Kidney and Urinary Tract Pathology Flashcards
What is the function of the kidneys?
• Eliminate metabolic waste products
• Regulate fluid/ electrolyte balance- sodium
• Regulate acid-base balance
• Produces hormones;
o Renin: fluid balance (RAAS)
o Erythropoietin: stimulates erythrocyte production
Why is Renal Disease a Big Issue?
- 26,000 patients- acute renal failure/year in England; 15% of all hospital admissions
- Most recover, but 10,000 need dialysis (50% mortality)
- 5,500 patients develop chronic renal failure/yr in England- 43,000 patients with CRF in England
- 50% will have a transplant, 40% haemodialysis, 10% peritoneal dialysis (risk peritonitis)
- 2010-2011; 1020 living donor renal transplants, 1667 deceased donor transplants, 7000 patients still on renal transplant waiting list
What are the Presentations of Renal Disease?
- Acute renal failure; unwell, rapid rise in creatinine & urea
- Nephrotic syndrome triad (loss of protein); oedema, proteinuria, hypoalbuminaemia
- Acute nephritis (nephritic syndrome) (loss of blood): oedema, proteinuria, haematuria, renal failure
- Chronic renal failure; slow decline in renal function
- Heamaturia
- Proteinuria
- Progressive decline of renal function as age- accelerated in renal failure
What is the function of different parts of the kidney?
- Afferent- vulnerable to damage
- Bowmen’s capsule- big macromolecules remain in here, glucose & sodium pass through
- So in descending loop of Henle- reabsorption
- But in ascending loop- processes more based on secretion involved (getting rid of extra stuff don’t need)
What is Thrombotic Microangiopathy?
Renal Disease- Vascular Damage
- Blocking blood flow into glomerulus
- Thrombi in capillaries/ arterioles
- Endothelial damage by bacterial toxins, drugs, complement or clotting system abnormalities
- E.g. Haemolytic uraemic syndrome
What is Vasculitis ?
- Acute/ chronic vessel wall inflamm with lumen obliteration
- Various types affect diff calibre vessels
- Vasculitis- small/ large vessels- e.g. Wegner’s granulomatosis (granulamotosis with polyangiosis)
How can an atheroma lead to kidney damage?
Atheroma- lumen narrowing- blood not getting through = ischaemic damage
What is Goodpasture’s syndrome?
autoimmune disease selectively damaging basement membranes= Glomerular Damage
What are the causes of Glomerular Damage ?
Immunological (autoimm destruct of kidney)
• Complexes made elsewhere in body- get stuck in kidney- cause effects (immune response)
• Goodpasture’s syndrome- autoimm disease selectively damaging basement memb
Non-immunological
• Abnormal basement memb- podocytes- abnormal collagen so abnormal basement memb
• Abnormal protein deposition- amyloid can have them with excess Ig’s, Rheumatoids etc- these being deposited continuously (fighting a losing battle)
What are the causes of Tubular Damage ?
- Tubular component particularly vulnerable to ischaemic damage
- Degree of renal tubule damage correlates with renal function
• Ischaemic (caused reduced perfusion= tubular damage);
o Hypotension e.g. shock
o Vessel damage e.g. vasculitis HTN
o Glomerular damage
• Toxic (= tubular damage); o Direct toxins o Hypersensitivity reacs- drugs o Crystal deposits e.g. urate (gout) o Abnormal protein deposition (direct tubular damage) e.g. Ig’s
- NSAIDs Ace control hypertension- are on drugs that cause renal damage but hypertension also causes renal damage
- Ethylene glycol (anti-freeze)- people drink
What does crescentic mean?
Rapidly progressive
What is Nephrotic Syndrome?
Always due to damage to glomerulus
What are the features of Nephrotic Syndrome?
- Oedema (pitting) (fluid stays in circ- oncotic pressure unbalanced as lost proteins keeping fluid in)
- Proteinuria (>3g in 24h)- loosing lots of protein in urea
- Hypoalbuminaemia
- +/- Hypertension (loosing fluid- renin agiotensin system kicks in= increases BP)
- +/- Hyperlipidaemia
What are the complications of Nephrotic Syndrome?
- Infection-pneumonia
* Thrombosis (in nephrotic syndrome antithrombin III filtered out- lost mechanism to stop forming clots)
What are the common causes of Nephrotic Syndrome in adults?
