What is the treatment for microalbuminuria?

Treatment of Microalbuminuria

The first-line treatment for microalbuminuria is an ACE inhibitor or ARB, even in normotensive patients, as these medications have been shown to delay progression to macroalbuminuria and nephropathy beyond their blood pressure-lowering effects. 1

Definition and Diagnosis

• Microalbuminuria is defined as urinary albumin excretion of 30-299 mg/24h or 30-299 mg/g creatinine on a random spot urine sample 1, 2
• Diagnosis requires confirmation with 2 out of 3 abnormal specimens collected over a 3-6 month period due to significant day-to-day variability 1, 2
• Patients should refrain from vigorous exercise for 24 hours before sample collection 1
• First morning void samples are preferred to minimize effects of orthostatic proteinuria 3

Treatment Algorithm

First-Line Therapy

• ACE inhibitors are the first-line treatment for microalbuminuria in both type 1 and type 2 diabetes, even in normotensive patients 1
• If ACE inhibitors are not tolerated, ARBs should be substituted 1
• Losartan is specifically FDA-approved for diabetic nephropathy with elevated serum creatinine and proteinuria in patients with type 2 diabetes and hypertension 4
• Clinical trials have shown losartan reduces proteinuria by 34% and slows the rate of decline in glomerular filtration rate by 13% 4

Glycemic Control

• Optimize glucose control to reduce risk or slow progression of nephropathy 1
• Target HbA1c <7% to minimize risk of progression 5

Blood Pressure Control

• Target blood pressure <130/80 mmHg in all patients with diabetes or kidney disease 1, 5
• If blood pressure targets are not achieved with ACE inhibitors or ARBs alone, add other antihypertensive agents 1
• Non-dihydropyridine calcium channel blockers, β-blockers, or diuretics can be used as additional therapy in patients already treated with ACE inhibitors or ARBs 1

Dietary Modifications

• Protein restriction to 0.8 g/kg body weight/day (approximately 10% of daily calories) is recommended for patients with microalbuminuria 1
• Further restriction to 0.6 g/kg/day may be beneficial when GFR begins to decline 1
• Low-salt diet should be instituted to help control blood pressure 5

Monitoring and Follow-up

• Monitor microalbumin excretion every 3-6 months to assess response to therapy 2
• A reduction in albuminuria of ≥30% is considered a positive response to therapy 2
• Measure serum creatinine and potassium levels when using ACE inhibitors or ARBs to monitor for hyperkalemia 1
• Measure serum creatinine at least annually to estimate GFR and stage CKD if present 1

Special Considerations

• ACE inhibitors and ARBs are contraindicated in pregnancy 3
• Use these medications with caution in patients with advanced renal insufficiency due to risk of hyperkalemia 1
• Consider referral to a nephrologist when GFR falls below 60 ml/min/1.73 m² or difficulties occur in managing hypertension or hyperkalemia 1

Clinical Significance

• Microalbuminuria is an early marker of diabetic nephropathy and predicts progression to gross proteinuria within 6-14 years 6
• It's also an independent marker of increased cardiovascular risk 6, 7
• Early intervention can potentially slow or prevent progression to overt nephropathy with careful glycemic and blood pressure control 7