Page 90 - Clinical Biochemistry

When should you assess renal function?

Older age

• Family history of Chronic Kidney disease (CKD)
• Decreased renal mass
• Low birth weight
• Diabetes Mellitus (DM)
• Hypertension (HTN)
• Autoimmune disease
• Systemic infections
• Urinary tract infections (UTI)
• Obstruction to the lower urinary tract
• Drug toxicity

Renal function tests may be grouped into:

Glomerular function tests Tubular function tests

1. Measurement of GFR:

• Clearance tests Urine analysis

2. Serum non-protein Nitrogen (NPN) • Appearance
• Specific gravity and osmolality
• Creatinine (CR) • pH
• Urea • Glucose
• Amino acids (AAs) • Protein
• Uric acid • Aminoaciduria
• Ammonia • Urinary sediments

3. Proteins in urine (Proteinuria)

Biochemical Tests of Renal Function

Measurement of GFR

• GFR is the rate (volume per unit of time) at which ultra-filtrate is formed by the glomerulus.
• Expressed in ml/min
• Normal GFR = 90-120 ml/min/1.73m2
• Best estimate of kidney glomerular function