Glomerulonephritis & Polycystic Kidneys Flashcards
What is glomerular disease?
A general term for a group of diseases which affect the glomeruli of the kidneys
It is a common cause of CKD + ESRD
Which 2 conditions are termed under “glomerular disease”?
- Glomerulonephritis: inflammation of the glomeruli
- Glomerulopathies: immune complex/complement deposition without inflammation
**Overlap exists of these 2 conditions in real life
How is glomerular disease staged?
- Based on the signs + symptoms –> glomerular syndromes
- Specific blood tests + urine tests –> primary (idiopathic) or secondary (due to specific cause) glomerulopathy
- Ultrasound kidneys
- Renal biopsy –> type of glomerular pathology
- Minimal change
- FSGS (focus segmental glomerular sclerosis)
- Membranous
* * Based on light/electron microscopy, immunohistochemistry
What are the 3 main types of glomerular pathology?
- Minimal change
- FSGS (focus segmental glomerular sclerosis)
- Membranous
Name 3 systems you would think of which can present with symptoms of fluid overload.
- Heart failure
- Liver failure
- Kidney failure
What is peri-orbital oedema and when does it commonly present?
Swelling of the eyelids (puffy eyelids)
Seen in children with glomerulonephritis
What two bed side tests should the GP do next if after their examination they feel it might be a renal problem. What are they looking for and why?
- Urine Dipstick Test:
In glomerular diseases – blood and /or protein in the urine. - Blood Pressure:
Renal diseases result in inappropriate retention of salt and water, leading to hypertension.
The GP, Dr Paul finds Mr Smith, oedematous up to his thighs, but normotensive and urine dipstick showed 3+ protein.
What would his primary suspicion for this patient be?
A glomerular disease
What is the normal range for specific gravity?
Around 1.010
What are 3 causes of a low specific gravity?
Specific gravity = 1.00
- Excessive hydration
- Diabetes insipidus (deficiency/resistance to ADH)
- Acute tubular necrosis
What are 7 causes of a high specific gravity (1.035)
- Dehydration
- SIADH
- CHF
- Cirrhosis
- Glycosuria
- Proteinuria
- IV contrast recently
If regardless of hydration status the specific gravity remains 1.010, what does this indicate?
Advanced kidney failure
- Kidneys lose the ability to regulate urine concentration
What is pH from urinalysis useful for diagnosing?
- Renal tubular acidosis
- Monitoring urine alkalization to prevent precipitation of myoglobin in rhabdomyolysis
- Aid the elimination of certain drugs (aspirin, methotrexate)
- Differentiation of different types of kidney stones
What does a low pH indicate on urinalysis?
Acidemia
What does a high pH indicate on urinalysis?
Alkalemia
- Distal renal tubular acidosis
- UTI secondary to urease-producing organisms (proteus, klebsiella)
What does glucose in the urine indicate?
- Hyperglycemia (glycosuria -> osmotic diuresis -> dehydration)
- Proximal tubule dysfunction (i.e. Fanconi syndrome)
What are 3 broad possible causes of blood (heme) in the urine?
- Hematuria of any cause (UTI, renal stone, GU malignancy, nephritic syndrome)
- Rhabdomyolysis
- Contamination with semen
What are 3 causes of protein in the urine?
- Glomerular disease (diabetic nephropathy)
- Overflow proteinuria (multiple myeloma, rhabdomyolysis, intravascular hemolysis)
- Post-renal proteinuria (UTI)
In what 4 conditions would you see high leukocytes with normal nitrites?
- Urological malignancy
- Chronic interstitial nephritis
- Interstitial cystitis
- Intra-abdominal inflammatory process adjacent to the GU tract
In what conditions are ketones detected in the urine?
- Ketoacidosis
- Diabetes
- Alcoholic
- Starvation - Ketogenic diet
- Kids with epilepsy
Name 3 conditions when bilirubin/urobilinogen are present in the urine?
- Hemolysis
- Elevated urobilinogen - Biliary obstruction
- Elevated bilirubin
- Normal/decreased urobilinogen - Liver disease
- Variable bilirubin/urobilinogen
What is the normal excretion amount of protein in urine?
