Management of Stage 3B Chronic Kidney Disease
This patient has Stage 3B chronic kidney disease (CKD) with an eGFR of 44 mL/min/1.73 m², requiring systematic evaluation for underlying causes, assessment for complications, medication review, and consideration for nephrology referral. 1
CKD Classification and Staging
The eGFR of 44 mL/min/1.73 m² places this patient in Stage 3B CKD (moderate to severe GFR decrease, range 30-44 mL/min/1.73 m²), which carries increased risk for cardiovascular events, progression to end-stage renal disease, and metabolic complications. 1
The creatinine of 1.51 mg/dL should be interpreted in context of age, sex, muscle mass, and potential confounding factors such as creatine supplementation or high protein intake, as serum creatinine alone does not adequately reflect GFR. 2, 3
Initial Diagnostic Workup
Immediately assess for the cause of CKD and presence of kidney damage markers:
Measure urinary albumin-to-creatinine ratio (UACR) on a spot urine sample to classify albuminuria stage (normal <30 mg/g, moderately increased 30-300 mg/g, severely increased >300 mg/g). 1
Obtain urinalysis to evaluate for hematuria, pyuria, or casts suggesting glomerular disease. 1
If the patient has diabetes, screen for diabetic kidney disease by checking UACR and reviewing glycemic control (HbA1c). 1
Evaluate for hypertension, as blood pressure control is critical to slow CKD progression. 1
Consider renal ultrasound to assess kidney size, rule out obstruction, and evaluate for structural abnormalities. 1
Assessment for CKD Complications
At eGFR <60 mL/min/1.73 m², evaluate and manage potential complications:
Check complete blood count for anemia, as metabolic changes including anemia occur at earlier stages of CKD than previously recognized, particularly in elderly patients. 4
Measure serum calcium, phosphorus, parathyroid hormone (PTH), and vitamin D to screen for mineral bone disorder. 4
Assess serum potassium for hyperkalemia risk, especially if considering renin-angiotensin system (RAS) blockade. 1, 5
Evaluate for metabolic acidosis with serum bicarbonate. 1
Screen for cardiovascular disease risk factors, as CKD independently increases cardiovascular morbidity and mortality. 1
Medication Management
Review and adjust all medications for renal dosing:
Adjust doses of renally cleared medications according to eGFR to prevent drug accumulation and toxicity. 6
Avoid nephrotoxic agents including NSAIDs, which can cause acute deterioration in renal function, particularly in elderly or volume-depleted patients. 5
If the patient has diabetes with hypertension and albuminuria (UACR ≥30 mg/g), initiate an ACE inhibitor or ARB as these are preferred treatments that delay progression of diabetic kidney disease. 1
For patients with UACR ≥300 mg/g or eGFR <60 mL/min/1.73 m² with diabetes and hypertension, ACE inhibitors or ARBs are strongly recommended. 1
Monitor serum creatinine and potassium within 1-2 weeks after starting or adjusting ACE inhibitors/ARBs; a creatinine rise >30% or eGFR drop >50% warrants dose reduction or temporary discontinuation. 6, 5
Avoid dual RAS blockade (combining ACE inhibitor + ARB, or either with aliskiren) as this increases risks of hyperkalemia, hypotension, and acute kidney injury without additional benefit. 5
Prefer loop diuretics over thiazides at this level of renal function for volume management. 6
Blood Pressure and Glycemic Control
Target blood pressure control to slow CKD progression, with ACE inhibitors or ARBs as first-line agents in patients with albuminuria. 1
For diabetic patients, optimize glycemic control (individualized HbA1c targets) as effective hypoglycemic therapy delays diabetic kidney disease progression. 1
Recommend dietary protein restriction to approximately 0.8 g/kg/day in patients with diabetic kidney disease or CKD to reduce hyperfiltration injury. 1
Monitoring Strategy
Establish regular monitoring intervals:
Recheck eGFR and UACR at least annually, or more frequently (every 3-6 months) if CKD is progressive or patient has diabetes. 1
Monitor serum creatinine, potassium, and bicarbonate every 3-6 months or more frequently when adjusting medications affecting renal function. 1, 6
Assess for volume status to avoid both dehydration (which can worsen pre-renal azotemia) and volume overload. 6
Nephrology Referral Criteria
Refer to nephrology for:
eGFR <30 mL/min/1.73 m² for evaluation for renal replacement therapy planning. 1
Serum creatinine >2.5 mg/dL (>250 μmol/L) regardless of eGFR. 1, 6
Rapidly progressive decline in renal function (eGFR decline >5 mL/min/1.73 m² per year or >10 mL/min/1.73 m² over 5 years). 6
Significant proteinuria (UACR >300 mg/g) or nephrotic-range proteinuria (>2220 mg/g). 1
Uncertain etiology of kidney disease or abnormal urinalysis suggesting glomerulonephritis (hematuria with RBC casts, dysmorphic RBCs). 1, 6
Difficult management issues including resistant hypertension, refractory electrolyte abnormalities, or anemia unresponsive to treatment. 1
Common Pitfalls to Avoid
Do not rely solely on serum creatinine to assess renal function, as it is influenced by muscle mass, age, sex, diet, and supplements (particularly creatine). 2, 7
Do not assume "normal" creatinine means normal kidney function, especially in elderly patients or those with low muscle mass who may have significantly reduced eGFR despite creatinine <1.5 mg/dL. 8
Avoid contrast-induced AKI by ensuring adequate hydration before iodinated contrast procedures and considering alternative imaging when possible in patients with eGFR <60 mL/min/1.73 m². 1
Do not withhold ACE inhibitors/ARBs due to mild creatinine elevation (<30% rise), as this is expected and often transient; however, monitor closely for larger increases. 6