Basic Renal

Question 1

Define dysuria & what are its causes?

Answer 1

Pain on micturition caused by;

• Inflammation involving urethra (urethritis) or bladder (cystitis)
• Inflammation of the vagina/ glans penis.

Question 2

Define polyuria & what are its causes?

Answer 2

Excessive urine output of greater than 2.5-3L in 24hr caused by;

• Polydipsia (excessive thirst leading to increased fluid intake >3L a day)
• Solute diuresis (eg hyperglycaemia with glycosuria)
• Diabetes insipidus
• CKD

Question 3

Define oliguria, what are its cuases & how is it managed?

Answer 3

Oliguria is low urine output of 100<400ml/day.

Caused by;

• Physiological
  
  • Hypotension
  • Hypovolaemia
• Acute kidney injury
• Bilateral uteric or bladder outflow obstruction

It is managed in 3 steps;

• Exclude obstruction
  
  • Catheter/ flush catheter
  • USS to exclde pelvicalyceal (above bladder) dilatation
• Assess hypovolaemia
  
  • BP, pulse, jugular venous pressure, urinary electrolytes
  • Fluid challene
• Management of established acute kidney injury

Question 4

How do you calculate GFR?

Answer 4

=1.23 x (140 - age) x (weight in kg)

Serum creatinine

In women, use 1.04 instead of 1.23

Question 5

Outline the renin-angiotensin-aldosterone system

Answer 5

1. Low renal perfusion (juxtaglomerular apparatus)
2. Renin release
3. Converts angiotensinogen (from liver) to angiotensin 1
4. Angiotensin 1 is converted to angiotensin 2 (via ACE)

Question 6

What are the functions of angiotensin 2?

Answer 6

Functions of angiotensin 2;

1. Massive vasoconstriction
2. ADH secretion from posterior pituitary
3. Aldosterone secretion from adrenal gland cortex
4. Sympathetic activity increase
5. Renal
   
   • Na⁺Cl^- reabsorption in proximal tubule (and hence H₂O)
   • K⁺ exretion

Question 7

What are the functions and mechanism of renin?

Answer 7

Mechanism;

1. Macula densa detects changes in volume delivery to distal tubule
   
   • MD stimulates juxtaglomerular cells to release renin
2. Renin secretion is also stimulated by sympathetic nervous stimulation
3. Low BP detected by baroreceptors in the juxtaglomerular apparatus

Function;

• Converts angiotensinogen (from liver) to angiotensin 1

Question 8

• What are the function and mechanism of ADH?

Answer 8

Function;

• Insert aquaporin-2 channels into distale tubule & collective ducts allowing water reabsorption

Mechanism;

• Released by posterior pituitary due to;
  
  • Inc osmolarity of plasma
  • Low plasma volume
  • Angiotensin 2
• Inhibited by;
  
  • Atrial natriuretic peptide (via ANP inhibiting angiotensin-2)

Question 9

What are the functions & mechanism of aldolsterone?

Answer 9

Functions;

• Upregulates and activates basolateral Na⁺/K⁺ pumps
• Upregulates epithelial sodium channels
• Secretes K⁺
• Secretes H⁺ for Na⁺ (regulating plasma bicarbonate HCO₃^-)

Mechanism;

• Stimulated by angiotensin 2
• Released from adrenal gland cortex

Question 10

Kidney Anatomy

Question 11

Glomerular Histology

Question 12

Nephron Anatomy