Renal/urinary Conditions, Signs, Causes And Differentials Flashcards
What are the three processes that cause renovascular disease?
- Renal artery stenosis (atherosclerosis causing narrowing of the arteries)
- Renal vein thrombosis (blockage)
- Renal atheroembolism (blockage)
What are the renal conditions that cause secondary hypertension?
Primary renal disease (kidney parenchyma dysfunction):
- Glomerulosclerosis,
- Membranous nephropathy
- Amyloidosis
- Glomerulonephritis (glomerular inflammation)
- Chronic kidney disease (decrease in GFR)
- Polycystic kidney disease
Renovascular disease (blood supply is occluded or reduced)
- Artery stenosis
- Vein thrombosis
- Atheroembolism
Which test result would point towards a renal cause of hypertension?
Increased creatinine
Due to either:
Renal parenchyma not filtering properly (expect progressive increase in creatinine)
Renal blood supply/drainage occlusion (expect an acute increase in creatinine)
What are the differentials for proteinuria?
Benign orthostatic proteinuria Physical exercise Fever Pregnancy UTI Abnormally high BP Nephrotic syndrome (damage to the kidneys) Nephritic syndrome (inflammation of the kidneys)
Through which pathophysiological process does CKD in diabetes progress?
Hypertension - high BP causes damage to the glomerulus via haemodynamic mechanisms.
This is why the single most important intervention for CKD is good blood pressure control.
What is diabetic nephropathy?
Disease of the kidney caused by diabetes
Since diabetes causes autonomic disfunction and damage to the blood vessels, this increases the likelihood of hypertension, as well as hyperglycaemia inducing the conversion of angiotensin 1 to 2, which also increases BP.
What are the four stages of diabetic nephropathy?
Basically: thicken at circumference, then thicken in centre, then nodules grow around centre, then nodules are diffuse and widespread
- Glomerular basement thickening (outer)
- Mesangial expansion (central)
- Nodular sclerosis (kimmelstiel-Wilson lesions; pink hyaline material in the capillary loops)
- More than 50% glomerulosclerosis; not nodular anymore but diffuse
What are the pathological processes within the kidney that cause diabetic nephropathy?
In short: Hypertension and hyperglycaemia cause high pressure in the glomerulus, this damages the mesangium, and the nephron dies.
- Increased glomerular pressure due to:
A - Hypertension in the body forces blood in to the glomerulus harder, increasing the glomerular pressure
B - Hyperglycaemia which causes the conversion of angiotensin 1 to angiotensin 2, activating the RAAS system
- The increased glomerular pressure, over time, causes barotrauma of the mesangium:
A - cytokines release causing inflammation
B - free radical formation
C - mesangial expansion
These processes cause podocyte foot processes to move apart, causing increase in fenestration size - Nephron ischemia:
A - Excess efferent arteriolar constriction reducing the supply to the vasa recta which supply the entire nephron (capsule to collecting duct)
B - Free radicals and cytokines causing increased stress on the nephron
These processes increase the rate of atrophy and destruction of the nephron
What is the progression of clinical findings in diabetic nephropathy?
- Increased GFR = early increased perfusion due to increased BP and RAAS activation
- Detectable proteinuria and microalbuminaemia = the start of barotrauma to the nephron due to dangerously high glomerular pressure
- Microhaematuria = the damage to the glomerulus is so bad, red blood cells (big) can get through the glomerulus and in to the tubule
- Kidney failure and decreased urine output = the nephrons are now starting to die and can’t filter anything
What is chronic kidney disease?
In short: Either structural abnormality/abnormal blood/urine results for >3 months or GFR <60 for 3 months, on TWO separate occasions 90 days apart.
A progressive, irreversible, chronic condition of damage to the kidney or reduced kidney function, defined by:
1. A)Evidence of damaged renal parenchyma as demonstrated by active urinary sediment (proteinuria or haematuria)
- B)and/or structural abnormality
- C)and/or evidence of decreased kidney function as demonstrated by a reduced GFR <60
- Plus CHRONICITY for >3 months (or it isn’t distinguished from AKI)
What are the symptoms of CKD?
Normally asymptomatic
Only in advanced disease do you acquire symptoms:
How do the causes of CKD differ between old people and younger people?
Most people are elderly - CKD due to HTN/Macrovascular disease/DM
Young people - CKD more often due to glomerulonephritis and genetic causes
What is rapidly progressing renal failure?
Renal disease that progresses fast, over a matter of weeks or months.
