Renal Disease Flashcards
What are the major functions of the kidney?
Excretion of metabolic waste products and foreign chemicals (including drugs).
Regulation of fluid, electrolyte and acid/base balance.
Regulation of blood pressure: Renin
Regulation of calcium and bone metabolism: 1,25 Dihydroxycholecalciferol.
Regulation of haematocrit: Erythropoietin.
Where are the kidneys?
Retroperitoneal.
T12 to L3 on left; right is lower.
Mean length 11cm.
Normal weight 125-170g (male), 115-155g (female)
Receive around 20% of cardiac output.
What is the anatomy of a kidney?
Basic unit is the nephron:
- Glomerulus
- Afferent and efferent arterioles
- Tubules
Approximately one million nephrons per kidney.
Large functional reserve.
Where is blood filtered in the nephron?
Blood is filtered at the glomerulus.
High hydrostatic pressure (60mmHg).
Podocytes create charge-dependent (anionic) and size-dependent barrier.
125 mL/min
Where in the nephron is the filtrate modified?
The filtrate is modified in the tubules
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting tubule
Collecting Duct
What is the function of the proximal convoluted tubule?
The Proximal Convoluted Tubule actively resorbs sodium.
Hydrogen exchange to allow carbonate resorption.
Co-transport of amino acids, phosphate, glucose.
Potassium is also reabsorbed.
What is the function of the Loop of Henle?
The Loop of Henle doubles back on itself.
Descending/thin ascending limb permeable to water but not ions or urea; ascending limb actively resorbs sodium and chloride.
Countercurrent Multiplier; aligned with vasa recta.
What is the function of the distal convoluted tubule?
The Distal Convoluted Tubule is impermeable to water.
Regulates pH via active transport (proton/bicarbonate).
Regulates sodium, potassium via active transport (aldosterone).
Regulates calcium (parathyroid hormone, 1,25 dihydroxycholecalciferol).
What is the function of the collecting duct?
Resorbs water (principal cells, antidiuretic hormone).
Regulates pH (intercalated cells, proton excretion).
What is the relationship between immune complexes and the kidney?
Latticework of antibody and antigen: May be endogenous or exogenous antigens.
May deposit in the glomerulus:
- Inflammatory response
- Complement activation
- Stimulation of inflammatory cells
May deposit at different rates.
May deposits at different sites.
What are signs and symptoms of renal disease?
- Haematuria
- Proteinuria
- Uraemia
- Hypertension
- Oliguria/Anuria
- Polyuria
- Oedema
- Colic
What are examples of renal disease syndromes?
Acute renal failure
Nephrotic syndrome
Microscopic haematuria
Isolated Urinary Abnormalities
Chronic Kidney Disease
What are renal morphological changes?
Glomerulonephritis
Thrombotic microangiopathy
What is the aetiology of renal disease?
Congenital
Systemic Lupus Erythematosus
Amyloidosis
Drugs
Infections
What are examples of genitourinary malformations and the kidney?
- Agenesis
- Renal Fusion (e.g. horse-shoe)
- Ectopic Kidney
- Renal Dysplasia
- Pelvi-ureteric Junction Obstruction
- Ureteral Duplication
- Vesicoureteral Reflux
- Posterior urethral Valves
What is adult (dominant) polycystic kidney disease?
1:500
10% of end-stage renal failure.
Presents in adulthood with hypertension, flank pain and haematuria.
PKD1, PKDS2
Berry aneurysm
In which group of people do kidney cysts develop?
Cysts commonly develop in patients with end stage renal disease who are on dialysis:
- Multiple
- Bilateral
- Cortical and Medullary
What is the association between cystic kidneys and malignancy?
Increased risk of development of malignancy.
7% risk at 10 years.
Papillary renal cell carcinoma.
What is acute renal failure?
Rapid deterioration in renal function (hours, days).
Common, often in the setting of pre-existing disease.
Presentation and prognosis variable.
What are causes of acute renal failure?
Pre-Renal: Failure of perfusion.
Renal: Acute tubular injury, acute glomerulonephritis, thrombotic microangiopathy.
Post-Renal: Obstruction.
What is acute tubular injury?
Commonest cause of acute renal failure. Tubular epithelial cells damaged by:
- Ischaemia
- Toxins (contrast, haemoglobin, myoglobin, ethylene glycol)
- Drugs
Common in critical illness.
Drugs that inhibit vasodilatory prostaglandins predispose e.g. NSAIDs.
What are causes of failure of glomerular filtration?
Blockage of tubules by casts
Leakage of tubules to interstitial space
Secondary haemodynamic changes
What is acute tubulo-interstitial nephritis?
Immune injury to tubules and interstitium. Can also be due to infection and drugs:
- NSAIDs
- Antibiotics
- Diuretics
- Allopurinol
- Proton Pump Inhibitors
Heavy interstitial inflammatory infiltrate with tubular injury. Can see eosinophils, granulomas.