NEPHROLOGY Flashcards
Adrenal cortex (mnemonic GFR - ACD)
- Zona Glomerulosa (on outside): mineralocorticoids, mainly Aldosterone
- Zona Fasciculata (middle): glucocorticoids, mainly Cortisol
- Zona Reticularis (on inside): androgens, mainly Dehydroepiandrosterone (DHEA)
Renin
- Released by JGA cells in kidney in response to ↓ renal perfusion, low sodium
- Hydrolyses angiotensinogen to form angiotensin I
Factors stimulating renin secretion
- ↓ BP → ↓ renal prefusion
- Hyponatremia
- Sympathetic nerve stimulation
- Catecholamines
- Erect posture
Factors reducing renin secretion
β-blockers
NSAIDS
Angiotensin
- ACE in lung converts angiotensin I → angiotensin II
- Vasoconstriction leads to raised BP
- Stimulates thirst
- Stimulates aldosterone and ADH release
Aldosterone
Released by the zona glomerulosa in response to raised angiotensin II, potassium, and ACTH levels
Causes retention of Na+ in exchange for K+/H+ in distal tubule
Anemia in CRF:
Correction o iron with IV if needed
* Ferritin should be > 200 ng/mL before starting EPO
* EPO is used to target Hb 10-12 (>11 or hematocrit >33%) reach the target within 4 months
* Corrected Hb of > 13.5 is associate with HTN crisis
* Hb < 10.5 ↑ risk of seizures.
Erythropoietin:
(EPO) is a hematopoietic growth factor that stimulates the production of erythrocytes. The main uses of erythropoietin are to treat the anemia associated with chronic renal failure and that associated with cytotoxic therapy
Side-effects of erythropoietin
HTN and HTN crisis, potentially → encephalopathy and seizures (BP ↑ in 25% of patients)
* EPO induced seizures occurs after 90 days fro starting the treatment
* Bone aches
* Flu-like symptoms
* Skin rashes, urticaria
* Pure red cell aplasia* (due to antibodies against erythropoietin)
* Raised packed cell volume (PCV) =HCT → ↑ risk of thrombosis (e.g. Fistula)
* Iron deficiency 2nd to ↑ erythropoiesis
There are a number of reasons why patients may fail to respond to erythropoietin therapy
Iron deficiency
* Inadequate dose
* Concurrent infection/inflammation
* Hyperparathyroid bone disease
* Aluminum toxicity
Indication for Urgent Dialysis:
- Severe acidosis
- Pulmonary edema due to volume overload
- Hyperkalemia
- Uremic pericarditis
- Severe uremic symptoms
Hyperacute graft rejection is due
pre-existent antibodies to HLA antigens and is therefore IgG
mediated
Graft survival
time frames
1 year = 90%, 10 years = 60% for cadaveric transplants
* 1 year = 95%, 10 years = 70% for living-donor transplants
Renal Transplant: Post-op problems (can cause graft dysfunction) – up to 4 months post-op:
Acute rejection: risk is great in 1st 2 weeks occurs in 30-50% of cases
* Ciclosporin toxicity
* A TN of graft
* V ascular thrombosis
* Urine leakage
* UTI
Hyperacute graft rejection
- Due to antibodies against donor HLA type 1 antigens
- Rarely seen due to HLA matching
Management of acute graft failure (< 6 months) - Acute rejection: give steroids, if resistant use monoclonal antibodies
Causes of chronic graft failure (> 6 months)
Chronic allograft nephropathy
* Ureteric obstruction
* Recurrence of original renal disease (MCGN > IgA > FSGS)
Hyperacute graft rejection is due to pre-existent antibodies to HLA antigens and is therefore IgG
mediated
Autosomal Dominant Polycystic Kidney Disease:
(ADPKD) is the most common inherited cause of kidney disease, affecting 1 in 1,000 Caucasians. Two disease loci have been identified, PKD1 and PKD2, which code for polycystin-1 and polycystin-2 respectively
ADPKD - Ultrasound diagnostic criteria
In < 20 yrs age, CT scan is not needed
* In < 20 yrs age, ultrasound gives false –ve
* 2 cysts, unilateral or bilateral, if aged < 30 years
* 2 cysts in both kidneys if aged 30-59 years
* 4 cysts in both kidneys if aged > 60 years
ADPKD Associtaed conditions:
Colonic diverticula (with any related symptoms, screen by barium enema)
* Mitral Valve Prolapse (needs echo screening)
ADPKD Management:
- Painkillers
- Urinary tract infections: → ABX
- ↑BP control
- End-stage renal disease → Transplantation
Autosomal Recessive Polycystic Kidney Disease (ARPKD)
much less common than autosomal dominant disease (ADPKD). It is due to a defect in a gene located on chromosome 6
Diagnosis may be made on prenatal ultrasound or in early infancy with abdominal masses and renal failure. End-stage renal failure develops in childhood. Patients also typically have liver involvement, for example portal and interlobular fibrosis
Nephrotic Syndrome:
Triad of
- Proteinuria (> 3g/24hr) causing
- Hypoalbuminemia (< 30g/L) and
- Edema
Nephrotic Syndrome path
Loss of antithrombin-III (↑↑↑), proteins C and S and associated rise in fibrinogen levels
predispose to thrombosis. Loss of TBG lowers total, but not free thyroxin levels
Nephrotic Syndrome Causes
- Glomerulonephritis (GN, c. 80%)
* Minimal change GN (causes 75% in children, 25% in adults)
* Membranous GN
* Focal Segmental GlomeruloSclerosis - Systemic disease (c. 20%) * Amyloidosis
* SLE - Drugs
* Gold (sodium aurothiomalate), penicillamine - Others
* Congenital
* Neoplasia: carcinoma, lymphoma, leukemia, myeloma
* Infection: bacterial endocarditis, hepatitis B, malaria
* Renal vein thrombosis
Complications Nephrotic Syndrome
↑ risk of infection due to urinary immunoglobulin loss
* ↑ risk of thromboembolism related to loss of antithrombin III and plasminogen in the urine
* Hyperlipidemia
* Hypocalcemia (vitamin D and binding protein lost in urine)
* Acute renal failure could be due to thrombotic renal veins it comes with lion pain and
hematuria.