< 150mg
- Albumin < 30mg
What is the gold standard for checking protein levels in the urine?
24h urine collection
For convenience: urine ACR, PCR
What test is important in the diagnosis of early diabetic nephropathy (reversible glomerular damage)?
Urine ACR
- Albuminuria > 300mg/24h is detected on urine dipstick
- UPCR in gms/24h is used to monitor this
What is glomerular filtration?
- Process by which cells + large proteins are removed from the blood to create ultra filtrate
- Occurs in the renal corpuscle
- Is driven by opposing pressures exerted by the contents of the blood + ultrafiltrate
How does glomerulonephritis affect glomerular filtration?
Inflammation of the filtration membrane alters its permeability and inhibits proper filtration
What is the difference between hydrostatic + oncotic pressures?
Hydrostatic = push out
- Forces that blood + ultrafiltrate exert on filtration membrane
Oncotic = suck in
- Forces that proteins within the blood + ultrafiltrate exert to draw water towards them
What is the pathophysiology of glomerulonephritis?
Unknown but thought to be:
- Due to immunological response to a variety of aeitological agents
- Group A strep
- Viral infections: hepatitis C
- Some drugs
Immunological Response:
A) Immunoglobulin and complement activation within the glomeruli (where the antigen is a structural component of the glomeruli e.g. Good Pastures antigen in the glomerular basement membrane)
B) The antigens may be trapped or deposited within the glomeruli
C) Trapping of circulating immune complexes (less common in human GN)
When abnormalities occur in the glomerulus patients what clinical syndromes can they present with?
- Isolated haematuria /proteinuria OR haematoproteinuria
- Nephrotic Syndrome (inflammation)
- Acute glomerulonephritis ( acute nephritic syndrome )
- Rapidly progressive glomerulonephritis (RPGN )
- Chronic Kidney Disease including ESRD
What is nephrotic syndrome?
Loss of protein because podocytes/basement membrane aren’t working properly (endothelial cells)
What are symptoms of nephrotic syndrome?
- Loss of 3.5g/day of protein
- Frothy urine
- Low albumin
- High lipids (serum + urine)
- Low AT-III (antithrombin 3) = hypercoagulable state = thrombosis in renal vein = DVT/PE
What is nephritic syndrome?
Immune complexes lodged in capillaries illicit immune response against capillaries + antigens
- White cells are recruited = inflammation!
- RBCs + WBCs + proteins can get thru epithelial cells
(nephrotic range proteinuria as a result of nephritic syndrome)
What are the symptoms of nephritic syndrome?
- Hematuria + sediment in urine
- WBCs in urine
- Oliguria (glomerulus is damaged = low GFR)
- Hypertension (b/c of lack of filtration)
- Granular casts
What are the 4 stages of nephrotic syndrome?
- Minimal Change
- Normal light microscopy / electron microscopy effacement of podocytes
- Commonest cause in children - Focal Segmental Glomerulosclerosis (FSGS)
- Scarring in glomerulus – with only some glomeruli affected (focal) and only parts of individual glomerulus affected (segmental)
- Common cause in adults - Membranous Glomerulonephritis
- Immune deposits on basement membrane and a second membrane forms over these deposits with irregular spikes where several immune complexes deposited - Membranoproliferative Glomerulonephritis
- Similar to membranous but immune deposits also present in mesangium, not just basement membrane
What are 5 secondary causes of nephrotic syndrome?
- Autoimmune (e.g. SLE)
- Infections (e..g. malaria, hepatitis B & C, HIV)
- Drugs (e.g. NSAIDs, pencilliamine)
- Heavy metals (e.g. gold, mercury)
- Tumours (solid tumours e.g. lung, colon and haematological malignancies e.g. multiple myeloma)
How can diabetes affect the kidneys?
Diabetic nephropathy
In late stages = nephrotic syndrome
Renal biopsy must be avoided. If done will see nodules in the mesangium known as Kimmelstiel-Wilson lesions