- Membranous nephropathy (commonest); idiopathic primary glomerular disorder, usu. adults <60 yrs; M>F (20-30% progress to end stage renal failure)
- Focal segmental glomerulosclerosis (FSGS); various possible causes (usu. idiopathic, but also genetic, heroin use, HIV); M>F
- Minimal change disease; normal histology; M=F
- Other causes: diabetes, lupus nephritis, amyloid
What are the common causes of Nephrotic Syndrome In children?
• Minimal change (commonest)- present with nephrotic syndrome triad; normal histology, usu. Excellent prognosis, give them steroids & they’ll be fine
• Focal segmental glomerulosis (FSGS)
• Other causes rare
Basement memb thickening, get holes punched through=progresses to end stage renal failure
What is Nephritic Syndrome?
Kidney disease involving inflammation
What are the features of Nephritic Syndrome?
- Oedema
- HAEMATURIA
- Proteinuria
- Hypertension
- Acute renal failure
- (Lots of overly with nephrotic syndrome)
What are the common causes of Nephritic Syndrome in adults?
- Post-infective glomerulonephritis (happens after a primary infec)- weeks after Streptococcal throat infection, good recovery- then develop renal failure
- IgA nephropathy (inappropriate IgA deposition in glomerulus)- common primary glomerular disease; usu. young adults (20-50% renal failure over 20 years)
- Vasculitis; unwell, fever, rash, myalgia, arthralgia- spectrum of malaise with rash & renal failure
- SLE (lupus nephritis); autoimmune disease; usu. young women, get full spectrum of immunoglobulins involved
What are the common causes of Nephritic Syndrome In children?
• Also post-infective glomerulonephritis & IgA nephropathy
• Henoch-Schönlein purpura;
o Specific IgA nephropathy (systemic vasculitis); often follows throat infection; most recover completely
o Usu. boys/teenagers with arthralgia, abdominal pain, purpuric rash (presentation- affects buttocks & legs- most kids recover from this), proteinuria/haematuria, acute renal failure
• Haemolytic-uraemic syndrome
o Typically children with E. coli 0157 enteritis- due to shegoli toxin made (damages glomeulus endothelium= becomes pro-thrmbotic= lumen narrowed = RBCs break open as trying to squeeze past & are depleting your platelets)
• With other GI toxins
• Get GI symptoms 1st e.g. diarrhoea then renal failure
• Acute nephritis, haemolysis, thrombocytopenia
What is the main difference between Nephrotic syndrome and nephritic syndrome?
Nephrotic syndrome loss of protein, nephritic syndrome loss of blood
What is Acute Renal Failure ?
Rapid loss of kidney function
- Prognosis usually good if no underlying renal disease
- Short term dialysis may be needed in some patients
- Renal biopsy; UNHELPFUL if cause pre-renal or post-renal, HELPFUL if cause damage to kidney (renal)
- Imaging helpful- see obstruc
- All biopsies show acute tubular necrosis/injury/damage
What are the common causes of Acute Renal Failure ?
o Pre-renal (blood flow to kidney); severe dehydration, hypotension (bleed, septic shock, LVF), vol not reaching kidneys (oliguria) o Renal (in kidney); damage to kidney o Post-renal (probs getting rid of urine- urinary tract obstruc); urinary tract tumours, pelvic tumour, calculi, prostatic enlargement
What are the features of Acute Renal Failure?
Anuria/oliguria (<400ml/24h)+(rapid increase) raised creatinine & urea– malaise, fatigue, nausea, vomiting, arrhythmias
What are the common causes of Acute Renal Failure in adults?
o Vasculitis
o Acute interstitial nephritis/tubulointerstitial nephritis (tubular damage with inflammation, usu. due to drugs); most recover
What are the common causes of Acute Renal Failure in children?
o Henoch-Schönlein purpura
o Haemolytic uraemic syndrome (from e.coli infec)
o Acute interstitial nephritis
• Beware (in books): rapidly progressive (crescentic) glomerulonephritis = acute nephritis with acute renal failure but is NOT a specific disease.