Membranous glomerulonephritis
Presentation
Cause
Presentation: proteinuria / nephrotic syndrome / CRF
* Cause: infections, rheumatoid drugs, malignancy
* 1/3 resolve, 1/3 respond to cytotoxics, 1/3 develop CRF
IgA nephropathy - AKA Berger’s disease, mesangioproliferative GN
- Typically young adult with hematuria following an URTI
- Associated with Henoch-Schonlein purpura
- Mesangial hypercellularity (mesangioproliferative)
. Diffuse proliferative glomerulonephritis
Classical post-streptococcal glomerulonephritis in child
* Presents as nephritic syndrome / ARF
* Most common form of renal disease in SLE (IV)
Minimal change disease
Typically a child with nephrotic syndrome (accounts for 80%)
* Causes: Hodgkin’s, NSAIDs
* Good response to steroids
Focal segmental glomerulosclerosis
May be idiopathic or secondary to HIV, heroin
* Presentation: proteinuria / nephrotic syndrome / CRF
Rapidly progressive glomerulonephritis (RPGN) - AKA Crescentic Glomerulonephritis
Rapid onset, often presenting as ARF
* Causes include Goodpasture’s, ANCA positive vasculitis (e.g. Wegener’s granulomatosis)
. Mesangiocapillary glomerulonephritis (membranoproliferative)
Type 1: cryoglobulinemia, hepatitis C → associated with low C4
* Type 2: partial lipodystrophy → associated with low C3
Disorders associated with glomerulonephritis and low serum C3 levels:
Post-streptococcal glomerulonephritis
* Subacute bacterial endocarditis
* Systemic lupus erythematosus
* Mesangiocapillary glomerulonephritis
Membranous glomerulonephritis renal biopsy
Renal biopsy demonstrates:
* Sub-epithelial immune complex (mainly IgG and C3) deposition in the glomerulus
* Electron microscopy: the basement membrane is thickened with sub-epithelial electron dense
deposits (IgG, C3)
Membranous glomerulonephritis Causes
Idiopathic
* Infections: hepatitis B, malaria
* Malignancy: lung cancer, lymphoma, leukemia
* Drugs: gold, penicillamine, NSAIDs
* SLE (class V disease)
Membranous glomerulonephritis Management
Immunosuppressant: steroids, cyclophosphamide, chlorambucil e.g. Ponticelli regime
* BP control
* Consider anticoagulation
IgA Nephropathy: Basics
Also called Berger’s disease or mesangioproliferative glomerulonephritis
* Commonest cause of glomerulonephritis worldwide
* Pathogenesis unknown, ?Mesangial deposition of IgA immune complexes
* Histology: mesangial hypercellularity, positive immunofluorescence for IgA & C3
Differentiating between IgA nephropathy and post-streptococcal (diffuse proliferative) glomerulonephritis:
- Post-streptococcal glomerulonephritis is associated with low complement levels
- Main symptom in post-streptococcal glomerulonephritis is proteinuria (although hematuria can
occur) - There is typically an interval between URTI and the onset of renal problems in post-
streptococcal glomerulonephritis
IgA Nephropathy:Presentations
Young ♂, recurrent episodes of Hematuria, usually painless (sometimes with no renal impairment)
* Typically associated with mucosal infections e.g., URTI
* Nephrotic range proteinuria is rare
* Renal failure
IgA Nephropathy Associated conditions
Alcoholic cirrhosis
* Celiac disease/dermatitis herpetiformis
IgA Nephropathy Prognosis
25% of patients develop ESRF
* Markers of good prognosis: frank hematuria
* Markers of poor prognosis: ♂ gender, proteinuria (especially > 2 g/day), hypertension,
smoking, hyperlipidemia, ACE genotype DD
Minimal Change Glomerulonephritis presentation
Nearly always presents as nephrotic syndrome, accounting for 75% of cases in children and 25% in adults
Minimal Change Glomerulonephritis treatments
prednisolone
ACE inhibitors may be used to ↓ proteinuria in patients with heavy proteinuria or who have a slow response to prednisolone
Minimal Change causes
Causes: majority of cases are idiopathic, but in around 10-20% a cause is found:
* Drugs: NSAIDs, rifampicin
* Hodgkin’s lymphoma, NHL and thymoma
* Infectious mononucleosis