Urinalysis

Question 1

Why does the volume & colour of urine produced by the kidney vary so much?

Answer 1

• varies concentration of irony components according to need to conserve water
• darker color (dehydrated)
• lighter colour (hydrated)
• done via ADH (pituitary hormone) which promotes water reabsorption into the blood in the distal tubule

Question 2

Why does urine always contain urea

Answer 2

• urea = product of broken down amino acids from proteins
• body only uses amount of Protein needed -> rest is broken down
  = body constantly breaking down protein & replacing with others -> urine always contains urea

Question 3

Why are glucose & amino acids reabsorbed in the nephron

Answer 3

• small enough to be filtered from blood at nephron = enter kidney tubules
• body needs & reuses some substances -> special mechanisms evolved in proximal tubules = reabsorb substances from the blood

Question 4

Why can’t the kidney just excrete the filtered plasma without adjusting its content?

Answer 4

• homeostasis would not be maintained

- water & solute levels constantly fluctuating according to environment

Question 5

Interpretation of results:

Colour

Answer 5

Influenced by

1. Chemical composition
2. Urine concentration
   - vitamin B = intensely yellow colour
   - normal urine = clear

Question 6

Interpretation of results:

Volume

Answer 6

• water intake

- 2 liters daily

Question 7

Interpretation of results:

Specific gravity

Answer 7

(1.005-1.025)

• reflects ability of kidneys to concentrate urine
• higher sp = more concentrated urine
  => excretion of large amounts of salt or urea/ conservation of water by the kidney

Question 8

Interpretation of results:

pH

Answer 8

(5 to 9)

• < 7= acidic — large component of meat in diet
• > 7 = basic — large component of plant-based material in diet & bacterial growth

Question 9

Interpretation of results:

Glucose

Answer 9

(<30mg/dL)

• very small amounts excreted (reabsorbed in proximal convoluted tubule)
• normally -I’ve in urine
• positive result indicates more glucose in the blood being filtered than the kidney can reabsorb

Question 10

Interpretation of results:

Protein

Answer 10

(<15mg/dL)
- very little protein normally present in the urine = not filtered in glomerulus (proteins too large to be filtered at the glomerulus filtration barrier)
- amino acids reabsorbed in proximal convoluted tubule
- normally: no protein in urine
(If protein):
1. Kidney disease
2. Strenuous exercise

Question 11

Interpretation of results:

Blood

Answer 11

Positive test = positive for red blood cells OR haemoglobin

• either = abnormal
• test = positive even if no cells are visible under microscope
• blood:
  
  1. Trauma to renal tubule, ureter, bladder or urethra

Question 12

Interpretation of results:

Ketones

Answer 12

• normal: no ketones detectable in urine
• ketones in blood= burning body fat for energy
• presence in urine:
  
  1. Ketoacidosis
  2. Fasting
  3. Strenuous exercise
  4. Pregnancy
  5. Metabolic disorder (I.e. diabetes)

Question 13

Interpretation of results:

Bilirubin/ urobilinogin

Answer 13

• bilirubin = normally negative
• bilirubin & uro = breakdown of red blood cells & recycling of haemoglobin in body
  1. Blood cells may be dying too rapidly
  2. May be reduction in liver function required to recycle normal number of red blood cells

Question 14

Interpretation of results:

Nitrite

Answer 14

• product of bacterial reduction of nitrate
• indicates presence of bacterial infection
• normal: no nitrite in urine as urine is sterile
• painful urination= typical of lower urinary tract (urethra and bladder) infections —> travel up to kidney if left untreated
• May be sexually transmitted
• antibiotics used to treat infections
• bacterial culture = important to guide antibiotic therapy

Question 15

Interpretation of results:

Sediment

Answer 15

• common urine sediment = epithelial cells, blood cells, casts & crystals
• white blood cells suggest infection
• small no. Red cells may be present but sig no. Are not
• presence of crystals = increased risk of forming kidney stones
  —> result from excess o slate in diet (nuts, dark green veggies)
  —> made worse by high concentration/ high pH (causes oxalate to precipitate out of solution)
• calcium oxalate stones = most common, but Utica acid and certain other minerals can precipitate out of urine

Question 16

Renal artery

Answer 16

Carries blood to kidney

Question 17

Renal vein

Answer 17

Carries blood away from kidney

Question 18

Ureter

Answer 18

Urine drained by ureter from kidney into bladder

Question 19

Renal medulla

Answer 19

Tightly packed excretory tubules and associated blood vessels found here

Question 20

Renal pelvis

Answer 20

Urine is collected in the inner renal pelvis

Question 21

Renal cortex

Answer 21

Supplied with blood by renal artery and drained by renal vein

Question 22

Descending limb of the loop of Henle

Answer 22

Reabsorption of water continues as the filtered moves into the descending limb

Question 23

Ascending limb of the loop of Henle

Answer 23

The filtrate reached the tip of the loop and then returns to the cortex in the ascending limb

Question 24

Vasa recta

Answer 24

Hairpin shapes capillaries that serve the renal medulla including the long loop of Henle of juxtamedullary nephrons

Question 25

Distal tubule

Answer 25

Regulates K+ and NaCl concentration of body fluids

Question 26

Glomerulus

Answer 26

Ball of capillaries

Question 27

Proximal tubule

Answer 27

Reabsorption of water, ions and valuable nutrients from filtrate