Page 35 - Clinical Biochemistry

• Renal Ischemia
• Heart failure
• Hypotension
• Acute renal failure
• Obstruction by: Calculi, Tumor, Prostatic

Causes of anuria
• Severe Renal Defect and loss of urine.
• Due to the presence of stone or tumor.

4- PH
• The normal pH level of human urine is around 5–6 nut can vary from 4.5 to 8 depending
on the persons acid base status.
• Urinary pH is also dependant upon the diet of a person.
• Even in abnormal conditions, urine pH mustn’t reach 9, if so or more this will indicate that
urine was kept for a long time & must be rejected.
• Renal physiology has several powerful mechanisms to control pH by the excretion of
excess acid or base.
• In responses to acidosis, tubular cells reabsorb more bicarbonate from the tubular fluid.
• In responses to alkalosis, the kidney may excrete more bicarbonate and decrease hydrogen
ion secretion from the tubular epithelial cells.

Clinical significance of pH
• Determine the existence of metabolic acid base disorder.
• Precipitation of crystals to form stone requires specific pH for each type. Hence, pH control
may inhibit the formation of these stones by control diet.

Crystals found in alkaline urine : Ca carbonate, Ca phosphate.

Crystals found in acidic urine: Ca oxalate.

Acidic urine in : starvation dehydration, diarrhea.