What are the management and evaluation steps for a 32-year-old patient with impaired renal function (eGFR of 73) and no explicit medical history or current symptoms?

Management of eGFR 73 in a 32-Year-Old Patient

An eGFR of 73 mL/min/1.73 m² in a 32-year-old represents Stage 2 CKD (mild decrease in GFR) and warrants immediate investigation to identify the underlying cause, as this level of renal impairment is abnormal for this age and suggests pathology rather than normal aging. 1

Initial Diagnostic Workup

The following tests must be obtained immediately to characterize the kidney disease:

• Urine albumin-to-creatinine ratio (UACR) on a morning spot urine sample to assess for albuminuria (normal <30 mg/g, microalbuminuria 30-300 mg/g, macroalbuminuria >300 mg/g) 1, 2
• Urinalysis with microscopy to evaluate for hematuria, pyuria, casts, or other abnormalities suggesting glomerular disease, infection, or interstitial nephritis 1, 2
• Repeat serum creatinine and eGFR in 3 months to confirm chronicity, as CKD requires abnormalities present for >3 months 1, 2
• Complete metabolic panel including electrolytes, bicarbonate, calcium, and phosphate to assess for CKD complications 2
• Complete blood count to evaluate for anemia 2
• Renal ultrasound to assess kidney size, echogenicity, and rule out structural abnormalities or obstruction 1, 2

Critical History and Medication Review

Obtain detailed information about:

• Medication and supplement use, particularly NSAIDs, proton pump inhibitors, lithium, and creatine supplements (which can falsely elevate serum creatinine and lower calculated eGFR) 3
• Family history of kidney disease, particularly polycystic kidney disease, hereditary nephritis (Alport syndrome), or other genetic conditions 1, 2
• Diabetes, hypertension, or autoimmune disease as these are common causes of CKD even in young adults 1, 2, 4
• Recent acute illnesses, volume depletion, or nephrotoxin exposure that could indicate acute kidney injury 1

Risk Stratification Based on UACR Results

The management intensity depends critically on albuminuria status:

• If UACR <30 mg/g (normal): This patient has isolated reduced eGFR without proteinuria. Investigate for secondary causes including medications, obstruction, or congenital abnormalities. Monitor eGFR every 6-12 months. 1, 2

• If UACR 30-300 mg/g (microalbuminuria): This indicates Stage 2 CKD with moderate risk. Optimize blood pressure to <130/80 mmHg, screen for diabetes, and consider ACE inhibitor or ARB if hypertensive. Monitor eGFR and UACR every 3-6 months. 1, 4

• If UACR >300 mg/g (macroalbuminuria): This indicates high-risk CKD requiring nephrology referral for possible kidney biopsy to establish diagnosis and guide immunosuppressive therapy if indicated. 1, 2

Blood Pressure and RAAS Blockade Management

• Target blood pressure <130/80 mmHg using lifestyle modifications (sodium restriction <2 g/day, weight optimization to BMI 20-25 kg/m², regular exercise) 1, 2
• ACE inhibitors or ARBs are recommended only if the patient has hypertension AND albuminuria ≥30 mg/g, as these agents reduce proteinuria and slow CKD progression 1
• ACE inhibitors or ARBs are NOT recommended for patients without hypertension to prevent CKD development, as trials showed no benefit and potential harm 1
• An initial decline in eGFR of 10-20% after starting ACE inhibitor/ARB is acceptable and does not require discontinuation unless accompanied by hyperkalemia or excessive decline 5, 6
• Never combine ACE inhibitors with ARBs, as this increases adverse events (hyperkalemia, acute kidney injury) without additional benefit 1

Nephrology Referral Criteria

Immediate nephrology referral is indicated if any of the following are present:

• Rapid decline in eGFR >5 mL/min/1.73 m² per year or sustained decline >20% 1, 7
• Proteinuria >1 g/day (UACR ≥60 mg/mmol or PCR ≥100 mg/mmol), as kidney biopsy may be indicated 1
• Unexplained low eGFR in a young patient (age <40) without obvious cause 1
• Active urinary sediment (dysmorphic RBCs, RBC casts) suggesting glomerulonephritis 2
• Suspected hereditary kidney disease based on family history 1
• Inability to tolerate renal protective medications or difficulty achieving blood pressure goals 1

Common Pitfalls to Avoid

• Do not assume this is "normal aging" – a 32-year-old should have eGFR >90 mL/min/1.73 m², and age-related decline begins at 30-40 years at only 1% per year 1, 5
• Do not start ACE inhibitor/ARB empirically without confirming hypertension and/or albuminuria, as this may cause harm without benefit 1
• Do not use serum creatinine alone to assess renal function, as it is influenced by muscle mass, diet, and supplements 1, 3, 8
• Do not delay nephrology referral if proteinuria is significant or eGFR declines rapidly, as early intervention improves outcomes 1, 7
• Avoid nephrotoxic medications including NSAIDs, aminoglycosides, and contrast agents when possible 2

Monitoring Strategy

For Stage 2 CKD with eGFR 60-89 mL/min/1.73 m²:

• Repeat eGFR and UACR every 3-6 months depending on stability and albuminuria level 1, 2
• Annual screening for CKD complications including anemia (hemoglobin), metabolic acidosis (bicarbonate), hyperparathyroidism (PTH, calcium, phosphate), and vitamin D deficiency once eGFR approaches 60 mL/min/1.73 m² 2
• Cardiovascular risk reduction with statin therapy if indicated by standard risk calculators, as CKD increases cardiovascular mortality risk 1, 2, 4