Lecture 15 - Chronic Kidney Disease Flashcards
What % of the population has CKD?
10%
How do we assess the excretory function of the kidneys?
GFR
What classification system is used to stage CKD?
NKF K?DOQI Classification System
Stage 1 - Kidney damage/normal/high GFR >90
Stage 2 - kidney damage/mild reduction GFR 60-89
Stage 3 - moderately impaired, a - GFR 45-49, b - 30-44
Stage 4 - severely impaired - GFR 15-29
Stage 5 - advanced or on dialysis - GFR <15
What is the relationship between GFR and serum creatinine?
As GFR reduces, serum cr increases
What can serum creatinine depend on apart from kidney function?
Muscle mass (age, ethnicity, gender, wt)
What formulae can be used to estimate GFR?
Cockcroft Gault
Modification of diet renal disease equation
What 4 variables does the MDRD equation look at?
Serum cr
Age
Gender
Ethnicity
Which factors may affect someone eGFR?
Pregnancy
Muscle mass
Eating red meat 12h before the sample was taken
What substances are allowed to cross the GBM?
Water, electrolytes, urea, creatinine
What substances can cross the GBM but are reabsorbed in the PCT?
Glucose
Low molecular weight proteins
What substances cannot cross the GBM in health?
Cells
High molecular wt proteins
How can we assess kidney filtering function?
Should be no protein/urine in urine - urinalysis (check for blood + protein)
May want to do protein quantification (protein creatinine ratio)
How might we assess the anatomy of the kidney in CKD?
Histology
Radiology
What is the current CKD definition?
Presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR <60ml/min/1.73m2 that is present >=3m
Why is CKD important?
Can lead to kidney failure –> dialysis and transplant
Complications
CKD death
What are complications of CKD?
Acidosis Anaemia Bone disease CV complications Death, dialysis Electrolyte imbalances Fluid overload Gout HTN Iatrogenic issues
Complications of CKD are more likely with worsening….
GFR
What does increased mortality in CKD correlate with?
Worsening renal function
What are causes of CKD?
Diabetes Polycystic kidney disease Chronic pyelonephritis Renovascular disease (renal artery stenosis from atherosclerosis or fibromuscular dysplasia --> ischaemic nephropathy) HTN GNs Myeloma IgA nephropathy Sarcoidosis Chronic exposure to nephrotoxins Reflux nephropathy and scarring Chronic obstructive nephropathy (e.g. prostatic disease, mets, retroperitoneal fibrosis, PUJ obstruction)
What is the clinical approach to managing CKD?
Detect underlying aetiology + treat
Slow rate of renal decline
Assess complications/prevent complications
Prepare for RRT
What may be some presenting features of CKD?
Cognitive changes Fatigue Vomiting/nausea Change in urine output Haematuria/proteinuria (frothy urine/cola coloured urine) Peripheral oedema Itch and camps HTN SoB
What specific systemic diseases are good to ask about when taking a history of someone with CKD?
DM
Collagen vascular diseases, e.g. SLE, scleroderma, vasculitis
Malignancies - myeloma, breast, lung, lymphoma
HTN
Sickle cell disease
Amyloidosis
What drugs are good to ask about when taking a history from someone with CKD?
NSAIDs Penicillins/aminoglycosides Chemotherapeutic agents Narcotics ACEi/ARBs
What pre/post renal factors should you ask about in your history when you’re assessing someone with CKD?
CCF Diuretic use N/V/D Cirrhosis LUTS/pelvic disease
What uraemic symptoms might someone with CKD present with?
Nausea, anorexia, vomiting
Pruritus
Wt loss
Fatigue, weakness, drowsiness
What investigations might you do in CKD to detect the underlying aetiology?
Bloods - UE, FBC, bicarb, total protein, albumin, Ca, phosp, LFTs, CK
Coagulation screen
Urine - dipstick, PCR/ACR 24h collection
Histology - renal biopsy
Radiology
Re: investigations in CKD to exclude active disease
What is a serum and urine electrophoresis used to check for?
Myeloma
Re: investigations in CKD to exclude active disease
What is a urine protein: creatinine ratio used to check for?
Intrinsic renal disease
Re: investigations in CKD to exclude active disease
What is a CK used to check for?
Rhabdomyolysis
Re: investigations in CKD to exclude active disease
What is an anti-GBM used to check for?
Anti-GBM disease
Re: investigations in CKD to exclude active disease
What are ANCA, ELISA for MPO or PR3 used to check for?
ANCA associated vasculitides
Re: investigations in CKD to exclude active disease
What are C3, C4, autoantibody screen used to check for?
Connective tissue disease, SLE, MCGN, cyroglobulinaemia, infection related glomerulonephritis
What imaging might you need to use when trying to find the aetiology of CKD?
US
X-ray
CT
MRI
When might you biopsy someone’s kidneys in CKD?
