Urine chemistry

urine chemistry

specific gravity = 1.00 for distilled water    

• increases with solutes   
• measures concentrating ability of kidney
• nl = 1.003 to 1.035

nitrites - positive in gram negative UTIs  (bacteria convert nitrates to nitrites

erythrocytes - positive in UTIs, glomerulonephritis, polycystic kidney disease, malignancies

• also detects free Hb in urine (hemolytic anemia, burns, rhabdomyolysis (muscle damage)  (foot stike anemia in long distance runners)

Leukocytes  - positive indicates granulocytes

Protein - referenced to creatinine; i.e., albumin/creatinine ratio - <17mg albumin/g protein in males; <25 in females

• positive in nephrotic syndrome, pre-eclampsia, infection, inflammation, etc.

Glucose -  present only in diabetes mellitus


Bilirubin - positive in biliary obstruction; some types of liver disease


Ketones - positive in carbohydrate deprivation (Adkin's diet), ketoacidosis

Urobilinogen - correlates with bilirubin

Specific Gravity  - dillution of urine


pH -  nl range = 4.5- 8.0

Microscopic Exam

• squamous epithelial cells - normal if not too many
• transitional epithelia cells - smaller, rounder, come from upper UT, increase with UTI
• renal tubular epithelial cells - seen in nephritis  PPT states "about the size of a WBC"  but picture shows them as much smaller. 
• RBCs
• Yeast

UTI 

Renal Casts

• form when flow through tubules is stopped.
• waxy casts associated with end-stage renal disease

  
Crystals