What are the treatment approaches for chronic kidney disease (CKD) and when to refer for acute kidney injury (AKI)?

Treatment of Chronic Kidney Disease and Referral Criteria for AKI

CKD Treatment Approach

The treatment of chronic kidney disease centers on slowing progression through blood pressure control with ACE inhibitors or ARBs, managing proteinuria, optimizing glycemic control in diabetics, and addressing metabolic complications, while nephrology referral is indicated for eGFR <30 mL/min/1.73 m², rapid progression (>5 mL/min/1.73 m² decline per year), or significant proteinuria (>1 g/day). 1, 2, 3

Core Pharmacological Interventions

• Blood pressure control using ACE inhibitors or ARBs has the strongest evidence for slowing CKD progression and should be prioritized as first-line therapy 3
• Target blood pressure should be <130 mmHg systolic for optimal kidney protection 2
• SGLT2 inhibitors provide long-term kidney protection and should be incorporated into treatment regimens, particularly for diabetic kidney disease, despite potential initial eGFR decline 2
• Glycemic control with target HbA1c <7.0% in diabetic patients helps retard progression 2, 3

Management of Metabolic Complications

• Address metabolic acidosis, hyperphosphatemia, and vitamin D deficiency as these represent therapeutic targets that may slow progression 3
• Monitor and manage hyperkalemia and electrolyte abnormalities, particularly as kidney function declines 4
• Implement dietary modifications including sodium and protein restriction under dietitian guidance 2

Lifestyle Modifications

• Encourage physical activity to reduce muscle wasting and improve overall outcomes 4
• Smoking cessation is essential 5
• Dietary adjustments should be individualized based on CKD stage and metabolic status 4

Nephrology Referral Criteria for CKD

Absolute Indications for Referral

Refer immediately to nephrology when eGFR <30 mL/min/1.73 m², as this represents advanced CKD requiring specialist co-management 1, 6, 2

• Rapid progression defined as eGFR decline >5 mL/min/1.73 m² per year mandates specialist evaluation 2
• Abrupt sustained eGFR decrease >20% after excluding reversible causes requires referral 2
• Persistent proteinuria >1 g/day (ACR ≥60 mg/mmol or PCR ≥100 mg/mmol) despite optimal treatment 2
• Urinary red cell casts or RBC >20 per high power field sustained and unexplained 2

Additional Referral Triggers

• Hypertension refractory to 4 or more antihypertensive agents 2
• Persistent serum potassium abnormalities 2
• Recurrent or extensive nephrolithiasis 6, 2
• Hereditary kidney disease 2
• Uncertain etiology of kidney disease (absence of diabetic retinopathy with heavy proteinuria, active urine sediment) 2

Timing Considerations

Late referral (<1 year before renal replacement therapy) is associated with increased morbidity and mortality and must be avoided 6, 2

• When the risk of kidney failure requiring RRT within 1 year is 10-20% or higher, referral should occur 2
• At eGFR of 8 mL/min/1.73 m², the risk of kidney failure requiring RRT within 1 year approaches 100% 6

Exceptions to Referral

Patients with eGFR <30 mL/min/1.73 m² may not require referral if GFR is stable, diagnosis is clear, or very advanced age with short life expectancy is present 2

Management of Acute Kidney Injury (AKI)

When to Refer AKI to Nephrology

Refer AKI to nephrology when features suggest diagnoses other than prerenal azotemia or acute tubular necrosis, or when AKI persists beyond 48 hours with unclear etiology 7, 2

Diagnostic Evaluation for AKI

• Perform renal ultrasound to identify hydronephrosis and obstructive causes as a priority diagnostic step 7
• Urine sediment analysis helps differentiate obstructive from other AKI causes 7
• Assess urine output patterns (anuria or significant oliguria suggests complete obstruction) 7
• Evaluate risk factors including nephrolithiasis history, prostatic hypertrophy, and pelvic malignancy 7

AKI Management Principles

• Treat the underlying cause of obstruction (stones, tumor, stricture) as primary intervention 7
• Avoid nephrotoxic medications during recovery to prevent re-injury 7
• Monitor for post-obstructive diuresis which may cause volume depletion and electrolyte abnormalities 7
• Do not use eGFR equations (MDRD or CKD-EPI) during AKI as they are inaccurate in this setting 7
• Use timed urine creatinine clearance for best available kidney function estimate in persistent AKI 7

AKI to CKD Transition

Acute kidney disease (AKD) is defined as persistence of AKI beyond 7-90 days after initial diagnosis, occurring in approximately 25% of AKI survivors 8

• Do not assume chronicity based on single abnormal eGFR and ACR, as findings could result from recent AKI 1
• Proof of chronicity requires 3-month duration confirmed by repeat measurements, imaging findings (reduced kidney size, cortical thinning), or pathological findings 1
• Monitor for development of AKD if complete recovery doesn't occur after AKI 7

Critical Pitfalls to Avoid

• Never delay nephrology referral for "optimization" when eGFR <30 mL/min/1.73 m² or uremic symptoms are present 6
• Do not discontinue ACE inhibitors or ARBs for minor creatinine increases (<30%) without volume depletion 2
• Avoid assuming stability in patients with uremic symptoms regardless of kidney function stability 6
• Monitor potassium urgently in severe CKD with metabolic acidosis due to life-threatening hyperkalemia risk 6
• Review all medications for renal dosing adjustments as kidney function declines 6, 2
• Recognize non-diabetic kidney disease in diabetic patients (absence of retinopathy, heavy proteinuria, active sediment) 2

Multidisciplinary Care Requirements

Patients with progressive CKD and eGFR <30 mL/min/1.73 m² benefit from multidisciplinary care including nephrology, dietitian, vascular surgery (for dialysis access), transplant evaluation, and social work/psychology support 6, 2

• Provide education about renal replacement therapy options (hemodialysis, peritoneal dialysis, transplantation) and comprehensive conservative care 1
• Initiate advanced care planning for patients with recognized end-of-life care needs 1
• Arrange vascular access planning when eGFR approaches dialysis range 6