This document discusses the importance of urine testing in clinical laboratories. It describes how urine is produced in the kidneys and excreted from the body. Urine formation occurs through nephrons, which filter blood in the glomerulus and remove waste through tubules. Urine composition and properties can indicate various medical conditions like urinary tract infections or metabolic disorders. Clinical labs use reagent strips and confirmation tests to detect proteins, blood, glucose, and other substances in urine samples in order to diagnose illnesses.

1. The importance of urine testing
in the clinical laboratory
PFC Eaker

2. How is urine produced?
 Produced by the kidneys
 Drained by ureter into bladder
 Urethra brings out urine from bladder

3. Kidneys

4. Nephrons
 Structural and functional unit of the kidney
 Eliminates wastes
 Regulates pH, blood pressure and blood
volume

5. Nephrons

6. Glomerulus
 Basic filtration unit of the kidney
 First place where urine is formed in the
body
 Along with the Bowman’s capsule,
comprises the renal corpuscle
 Overall function of the kidney is measured
by the glomerular filtration rate (GFR),
which is the rate that blood is filtered
through all glomeruli

7. Glomerulus

8. Glomerulus
Bowman’s capsule

9. Glomerulus
Afferent arteriole

10. Glomerulus
Efferent arteriole

11. Glomerulus
Proximal convoluted tubule

12. How is this process controlled?
 Anti diuretic hormone (ADH)
 Concentration of water in the blood decreases
 Increase in the osmotic pressure stimulates the
osmoreceptors in the hypothalamus
 Hypothalamus signals the posterior pituitary gland to
secrete ADH
 Blood carries ADH to the kidneys
 ADH causes the distal convoluted tubules and collecting
ducts to increase water absorption through osmosis
 Urine becomes more concentrated and volume decreases

13. Normal composition
 95% water
 0.4% Sodium
 0.05% Ammonia
 0.6% Phosphates
 2% Urea
 0.2% Sulfate
 Creatine and Urobilinogen in minute
amounts

14. What can urine indicate?
 UTI
 Systemic illness
 Metabolic disorders
 Diabetes
 Pregnancy

15. Symptoms or problems
 Dark, strong smelling urine
 Burning urination
 Oliguria, Polyuria, Anuria
 Glycosuria, Haematuria, Semonorrhoea
 Backache, Lower abdominal pain,
Suprapubic pain

16. Clinical tests
 Reagent strips

17. Clinical tests
 Protein
 Blood
 Leukocytes
 Nitrite
 Glucose
 Ketone
 pH
 Specific gravity
 Bilirubin
 Urobilinogen

18. Protein
 Expected Values: <15mg/dl
 Sensitivity: 15-30mg/dl Albumin
 Limitations: A visibly bloody urine
may cause falsely elevated
results

19. Blood
 Expected values: <0.010 mg/dl or 3 rbc/ul
 Sensitivity: 0.015-0.062 mg/dl
 Limitations: Some medications
may cause false positives

20. Leukocytes
 Expected values: <10 leukocytes
 Sensitivity: 5-15 leukocytes
 Limitations: Elevated glucose,
medications, and contamination
may cause false results

21. Nitrite
 Expected values: <0.075mg/dl
 Sensitivity: 0.06-0.1 mg/dl
 Limitations: Negative results do
not rule out significant bacteriuria

22. Glucose
 Expected values: <30mg/dl
 Sensitivity: 75-125 mg/dl
 Limitations: Ketone bodies reduce
sensitivity of the test

23. Ketone
 Expected values: <2mg/dl
 Sensitivity: 5-10 mg/dl
 Limitations: Highly pigmented
urine may cause false trace
results

24. pH
 Expected values: 4.6-8.0
 Sensitivity: 5-8.5
 Limitations: Bacterial growth may
cause alkaline shift (pH >8.0)

25. Specific Gravity
 Expected values: 1.001-1.035
 Sensitivity: 1.000-1.030
 Limitations: Dependent upon ions
in urine

26. Bilirubin
 Expected values: ~0.02mg/dl
 Sensitivity: 0.4-0.8 mg/dl
 Limitations: bilirubin derived
bile pigments may mask the
bilirubin reaction

27. Urobilinogen
 Expected values: <1.0 mg/dl
 Sensitivity: >0.02 mg/dl
 Limitations: Test pad may react
with interfering substances known
to react with Ehrlich’s reagent

28. Confirmation tests
 Ictotest
 Acetest
 Clinitest

29. Confirmation tests
 Ictotest
 Confirmation test for bilirubin
 Reaction based on combining
a solid diazonium salt with
bilirubin

30. Confirmation tests
 Acetest
 Confirmation test for ketones
 Acetoacetic acid or acetone
in urine or blood reacts with
nitroprusside in presence
of glycine

31. Confirmation tests
 Clinitest
 Used to determine amount of reducing substances
(glucose) in urine
 Copper sulfate in tablet reacts with
reducing substances in urine
converting cupric sulfate to cuprous
oxide
 5-drop method
 2-drop method

32. Questions