Could This Patient Have Kidney Issues?
Yes, kidney issues could be present, and you must actively screen for them using serum creatinine to calculate eGFR and urine albumin-to-creatinine ratio (UACR), as these tests detect chronic kidney disease (CKD) in its early, asymptomatic stages when intervention is most effective. 1, 2
Why Active Screening is Essential
Early-stage CKD produces no symptoms, making it impossible to detect without laboratory testing. 3, 4 The disease affects 20-40% of people with diabetes and can progress silently to end-stage kidney disease requiring dialysis or transplantation. 1 Early detection prevents progression, reduces cardiovascular complications, and decreases mortality. 3, 4
Required Screening Tests
Primary Tests (Both Required)
- Serum creatinine with eGFR calculation using the 2021 CKD-EPI equation to assess kidney function 1, 5, 2
- Urine albumin-to-creatinine ratio (UACR) from a random spot urine sample to detect kidney damage 1, 2
Interpretation Thresholds
- eGFR <60 mL/min/1.73 m² indicates reduced kidney function 1, 2
- UACR ≥30 mg/g indicates kidney damage (albuminuria) 1, 2
- Confirm abnormal results with repeat testing within 3-6 months, as two of three specimens must be abnormal to diagnose CKD 1, 2
Risk Factors Requiring Screening
Screen immediately if the patient has:
- Diabetes (type 1 or 2) - screen annually starting at diagnosis for type 2, or 5 years after diagnosis for type 1 1, 2
- Hypertension - a leading cause of CKD 1, 6
- Age >60 years 1, 6
- Family history of kidney disease 2, 6
- Cardiovascular disease 1
- Obesity (BMI >35 kg/m²) 1
Additional Evaluation if Screening is Abnormal
Confirm Chronicity (>3 Months Duration)
- Review past creatinine, eGFR, or UACR measurements 2
- Repeat testing after 3 months if no prior data exists 2
- Check for imaging abnormalities or relevant medical history 2
Assess for Complications When eGFR <60 mL/min/1.73 m²
- Complete blood count (anemia) 1, 5
- Electrolytes: sodium, potassium, calcium, phosphorus, bicarbonate 1, 5
- Parathyroid hormone (secondary hyperparathyroidism) 1
- Vitamin D levels 1
- Blood pressure monitoring (target <130/80 mmHg) 1
Determine Underlying Cause
- Urinalysis with microscopy to detect hematuria, pyuria, casts, or crystals 5, 2
- Renal ultrasound to assess kidney size and rule out obstruction 5, 2
- Screen for diabetes (fasting glucose, HbA1c) 2
- Lipid panel 1
When to Refer to Nephrology
Refer immediately if: 1
- eGFR <30 mL/min/1.73 m² 1
- Rapidly declining eGFR or continuously increasing albuminuria 1
- Uncertainty about the cause of kidney disease 1
- Active urinary sediment (red/white blood cells, cellular casts) 1
- Rapidly increasing proteinuria or nephrotic syndrome 1
- Absence of retinopathy in type 1 diabetes with kidney disease 1
Critical Pitfalls to Avoid
Don't Rely on Serum Creatinine Alone
Serum creatinine is insensitive for early CKD detection. 6 Always calculate eGFR using validated equations, as creatinine levels can remain normal until 50% of kidney function is lost. 6
Don't Skip Albuminuria Testing
Up to 40% of diabetic patients with CKD have reduced eGFR without albuminuria. 1 Both tests are required because they detect different aspects of kidney damage and independently predict cardiovascular risk and CKD progression. 1
Don't Ignore Transient Elevations
Exercise within 24 hours, fever, infection, marked hyperglycemia, menstruation, or uncontrolled hypertension can falsely elevate UACR. 1 Repeat testing is essential before confirming CKD diagnosis. 1, 2
Avoid Nephrotoxic Medications
NSAIDs like ibuprofen cause dose-dependent reductions in renal blood flow and can precipitate acute kidney injury, especially in patients with pre-existing kidney disease, heart failure, or those taking ACE inhibitors or diuretics. 7 Advise patients to avoid all nephrotoxic agents, particularly NSAIDs and nephrotoxic herbal medications. 1
Staging and Prognosis
CKD is staged by both eGFR (G1-G5) and albuminuria (A1-A3). 1, 2 Higher stages predict worse outcomes: