Histo: Renal Disease Flashcards
List the major functions of the kidneys.
- Excretion of metabolic waste products and foreign chemicals
- Regulation of fluid, electrolytes and acid/base balance
- Regulation of blood pressure (renin)
- Regulation of calcium and bone metabolism (1,25-dihydroxy vitamin D)
- Regulation of haematocrit (EPO)
List some key anatomical features of the kidneys.
- Retroperitoneal
- T12-L3
- Right kidney lies lower
- Mean length = 11cm
- Normal weight = 115-170g
- 1 million nephrons per kidneys - can lose of lot of nephrons without decrease in funciton
What proportion of cardiac output goes to the kidneys?
20%
By what mechanism is blood filtered through the glomerulus?
- High hydrostatic pressure (60 mmHg)
- Podocytes create a charge-dependent (anionic) and size-dependent barrier
- Filtration rate = 125 ml/min
Describe the role of the following parts of the nephron:
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting duct
-
Proximal convoluted tubule
- Actively absorbs sodium
- Carries out hydrogen exchange to allow carbonate resoprtion
- Co-transport of amino acids, phosphate and glucose
- Reabsorption of potassium
-
Loop of Henle
- Descending limb and thin ascending limb: permeable to water, impermeable to ions and urea
- Ascending limb: actively resorbs sodium and chloride
- This creates a counter-current multiplier that is aligned with the vasa recta
-
Distal convoluted tubule
- Impermeable to water
- Regulates pH by active transport of protons and bicarbonate
- Regulates sodium and potassium by active transport (aldosterone)
- Regulates calcium (PTH, 1,25-dihydroxy vit D)
-
Collecting duct
- Reabsorb water (principal cells, ADH)
- Regulates pH (intercalated cells, proton excretion)
Describe how immune complex deposition can lead to renal disease.
Complex deposition in the glomerulus results in complement and inflammatory cell activation resulting in damage to the kidney
List some signs and symptoms of renal disease.
- Haematuria
- Proteinuria
- Uraemia
- Hypertension
- Oliguria/anuria
- Polyuria
- Oedema
- Colic
List some genitourinary malformations of the kidney.
- Agenesis
- Renal fusion - e.g. horseshoe
- Ectopic kidney
- Renal dysplasia
- PUJ obstruction
- Posterior urethral valve
- Vesicoureteric reflux
- Ureteral duplication
congenital
Outline the presentation of polycystic kidney disease.
- Hypertension
- Haematuria
- Flank pain
What is the inheritance pattern of polycystic kidney disease and which genes are implicated?
Autosomal dominant (most of the time)
Genes: PKD1 and PKD2
NOTE: PKD is associated with an increased risk of berry aneurysms (and subarachnoid haemorrhage)
In which group of renal patients do renal cysts often develop?
Patients with end-stage renal disease who are on dialysis
Cysts are often:
multiple
bilateral
cortical and medullary
NOTE: cystic disease is associated with increased risk of malignancy (papillary renal cell carcinoma)
List the renal syndromes
List some causes of acute renal failure.
- Pre-renal = failure of perfusion (shock, heart failure)
- Renal = ATN, acute glomerulonephritis, thrombotic microangiopathy
- Post-renal = obstruction (enlarged prostate, stones)
What is the most common cause of acute renal failure?
Acute tubular injury
List some causes of acute tubular injury.
Tubular epithelial cells damaged by:
Ischaemia
Toxins (contrast, haemoglobin, myoglobin, ethylene glycol)
Drugs
Which commonly used class of drugs predisposes to acute tubular injury?
NSAIDs - inhibits vasodilatory prostaglandins which predisposes to ATN
How does acute tubular injury lead to reduced GFR?
- Blockage of tubules by casts (dead cells)
- Leakage from tubules into interstitial space
- Secondary haemodynamic changes (due to the blockage/leakage)
dramatic decrease, but potentially reversible + no scarring
What is acute tubulo-interstitial nephritis?
Immune injury to tubules and interstitium
Can be caused by infection (TB) and **drugs **(NSAIDs, antibiotics, diuretics, allopurinol, PPIs)
what drugs cause actue tubulo-interstitial nephritis
Describe the histological appearance of acute tubulo-interstital nephritis.
Heavy interstitial infiltration with eosinophil and granulomas
Consider TB and sarcoid, but most common is drugs