What is the best management approach for an adult patient with chronic kidney disease (CKD), impaired renal function (GFR 38), elevated blood urea nitrogen (BUN) and creatinine levels, hypernatremia (sodium 146), and potential history of hypertension or diabetes?

Management of CKD Stage 3b with Elevated BUN and Mild Hypernatremia

Target blood pressure <130/80 mmHg and initiate an ACE inhibitor or ARB as first-line therapy to slow kidney disease progression, while addressing volume status and monitoring for complications. 1

Immediate Blood Pressure Management

Your patient has CKD Stage 3b (GFR 38 mL/min/1.73 m²) and requires aggressive blood pressure control:

• Target BP <130/80 mmHg based on ACC/AHA 2017 guidelines for adults with CKD stage 3 or higher 1
• Consider targeting systolic BP 120-129 mmHg if tolerated, as the 2024 ESC guidelines recommend this tighter target for moderate-to-severe CKD with eGFR >30 mL/min/1.73 m² 1
• The more recent KDIGO 2024 guideline supports the <130/80 mmHg target for CKD patients 1

First-Line Pharmacologic Therapy

Initiate an ACE inhibitor (or ARB if ACE inhibitor not tolerated) as the cornerstone of treatment 1:

• ACE inhibitors are reasonable (Class IIa, Level B-R) to slow kidney disease progression in CKD stage 3 or higher 1
• ARBs may be used if ACE inhibitor causes intolerable cough or angioedema 1
• Do NOT combine ACE inhibitor with ARB - evidence shows harm with combination therapy 1
• Losartan specifically is FDA-approved for diabetic nephropathy with elevated creatinine and proteinuria 2

Critical Monitoring After RAAS Inhibition

• Check serum creatinine and potassium within 1-2 weeks of initiating or titrating ACE inhibitor/ARB 3
• Accept up to 30% increase in creatinine if it stabilizes - this represents hemodynamic changes, not kidney injury 1
• Monitor for hyperkalemia, which can often be managed with dietary modification and diuretics rather than discontinuing the life-saving RAAS inhibition 4

Address the Mild Hypernatremia (Sodium 146 mEq/L)

The sodium of 146 mEq/L suggests mild hypernatremia, which in CKD typically reflects:

• Inadequate free water intake - ensure patient is drinking adequate fluids 5
• Possible volume depletion - assess for orthostatic hypotension before intensifying BP medications 1
• This is NOT severe enough to delay treatment, but warrants monitoring

Elevated BUN Management

BUN of 43 mg/dL with creatinine 1.8 mg/dL (BUN:Cr ratio ~24) suggests:

• Implement dietary protein restriction to 0.8 g/kg/day for CKD G3b-G5 1
• Higher BUN levels independently predict worse renal outcomes even after adjusting for eGFR 6
• Sodium restriction to <2 g/day (<90 mmol/day) to reduce proteinuria and slow CKD progression 1, 7
• Avoid high protein intake >1.3 g/kg/day 1

Additional Cardiovascular Risk Reduction

Statin Therapy

Initiate statin or statin/ezetimibe combination for all adults ≥50 years with eGFR <60 mL/min/1.73 m² 1:

• This is a Class 1A recommendation from KDIGO 2024 1
• Choose regimens to maximize absolute LDL cholesterol reduction 1, 4

SGLT2 Inhibitor Consideration

Consider adding an SGLT2 inhibitor if patient has diabetes or is at high cardiovascular risk 1:

• SGLT2 inhibitors slow CKD progression and reduce heart failure risk independent of glucose management 1
• Can be used with eGFR ≥20 mL/min/1.73 m² 1
• Empagliflozin reduced risk of doubling serum creatinine by 44% in advanced CKD 1

Nonsteroidal MRA (Finerenone)

Consider finerenone if patient has diabetic CKD with albuminuria 1:

• Currently the only nonsteroidal MRA with proven clinical kidney and cardiovascular benefits 1

Monitoring Strategy

Frequency of Follow-up

For CKD G3b (GFR 30-44), monitor 3 times per year 1:

• Serum creatinine, eGFR, electrolytes (especially potassium) 1, 8
• Urinary albumin-to-creatinine ratio to assess for albuminuria 1
• Blood pressure monitoring 3

Define Progression

CKD progression requires both a change in GFR category AND ≥25% decline in eGFR sustained over time 1:

• Small fluctuations are common and don't necessarily indicate true progression 1

Critical Pitfalls to Avoid

• Do NOT use NSAIDs - they are nephrotoxic and will accelerate CKD progression 4
• Avoid nephrotoxic agents including aminoglycosides and minimize contrast dye exposure 4
• Do NOT discontinue ACE inhibitor/ARB for mild creatinine elevation (<30% increase) or mild hyperkalemia - manage these medically 4
• Avoid atenolol for blood pressure control - it is less effective than placebo in reducing cardiovascular events 1
• Monitor for volume depletion if using diuretics, especially in elderly patients 8

Assess for Albuminuria

You must check urine albumin-to-creatinine ratio to guide therapy 1:

• If albuminuria ≥300 mg/g, ACE inhibitor/ARB becomes a Class I recommendation 1
• If albuminuria ≥30 mg/g, target BP becomes <130/80 mmHg (already your target) 1

Lifestyle Modifications

Implement intensive lifestyle interventions alongside pharmacologic therapy 3:

• Sodium restriction to <1500 mg/day (or <2 g/day per KDIGO) 1, 3
• Weight loss if overweight/obese 1, 3
• Aerobic exercise 90-150 minutes/week 3
• Smoking cessation 1
• Moderate alcohol intake (≤2 drinks/day in men, ≤1/day in women) 3

If Patient Has Diabetes

• Target HbA1c ~7.0% to prevent microvascular complications 1
• Do NOT target HbA1c <7.0% if patient is at risk of hypoglycemia 1
• Metformin can be continued with eGFR 30-44, but monitor closely and reassess benefits/risks 1