What are the complications of Acute Renal Failure?
o Cardiac failure (fluid overload) o Arrhythmias (electrolyte imbalance)- sodium & K+ management o GI bleeding (multifactorial) o Jaundice (hepatic venous congestion) o Infection, esp. lung and urinary tract
What is treatment of Acute Renal Failure?
o Depends on underlying cause! E.g. hypovolemic give fluids, obstruction- remove obstruc
o Short term dialysis may be needed
What is Chronic Renal Failure ?
loss of kidney function over time
Renal biopsy usu. unhelpful in established disease; kidney shows severe scarring with loss of glomeruli & tubules (doesn’t matter what original cause was), end-stage renal disease due to any cause is similar
What are the stages Chronic Renal Failure ?
• Permanently reduced GFR= reduced no. functional nephrons
o Stage 1: Normal/increased GFR (>90ml/min/1.73m2)
o Stage 2: Mild GFR reduc (60-89ml/min/1.73m2)
o Stage 3: Moderate GFR reduction (30-59ml/min/1.73m2)
o Stage 4: Severe GFR reduction (15-29ml/min/1.73m2)- need renal replacement theapy (dialysis/ transplant)
o Stage 5: Kidney failure (GFR <15ml/min/1.73m2 or dialysis)
What are the features of Chronic Renal Failure?
o Reduced excretion of water/electrolytes: oedema, hypertension
o Reduced excretion of toxic metabolites
o Reduced production of erythropoietin: anaemia
o Renal bone disease (kidneys excrete phosphate/calcium), kidney’s involved in vit D metabolism- active vit D3 promotes Ca reabsorption)- chronic disorder
loads of symptoms-systemic
What are the consequences of Chronic Renal Failure?
o In utero;
o Amniotic fluid in uterus is contributed by urine from foetus- so if foetus doesn’t have any kidney’s/ prob with kidneys then not enough aminotic fluid and lungs need amniotic fluid to develop so lungs will be affected
o If kidneys have posterior urethral valves stops urine being excreted =kidney damage & lung development affected
What is Isolated Proteinuria? What are the causes?
• Proteinuria BUT less than nephrotic range
• No allied haematuria, renal failure or oedema
• May be benign e.g. postural, related to pyrexia or exercise (change heamodynamic flow & cause temporary proteinuria)
• May be due to renal disease (need to be able to exclude these)
o Adults: FSGS, DM, SLE
o Children: FSGS, HSP
• Urine samples tend to be frothy- protein in urine creates bubbles
What is Isolated Haematuria? What are the causes?
• Haematuria +/- proteinuria with normal renal function: usu. renal
o IgA nephropathy
o Thin basement membrane disease: inherited condition causing abnormally thin glomerular BM; renal function usu. normal
o Alport hereditary nephropathy: inherited abnormalities of type IV collagen cause abnormal BM, sometimes with eye and ear problems - renal failure +/- deafness +/- ocular problems (as basement memb struc also involved in ear & eye)
• Cystoscopy/urological investigations needed to exclude malignancy (nephroscopy, CT KUB)
What is Pyelonephritis?
- Kidney inflammation as a result of bacterial damage
* Infec; haematogenous spread, or ascends form urinary tract tracking back up into kidneys, structural abnormalities
What are the risk factors of Acute pyelonephritis?
o Risk factors; female (ascending infec), instrumentation, diabetes, urinary tract structural abnormalities
What are the complications of Acute pyelonephritis?
abscess formation
What are the risk factors of Chronic pyelonephritis?
Risk factors; urinary tract obstruc/ reflux
What are the complications of Chronic pyelonephritis?
scarring (=loss of functional renal tissue ), chronic renal failure
What is Renal Artery Stenosis? What are the causes? What are the complications?
- Commonly due to atheroma (lumen narrowing in 1/ both renal arteries- downstream damage); also arterial dysplasia
- Ischaemic injury of affected kidney
- Renin-angiotensin-aldosterone system activation=HTN (hypertension- damages kidneys further)
- Loss of renal tissue leads to reduced renal function
- Inflammatory damage- proliferation in vascular wall
What is Vasculitis? What are the causes? What are the complications?
- Various types affecting diff calibre vessels
- Inflamm in glomerular vessels can cause clotting + obliteration of capillary lumena & glomerulus destruction
- Inflammation of larger renal arterioles can cause tubule hypoxia
- Often part of systemic disease – rash, myalgia, arthralgia, fever, weight loss (key diagnosis- not presented alone, has other symptoms)
What is Hypertension? What are the renal consequences?
