What are the diagnostic criteria and treatment options for a patient with risk factors for Chronic Kidney Disease (CKD), such as diabetes, hypertension, or a family history of kidney disease, presenting with impaired renal function?

Chronic Kidney Disease Diagnosis

CKD is diagnosed by either eGFR <60 mL/min/1.73 m² OR albuminuria (UACR ≥30 mg/g) persisting for at least 3 months, and all patients with diabetes, hypertension, age >60 years, cardiovascular disease, or family history of kidney disease should be screened immediately with both tests. 1

Who Should Be Screened

Mandatory screening populations include: 1, 2

• Diabetes mellitus - the leading cause of CKD in the United States, accounting for 30-40% of cases 3, 1
• Hypertension - present in 91% of CKD patients and dramatically accelerates kidney damage 1
• Age >60 years - CKD prevalence increases substantially with advancing age 1
• Family history of kidney disease - individuals with affected family members have significantly increased CKD risk 1, 2
• Cardiovascular disease - present in 46% of CKD patients 1
• Obesity - established independent risk factor for CKD development 1

Do NOT screen asymptomatic adults without these risk factors - the evidence is insufficient and potential harms from false positives outweigh benefits in low-risk populations. 1

Diagnostic Testing

Measure BOTH tests simultaneously on initial evaluation: 1

1. Estimated GFR (eGFR) - calculated from serum creatinine using validated equations (CKD-EPI 2021) 1
2. Urinary albumin-to-creatinine ratio (UACR) - on random spot urine sample, preferably first morning void 1, 4

Critical: Both tests provide independent prognostic information for cardiovascular events, CKD progression, and mortality. Never rely on serum creatinine alone. 1

Confirming Chronicity

Repeat abnormal tests within 3 months to confirm persistence and distinguish CKD from acute kidney injury. 3, 1 Two out of three specimens collected over 3-6 months should be abnormal before confirming CKD diagnosis. 4

CKD Staging and Classification

CKD stages are defined by eGFR and presence of kidney damage: 3

• Stage 1: eGFR ≥90 mL/min/1.73 m² WITH evidence of kidney damage (albuminuria or other markers)
• Stage 2: eGFR 60-89 mL/min/1.73 m² WITH evidence of kidney damage
• Stage 3a: eGFR 45-59 mL/min/1.73 m²
• Stage 3b: eGFR 30-44 mL/min/1.73 m²
• Stage 4: eGFR 15-29 mL/min/1.73 m²
• Stage 5: eGFR <15 mL/min/1.73 m² (kidney failure)

Albuminuria categories: 3, 4

• Normal: UACR <30 mg/g
• Moderately increased (microalbuminuria): UACR 30-300 mg/g
• Severely increased (macroalbuminuria): UACR >300 mg/g

Determining Underlying Cause

Systematically evaluate for: 1

• Diabetic kidney disease - typically develops after 10 years in type 1 diabetes but may be present at diagnosis in type 2 diabetes 3, 1
• Hypertensive nephrosclerosis - especially with history of poorly controlled blood pressure or cerebrovascular events 1
• Nephrotoxin exposure - NSAIDs, lithium, calcineurin inhibitors, aminoglycosides, heavy metals 1
• Glomerulonephritis - suggested by hematuria, pyuria, or casts on urinalysis 1
• Obstructive uropathy - consider renal ultrasound if indicated 1

Treatment Priorities

Blood Pressure Management

Target blood pressure <130/80 mmHg in ALL CKD patients. 1, 5

For UACR 30-299 mg/g (moderately increased albuminuria) WITH hypertension: Initiate either ACE inhibitor or ARB. 1, 6

For UACR ≥300 mg/g (severely increased albuminuria): ACE inhibitor or ARB is strongly recommended REGARDLESS of blood pressure level. 1, 7 Losartan is specifically FDA-approved for diabetic nephropathy with elevated serum creatinine and proteinuria (UACR ≥300 mg/g) in type 2 diabetes with hypertension, reducing progression to doubling of serum creatinine or end-stage renal disease. 7

Common pitfall: Do NOT discontinue ACE inhibitors or ARBs for minor increases in serum creatinine (<30%) in the absence of volume depletion. 1 Do NOT combine ACE inhibitors with ARBs - this increases adverse events without additional benefit. 1

Cardiovascular Risk Reduction

Initiate statin therapy for all CKD patients - cardiovascular mortality risk is 5-10 times higher than risk of progression to end-stage kidney disease. 1

Diabetes Management

For diabetic patients with CKD and eGFR ≥20 mL/min/1.73 m²: Consider SGLT2 inhibitors with demonstrated kidney and cardiovascular benefits. 1 Optimize glucose control to slow CKD progression. 1

Avoid Nephrotoxins

Identify and eliminate exposure to: 1, 8

• NSAIDs
• Contrast agents (use with caution)
• Aminoglycosides
• Other nephrotoxic medications

Monitoring Frequency Based on Risk Stratification

The combination of eGFR and albuminuria determines monitoring intensity: 1

• Low risk (Stage 1-2 with UACR <30 mg/g): Annual monitoring
• Moderate risk (Stage 3a with UACR <30 mg/g OR Stage 1-2 with UACR 30-300 mg/g): 2 times per year
• High risk (Stage 3b with UACR <300 mg/g OR Stage 3a with UACR 30-300 mg/g): 3 times per year
• Very high risk (Stage 3b-4 with UACR >300 mg/g): 4 times per year AND nephrology referral

Screening for CKD Complications

When eGFR falls below 60 mL/min/1.73 m² (Stage 3 or greater), screen for complications every 6-12 months: 3, 1

• Electrolyte abnormalities - serum sodium, potassium, chloride, bicarbonate
• Metabolic acidosis - serum bicarbonate
• Anemia - hemoglobin; iron studies if indicated
• Metabolic bone disease - serum calcium, phosphate, intact PTH, 25-hydroxyvitamin D
• Volume overload - blood pressure, weight, physical examination at every visit

Nephrology Referral Indications

Refer immediately when: 1, 4

• eGFR <30 mL/min/1.73 m² (Stage 4 or higher)
• Continuously increasing urinary albumin levels despite optimal management
• Continuously decreasing eGFR or rapid decline in kidney function
• Uncertainty about etiology or atypical features suggesting non-diabetic kidney disease
• Active urinary sediment (hematuria, pyuria, casts)
• Difficulty managing CKD complications (refractory hypertension, hyperkalemia, metabolic acidosis)
• Persistent proteinuria >1,000 mg/24 hours
• Absence of diabetic retinopathy in type 1 diabetes with presumed diabetic kidney disease