LECTURE 8 (24hr urine collection)

Question 1

What are the indications for 24hr urine collections?

Answer 1

• To determine how much creatinine clears through the kidneys
• Used to measure protein, hormones, minerals and other chemical compounds

Question 2

What chemical preservatives can be added to the 24hr urine sample?

Answer 2

• Hydrochloric acid = preservation of a 24hr urine sample for adrenaline, noradrenaline and steroids
• Toluene = forms a thin layer over the surface + acts as a physical barrier for bacteria and air + used for measurement of chemicals
• Boric acid = a general preservative
• Thymol = inhibits bacteria and fungi
• Formalin = preserves formed elements

Question 3

What is the average urine output for adults?

Answer 3

600-2000 ml

Question 4

What are the abnormalities of urinary volume?

Answer 4

• Polyuria = urinary volume is >2000ml (diabetes mellitus, chronic renal failure, diuretic therapy)
• Oliguria = urinary volume is <400ml (acute glomerulonephritis, cardiac failure, dehydration)
• Anuria = urinary output is <100ml (complete urinary tract obstruction)

Question 5

What do the different colours of urine indicate?

Answer 5

• Green = pseudomonas infection, presence of bilirubin or excretion of cytotoxic agents
• Pink/red = blood
• Orange = excess urobiliogen, rifampicin
• Yellow = bilirubin
• Brown = bilirubin

Question 6

What does foamy urine indicate?

Answer 6

• Presence of excess proteins/bilirubin
• Infection
• Stale urine

Question 7

What is the average excretion of proteins in urine?

Answer 7

Up to 150mg in 24 hours

Question 8

What is Proteinuria?

Answer 8

Protein excretion in urine >150mg in 24 hours in adults

CAUSES:
- Glomerular proteinuria = due to increased permeability of glomerular capillary wall
- Tubular proteinuria = due to excretion of low molecular weight proteins which are actively reabsorbed by proximal renal tubules in diseased conditions of tubules
- Overflow proteinuria = “overflows” from plasma into urine
- Hemodynamic proteinuria = alteration of blood flow through glomeruli causes increased filtration of proteins

Question 9

What is Post-renal proteinuria caused by?

Answer 9

Inflammatory or neoplastic conditions in renal pelvis, ureter, bladder, prostate or urethra