- Damages renal vessels - wall thickening + reduction in lumen size
- This produces chronic hypoxia - loss of renal tubules + reduced renal function
- Reduced renal blood flow activates renin-angiotensin-aldosterone system- exacerbates HTN
What is Diabetes? What are the renal consequences?
• Commonest cause of end-stage renal failure in developed world
• Hyperglycaemia causes 2 mechanisms of damage:
o Damaged basement memb thickens & glomerulus makes excess extracellular matrix (nodules)
o Small vessel damage causes ischaemia and tubular damage
What is Myeloma? What are the renal consequences?
- Malignant tumour of plasma cells in bone marrow- causes abnormal proteins & antibodies to deposit in kidneys- cause obstruc
- Plasma cell tumour; excess Ig’s deposit in tubules cause inflamm & fibrosis
- Renal tubule loss causes irreversible decline in renal function
- Elderly patient with acute renal failure; exclude drug reactions
What is Obstructive Uropathy?
- Obstruction of urinary tract
- Obstruction can occur anywhere in urinary tract from renal pelvis to urethral meatus
- Onset may be chronic or acute
- Unilateral or bilateral
What are Causes of Urinary Tract Obstruction?
- Pelvis: calculi (get severe pain that comes & goes), tumors, uteropelvic stricture
- Ureter intrinsic: calculi, tumors, clots, sloughed papilla (in diabetes papilla tips get necrosis & sloughed away), inflammation
- Ureter extrinsic: pregnancy, tumours e.g. cervix, retroperitoneal fibrosis
- Bladder: calculi, tumour, functional (neurogenic)
- Prostate: hyperplasia, carcinoma, prostatitis (only in males
- Urethra: posterior urethral valves stricture, tumours (rare)
What is a Stricture?
muscle wall thin so urine can’t flow down, proximal urethra distended
What can cause Obstruction within the lumen of the Urinary Tract ?
- Urinary calculi
- Strictures (post-procedure, post-infective, congenital)
- Neoplasia
What can cause Abnormalities of the wall of the Urinary Tract?
- Neoplasia (benign or malignant)
* Congenital anatomical abnormalities
What can cause External Compression of the Urinary Tract?
- Tumour outside urinary tract
- Inflammatory conditions e.g. retroperitonaeal fibrosis (idiopathic) both ureters obstructed by fibrosis (need surgical/ chemotherapy to release ureters)
- Pregnancy
What can cause Functional Obstruction of the Urinary Tract?
• Neurological conditions
• Severe reflux
Bladder; functional stasis-
Urethra; abnormal valves in urethra, dysfunctional valve- urine tracts back up (reflux
What is Sequelae of Obstruction of the Urinary Tract?
- Urinary infec- cystitis, ureteritis, pyelitis, ascending pyelonephritis
- Stone/calculi formation
- Kidney damage (acute or chronic)
Consequences of Urinary Tract Obstruction Depend on; • Site of obstruction • Degree of obstruction • Duration of obstruction
What is Detrusor hypertrophy & trabeculation?
obstruction at urethral level
• Hypertrophy of muscle of bladder as obstruc in ureter
What is Hydroureter ?
Chronic Uretic Obstruction can= Hydroureter
• Stones consequence of obstruc
• Dye in kidney not going completely down
What is Hydronephrosis?
Hydronephrosis- a result of chronic obstruction
• Non-functional kidney- chronic infec/ obstruc
• Need to remove obstruc
• If fills with pus- high mortality
What is acute complete obstruction?
Decreased glomerular filtration rate can = acute renal failure
mild dilation and mild cortical atrophy
What is chronic complete obstruction?
Partial/intermittent obstruction=
• Continued glomerular filtration=dilation of pelvis and calyces=
• Filtrate passes back into interstitium= compression of medulla=impaired concentrating ability=
Both eventually = cortical atrophy, fall in renal filtration and renal failure.
What are Clinical Features of Acute bilateral obstruction?
- Pain
* Acute renal failure & anuria
What are Clinical Features of Chronic unilateral obstruction?
- Suspect obstruct- recurrent UTIs
- Asymptomatic initially
- If unresolved cortical atrophy and reduced renal function
What are Renal Calculi/ Urotheliasis?
- Affect 7-10% of the population - increasing
- Male predominance
- Peak onset 20 – 30
- Can form anywhere in urinary tract but most commonly in kidney