Overview of Renal Diseases

Question 1

How do we measure kidney function?

Answer 1

Blood tests: creatinine and formulae

Urine output

Elimination of radioisotopes

Question 2

Give some examples of renal syndromes?

Answer 2

1. Asymptomatic proteinuria
2. Nephritic syndrome
3. Acute kidney injury
4. Nephrotic syndrome
5. Haematuria
6. Chronic kidney disease

Question 3

What does a kidney biopsy provide?

Answer 3

Kidney biopsy provides a histological description which is compatible with a clinical condition and then may direct specific treatments

Question 4

What is acute kidney injury?

Answer 4

Acute kidney injury (AKI) is where your kidneys suddenly stop working properly. It can range from minor loss of kidney function to complete kidney failure.

Question 5

Pre-renal causes are possible

What are the effects of Hypovolaemia, a decrease in perfusion, and drugs

Answer 5

Hypovolaemia:
Haemorrhage
Diarrhoea/vomiting

↓Perfusion:
Septic shock
Cardiac failure

Drugs:
Angiotensin-converting inhibitors
Non-steroidal anti-inflammatory drugs

Question 6

What are the 3 compartments where renal dysfunction can occur?

Answer 6

Vascular

Tubulointerstitial

Glomerular

Question 7

Give some examples of vascular disease

Answer 7

Hypertensive nephrosclerosis
- hyalinosis, fibrointimal thickening, tubular atrophy, ischaemic shrunken glomeruli

Renal artery stenosis
Atheroemboli
Thrombotic microangiopathy
Vasculitis

Question 8

Give some examples of Tubulointerstitial disease

Answer 8

Acute tubular injury

Acute tubulointerstitial nephritis:
Infectious
Non infections
Allergic

Chronic tubulointerstitial nephritis

Question 9

How do we analyse glomerular diseases?

Answer 9

Urine analysis (blood & protein)

Proteinuria quantified by:
urine albumin:creatinine ratio
urine protein:creatinine ratio

Question 10

What are the principles of glomerular disease?

Answer 10

Distinguish between 1° and 2° disease.
Whether 1° or 2°, limited response to injury (5 clinical syndromes).
Consider 1° under headings of clinical syndrome, histopathology, pathogenesis.
Difficult subject:
Often no good clinicopathological correlation
Terminology
Ignorance of pathogenesis in many cases.

Question 11

What occurs in nephrotic syndrome?

What are the causes?

Answer 11

Heavy proteinuria (>3-5 gm/day; ACR > 100)
Hypoalbuminaemia (<30 g/L)
Oedema

Plus: frothy urine, hypercoagulability, hypercholesterolaemia

Causes: minimal change disease, membranous nephropathy, focal segmental glomerulosclerosis

Question 12

What causes Nephritic syndrome?

Answer 12

Abrupt onset (over 1-3 days) of:
Haematuria
Proteinuria
Decreased GFR (raised creatinine, oedema, hypertension)

Classical cause: post-streptococcal GN

Question 13

What causes Asymptomatic urinary abnormalities?

Answer 13

Haematuria (cross-referral with Urology)
+-
Proteinuria

Multiple causes, but IgA nephropathy important

Question 14

How is GN (rapid progression) different from nephritic syndrome?

What are the three main groups of GN?

Answer 14

Like nephritic syndrome, but weeks/months

Anti-glomerular basement membrane (Goodpasture) disease
Small vessel anti-neutrophil cytoplasm antibody (ANCA) +ve vasculitis
Miscellaneous conditions -> tuft damage -> fibrin in Bowman’s space

Question 15

How can we manage acute kidney injury?

Answer 15

Correct any pre-renal factors
Relieve obstruction
May need to treat renal factors (stop nephrotoxic drugs, corticosteroids, etc.)
May try and alter natural history of incipient ATN:
Furosemide

Maintain fluid and electrolyte balance
Nutrition
Gastric protection (PPIs)
Expert nursing
Careful with drugs
Watch for (and hopefully prevent) sepsis