Most often due to vasculitis, sarcoidosis or another systemic disease that targets the kidneys.
What is end stage renal disease?
An individual who requires haemo replacement: dialysis or transplant
What is azotaemia?
Azotaemia is elevation of nitrogenous metabolic waste in the blood due to failure of clearance by the kidneys.
Azotaemia = uraemia but asymptomatic
What is uraemia?
Uraemia is the clinical syndrome from failing kidneys and progressive azotaemia
Uraemia = azotaemia + symptoms/signs
What are the causes of CKD?
DM - most common
HTN - second most common
Glomerulonephritis- 3rd most common (a group of conditions, including autoimmune and infection)
Autoimmune disease Systemic sepsis UTI Renal stones Urinary obstruction Drug toxicity - NSAIDs
What are the symptoms of uraemia?
Nausea Vomiting Weakness and fatigue Pruritis Neurological symptoms Weight loss Uraemic pericarditis
Uraemia is unlikely to occur in patients since by the time they get close to uraemia (kidney failure) they will be dialysed.
Why does metabolic acidosis occur in renal failure?
The kidneys reduce their production and reabsorption of bicarbonate - reduced buffering.
Increased protein catabolism occurs and this produces lots of organic acids - increased acidity.
What kind of unusual infections do renal transplant patients have?
Since they are immunosuppressed in order to prevent rejection, infections like:
Cytomegalovirus colitis (long history of diarrhoea)
Pneumocystitis jirovecii pneumonia (long history of cough or crackles on chest)
Perforated diverticulitis
Cholecystitis
Pancreatitis
What causes pruritis in CKD?
Phosphate homeostasis is disrupted in CKD, this is due to decreased renal excretion.
Hyperphosphataemia results, which causes the pruritis
What is glomerular disease?
A term to describe a group of diseases that affect the glomeruli of the kidney (common cause of ESRD and CKD)
It involves:
- Inflammation - glomerulonephritis
- Damage to the functional mechanism of the glomeruli without inflammation - glomerulopathies
In practise the two of these pathological processes can overlap in a glomerular disease.
How are glomerular diseases distinguished?
They all have similar sets of signs and symptoms, so are called glomerular syndromes.
They can only be distinguished by biopsy and histopathological classification.
Classification:
- Glomerular syndrome (or not)
- Glomerular pathology type
- Primary, idiopathic or secondary cause
What is glomerular nephritis?
A group of diseases in which there is damage to the glomeruli, this can be due to many different causes; viruses, bacteria, autoimmune, drugs and others.
Most are due to immune-responses to causal agents. Not all types of glomerulonephritis present with nephritic syndrome.
Presentation can be nephrotic syndrome, nephritic syndrome (acute glomerulonephritis or rapidly progressive glomerulonephritis), CKD, just haematuria or just proteinuria
MOA: Activation of the innate and adaptive immune systems due to;
- Kidney=antigen - Reacting to a component of the glomeruli (acting as antigen)
- Antigen=filtered - Deposition/trapping of antigens in the glomeruli
- Antigen/antibody=filtered - Trapping of circulating immune complexes
What are the causes of glomerular nephritis?
Bacteria: Group A streptococci
Viruses: Hepatitis B/C, HIV, malaria, leprocy, endocarditis, other
Respiratory and GI infections
Drugs: NSAIDs, cocaine, anabolic steroids, penicillamine, heroin
Metabolic disorders: DM, HTN, thyroiditis
Malignancy: lung and colorectal, melanoma, Hodgkin’s lymphoma
Lots of others
How does glomerular nephritis present?
The presentation is variable:
- Just haematuria or proteinuria or both
- Reduced eGFR, and increased ACR - Chronic kidney disease
- Acute nephritic syndrome - Acute glomerulonephritis
- Rapidly progressive glomerulonephritis
- Nephrotic syndrome
What is nephritic syndrome?
In short: immune complexes damaging the capillary endothelium allow RBCs, WBCs, AND proteins (less than nephrotic syndrome) through the glomerular membrane
Nephritic syndrome is a collection of signs and symptoms that indicate damage to capillaries and basement membrane of the glomeruli
- Haematuria
- Sub-nephrotic syndrome proteinuria
- Hypertension
MOA: Immune complexes deposit in the capillaries, these draw WBCs with them which cause an inflammatory response causing inflammation and breakdown of the capillary endothelium, these make big fenestrations, allowing blood, protein and WBCs through in to the urine.
