be monitored for renal medicine:
- U-ACR> 100 mg / mmol.
- Difficult blood pressure
- Rapidly dropping eGFR
- Diabetic nephropathy
- Suspected system disease
Blood Pressure Control
In case of hypertension with concomitant high-grade hyperalbuminuria, ramipril ( Triatec ) / enalapril ( Renitec ) or candesartan/losartan should be first-hand medications. There is no study showing that ARB is better than ACE inhibitors, but blood pressure reduction is important in itself. Combined treatment with calcium antagonists, eg amlodipine ( Norvasc ) is common. Thiazides are an alternative good treatment but have little effect at eGFR <30 ml/min / 1.73m 2. In those patient groups, slow-acting furosemide in depot form should be given. Well-regulated blood pressure is the single most important factor in slowing down the rate of deterioration of kidney function. Target blood pressure varies depending on whether European or American cardiologists, diabetologists and nephrologists are asked. It is pragmatic to aim at:
- For patients <65 years and / or in proteinuria: ≤ 130/80 mmHg
- For patients ≥65 years: ≤ 140/80 mmHg
However, risk of hypotension (dizziness?) and hypoperfusion (angina?) must be considered. Often, an increase in creatinine is seen after insertion or dose adjustment of RAAS blockade. Check creatinine, potassium, blood pressure and heart rate after 1 week.
- Decrease in eGFR <15%: acceptable.
- Decrease in eGFR> 15%: halve the dose of RAAS blockade. Check creatinine and potassium levels within 1 week or discuss with nephrology.
- If potassium> 5.5 halve the dose of RAAS blockade or discontinue treatment.
Good metabolic control reduces the risk of kidney damage and delays deterioration of kidney function. In the absence of contraindications, metformin is the first choice in type 2 diabetes. Metformin must be temporarily discontinued during gastroenteritis or other risks of dehydration. The following treatment regimen could be utilized:
- eGFR 45-60 ml / min: continue with metformin 1000 mg x 2. Check eGFR 2-4 times / year.
- eGFR 30-45 ml / min: consider refraining from introducing metformin. Maximum dose of metformin 500 mg x 2. Check eGFR 2-4 times / year.
- eGFR <30 ml / min: Discontinue metformin
DPP4 inhibitors, GLP-1 analog Liraglutide and SGLT-2 inhibitors are secondary alternatives in type 2 diabetes. Empagliflozin and canagliflozin have cardiovascular and renal benefits over Liraglutide and can be used in reduced doses down to eGFR 45 ml/min. The American Diabetes Association recommends SGLT2 inhibitors for patients with type 2 diabetes with eGFR 30-60 ml/min. Neither DPP-4 inhibitors, GLP-1 analogs, nor SGLT-2 inhibitors increase the risk of hypoglycemia.
Medications that require caution and / or dose adjustment
- Absolute eGFR (ml/min) should be used when dose adjusting drugs to renal function.
- Caution with NSAID in heart or kidney failure. Preferably prescribe shorter regimens with longer dosing intervals.
- Prescribe a short term cortisone treatment course when treating an acute gout attack.
- Common medications where dose adjustment is important: ARB, ACE inhibitor, aciclovir, ciprofloxacin, digoxin, metformin, spironolactone, and sulfonylureas. Note that excretion of furadantine largely ceases at eGFR <40 ml / min / 1.73m 2.
Follow-Up – Chronic Kidney Disease
- The focus should be on metabolic control, avoiding NSAIDs and dose adjustments based on absolute eGFR.
- Stable CKD in patients >75 years should be checked 1-4 times a year for renal function, albuminuria, blood pressure, and any secondary disorders, for anemia and secondary hyperparathyroidism. Also check cardiovascular status, degree of hydration and weight.
- Follow P-creatinine (eGFR), U-ACR and blood pressure.
- Red flags that should cause admission to nephrologist:
– Increased albumin gradient: U-Alb-Creatinine ratio >100 mg / mmol
– Difficulties in controlling blood pressure
– Rapid reduction of eGFR
– Diabetes with renal impact
– Suspected systemic disease
- In case of manifestation or suspicion of secondary disorders, complete blood count, sodium, potassium, creatinine, albumin, calcium, CRP, urea, glucose, HbA1c, urate, U-ACR, urinary, cystatin C, standard bicarbonate / carbonic acid, phosphate, PTH are checked. Consider contacting a nephrologist.
- Kidney disease. Theory and clinic. N Clyne, B Rippe 2015
- Hallan SI et al. Combining GFR and Albuminuria to Classify CKD Improves Prediction of ESRD J Am Soc Nephrol -, 2009
- Korkeila Lidén. Prevention and protection in diabetes nephropathy. 2013. 110: CCPF
- Moyinhan et al, BMJ 2013; 344 Preventing overdiagnosis: how to stop harming the healthy.
- Melillo G. 2020 ADA Guidelines Include SGLT2 Inhibitors, GLP-1 Receptor Agonists to Treat Comorbidities. AJMC. December 26, 2019.