renal tubular disorders

Question 1

what is renal blood flow

Answer 1

1250ml/min

Question 2

what is urine flow rate

Answer 2

1ml/min

Question 3

proximal tubule disorders

Answer 3

• Active reabsorption of multiple solutes
• Sodium gradient generated by Na/K ATPases
• Vulnerable to hypoxia and toxicity

Disorders: renal glycosuria (glucose), Aminoacisurias (AA), hypophosphataemic rickets (phosphate), Proximal renal tubular acidosis (bicarbonate), Fanconi syndrome (multiple)

Question 4

loop of henle disorders

Answer 4

Barrter’s syndrome:
o Defect: NKCC2, ROMK, ClCKa/b, Barrtin
o Mechanism: Failure of sodium, potassium and chloride cotransport in thick ascending limb.

Question 5

disorders of distal tube and collecting duct

Answer 5

Gitelman’s syndrome (defect NCCT)
Distal (type 1) renal tubular acidosis
type 4 renal tubular acidosis
nephrogenic diabetes insipidus

Question 6

actions of aldosterone

Answer 6

• Steroid hormone – predominantly acts on transcription
• Increase expression of ENaC, Na/K ATP-ase
• Mineralocorticoid receptor also activated by cortisol
• Cortisol entry to renal tubular cells prevented by 11-beta hydroxysteroid dehydrogenase

Question 7

what does excessive aldosterone activity cause

Answer 7

sodium retention, hypertension and hypokalaemic alkalosis