Lab Tests related to Kidney Function

Serum Creatinine-

indictive of muscle breakdown.

Only increased in kidney disease

loss of 50% of renal function causes and elevation

Should remain constant in older adults unless they have renal disease

Blood Urea Nitrogen-

breakdown of protein in the liver creating a byproduct “urea nitrogen” which the kidneys excrete.

Elevated suggests renal disease

Can be altered due to dehydration, infection, chemotherapy, steroid therapy

Microalbumin/creatinine ratio-

Healthy kidneys keep albumin in the blood, while damaged kidneys let it leak into urine. Doctors use this test to catch early signs of kidney damage, mostly in people with diabetes or high blood pressure.

Normal: Less than 30 mg/g of creatinine.

microalbuminuria (Moderate increase): 30 to 300 mg/g, signaling early kidney

stress or damage.

Macroalbuminuria (High increase): Over 300 mg/g, pointing to more advanced

kidney disease.

Urinalysis

Evaluates waste products from the kidney and detects urologic disorders

Glomerular Filtration Rate

It is a calculation from serum creatinine, age, and sex and measures how well your kidneys filter waste from your blood. GFR > 90: Healthy kidneys. GFR < 60: May indicate kidney disease, especially if it persists for over 3 months. GFR < 15: May signal kidney failure, requiring dialysis or transplant.

Stage 1

Minimal kidney damage when GFR within expected reference range (greater than 90 mL/min)

Stage 2:

Mild kidney damage with mildly decreased GFR (60 to 89 mL/min)

Stage 3:

Moderate kidney damage with moderate decrease in GFR (30 to 59 mL/min)

Stage 4:

Severe kidney damage with severe decrease in GFR (15 to 29 mL/min)

Stage 5:

Kidney failure and end-stage kidney disease with little or no glomerular filtration (less than 15 mL/min)