Page 96 - Clinical Biochemistry

• After overnight water deprivation, patient is asked to take 1200 ml of water in half hour,
urine specific gravity is measured in samples collected over next 4 hours. At least samples
should show sp.gr. of 1.003 or below

5. Specific proteinuria:
• α1and β2 microglobulin are filtered by glomeruli and reabsorbed by tubular cells.
• Increased protein conc. in urine is sensitive indicator of renal tubular cell damage.
6. Renal glucosuria
• Presence of glucose in urine when blood glucose is normal reflects the inability of tubules

to reabsorb glucose (specific tubular lesion).
7. Aminoaciduria: e.g. cystinuria (inherited metabolic disorder).

Changes in serum analytes in kidney diseases

Total protein and albumin:

• They decreased in CKD due to increased proteinuria. It may be also proteinuria in ARF but
not affect total protein and albumin.

Serum electrolytes:

• Na is decreased and K is increased in CKD (as kidney reabsorb Na in exchange of K)
• Cl and Phosphates are increased in CKD
• Ca is decreased as vitamin D is deficient

Changes in heomogram and urine analysis in kidney disease

• RBCs count and HB is decreased in advanced stages of kidney disease due to deficiency of
erythropoietin

• Urine examination reveals:
1. Proteinuria in both ARF and CKD as well as kidney infection.
2. Presence of RBCs may indicate glomerulonephritis, acute nephritis and kidney infection.
3. Presence of pus cells and nitrites may indicate bacterial infection.