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.
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
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
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
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