L10 - Biochemical investigation of urogenital diseases (I)

Question 1

3 major functions of the kidney

Answer 1

1) Regulation of water, electrolyte and acid-base balance
2) Excretion of waste products of intermediary metabolism, e.g., urea, creatinine, uric acid, phosphate, sulphate and organic acids
3) Production and elaboration of hormones, e.g., renin, erythropoietin, 1, 25 - (OH)₂ - D3

Question 2

Renal Blood Flow (value)

Answer 2

1200 mL/min

~20% of cardiac output

RBF = RPF / (1 - hematocrit)

Question 3

Renal Plasma Flow

Answer 3

RPF = RBF * (1 - hematocrit)

important in calculating filtration fraction

Question 4

Glomerular filtrate rate

Answer 4

125 mL/day; 180 L/day

Question 5

Filtration fraction

Answer 5

Filtration fraction = Glomerulat filtrate rate / renal plasma flow

FF ~ 20%

Question 6

Glomerular blood hematocrit

Answer 6

~ 55%

Question 7

Urine formation (value)

Answer 7

1 mL/min

~ 1.5 L/day

Question 8

Water reabsorption percentage (figures of total reabsorption and in proximal convoluted tubules)

Answer 8

• 99% H20 in glomerular ultrafiltrate reabsorbed by the kidney
• 65% occurs in the proximal renal tubules accompanied by Na+ and Cl- reabsorption

Question 9

Urea, SO₄^2-, PO₄^2- and other waste products of metabolism (figure)

Answer 9

~ 550 mOsm/day

Question 10

Maximal Urinary Concentration attainable

Answer 10

~ 1,300 - 1,400 mOsm/L

Question 11

Minimal Volume of Urine Water

Answer 11

~ 400 mL/day

Question 12

Calculating Obligatory water loss

Answer 12

Obligatory water loss/minimal volume of urine water

= Rate of metabolic waste production / Maximal urinary concentration attainable

= (550 mOsm/day) / (1400 mOsm/L)

~ 400 mL/day

Question 13

Oliguria (definition)

Answer 13

the production of abnormally small amounts of urine.

100 mL/day < urine produced < 400 mL/day

Question 14

Anuria (definition)

Answer 14

nonpassage of urine

urine produced < 100 mL/day

Question 15

Problem of urine < 400 mL/day

Answer 15

Azotaemia is inevitable with Urinary Output < 400 mL/day

Question 16

Azotaemia (definition)

Answer 16

A medical condition characterized by abnormally high levels of nitrogen-containing compounds in blood

Azotaemia is inevitable with Urinary Output < 400 mL/day