Unexplained renal failure with normal sized kidneys
What things can be done to slow the rate of decline of CKD?
BP control Control proteinuria Reversible contributing factors Allopurinol Dietary protein restriction Fish oils Lipid lowering Control acidosis
What is associated with a faster decline in GFR?
High BP
What investigations would you do to assess for acidosis as a complication of CKD?
Bicarbonate, pH
What investigations would you do to assess for anaemia as a complication of CKD?
FBC, film, haematinics
What investigations would you do to assess for bone disease as a complication of CKD?
Ca, Phosp, albumin, PTH
What investigations would you do to assess for CV complications as a result of CKD?
BP, cholesterol
What investigations would you do to assess for electrolyte imbalance as a complication of CKD?
UE
What investigations would you do to assess for fluid overload as a complication of CKD?
Ex - BP, oedema, JVP
CXR
What investigations would you do to assess for gout as a complication of CKD?
Hx, Ex
What investigations would you do to assess for HTN as a complication of CKD?
BP
At what GFR is metabolic acidosis due to CKD usually seen?
<20mls/min
What electrolyte abnormality does metabolic acidosis worsen in CKD?
Hyperkalaemia
Also exacerbates bone disease
How is metabolic acidosis in CKD treated?
Oral Na bicarb
When does anaemia due to CKD usually manifest?
GFR <35mls/min
What kind of anaemia do you see in CKD?
Normochromic normocytic
What are the causes of anaemia in CKD?
Reduced EPO production (most important)
Reduced erythropoiesis due to toxic effects of uraemia on bone marrow
Reduced absorption of Fe
Anorexia/nausea due to uraemia
Reduced red cell survival (esp in haemodialysis)
Blood loss due to capillary fragility and poor platelet function
Stress ulceration –> chronic blood loss
When should you treat anaemia in CKD?
If <10g/dl or symptomatic
How is anaemia in CKD treated?
Iron replacement
ESA therapy
What electrolyte abnormality results from increased GFR?
Hyperphosphataemia
Why do you get bone disease in CKD?
Hyperphosphataemia + loss of renal tissue –> lack of activated vit D (as low Ca)
Secondary hyperparathyroidism
What must happen to vitamin D to turn it into its active form?
Must be hydroxylated
What enzyme catalyses the hydroxylation of vitamin D?
1a hydroxylase
Why do you get a vitamin D deficiency in CKD?
Low 1a hydroxylase levels so low activation of vitamin D
Why do you get secondary hyperparathyroidism in CKD?
Low ca and high phosphate stimulates parathyroids to produce more PTH to try and correct the imbalance
What cardiovascular complication is hyperphosphataemia associated with?
Vascular and cardiac calcification
Why are those with CKD at increased risk of fractures?
Increased PTH –> increased bone turn over
How is renal bone disease managed?
Control phosphate (limit in diet) Phosphate binders (e.g. CaCO3, Ca acetate...) Normalise Ca and PTH (active vit D analogues (calcitriol)
If teritary hyperparathyroidism develops - parathyroidectomy + calcimetics
What CV complications are associated with CKD?
HTN
Hyperlipidaemia
Uraemic pericarditis
What K level may induce a fatal cardiac arrhythmia?
> 7mmol/l
What is involved in the management of chronic hyperkalaemia?
Diet
Drug modifications
What does fluid overload lead to?
HTN
Oedema
How is fluid overload in CKD managed?
Na restriction
Fluid restriction
Loop diuretics
What should be the goal BP in CKD?
<125/75 in CKD with significant proteinuria or 130/80 if no proteinuria
What drug can be used to treat HTN in CKD?
ACEi may offer additional advantage
Which drugs commonly cause AKI on top of CKD?
Antibiotics
Contrast agents
How can you manage CV complications of CKD?
BP control, aspirin, cholesterol reduction, exercise, wt loss
What drugs should be avoided in renal failure?
Antibiotics - tetracycline, nitrofuratoin
NSAIDs
Lithium
Metformin
What drugs are likely to accumulate in CKD and may require dose adjustment?
Most antibiotics incl. penicillins, cephalosporins, vancomycin, gentamicin, streptomycin Digoxin, atenolol Methotrexate SUs Furosemide Opioids
What drugs are considered safe to use in CKD?
Antibiotics - erythromycin, rifampicin
Diazepam
Warfarin
What antihypertensive may be useful in CKD when GFR falls <45ml/min?
Furosemide (as it lowers K)
Anaemia in CKD prediposes to what?
Development of LVH
What does ESA stand for?
Erythropoiesis stimulating agents
Give e.g.s of ESAs
Erythropoetin
Darbepoetin
How may renal bone disease manifest?
Osteitis fibrosa cystica (hyperparathyroid bone disease)
Adynamic (reduction in osteoblasts + osteoclasts)
Osteomalacia
Osteosclerosis
Osteoporosis