Renal: CKD & AKI Flashcards
Give some causes of CKD
1) Diabetes
2) HTN
3) Medications (e.g. NSAIDs or lithium)
4) Glomerulonephritis
5) Polycystic kidney disease
Presenation of CKD?
- Often asymptomatic
- Fatigue
- Pallor (due to anaemia)
- Foamy urine (proteinuria)
- Nausea
- Loss of appetite
- Pruritus (itching)
- Oedema e.g. ankle swelling, weight gain
- Hypertension
- Peripheral neuropathy
What is estimated glomerular filtration rate (eGFR)?
It estimates the glomerular filtration rate (the rate at which fluid is filtered from the blood into Bowman’s capsule).
How is proteinuria quantified in CKD?
with a urine albumin:creatinine ratio (ACR).
What sample should be used for assessing proteinuria in CKD?
should be a first-pass morning urine specimen
What ACR is defined as clinically important proteinuria?
a confirmed ACR of 3 mg/mmol or more
What ACR is:
a) Normal to mildly increased
b) Moderately increased
c) Severely increased
a) <3
b) 3-30
c) >30
How can haematuria be assessed?
urine dipstick or microscopy.
Microscopic vs macroscopic haematuria?
Microscopic haematuria is when blood is identified on testing but not visible on inspection.
Macroscopic haematuria refers to visible blood in the urine.
What can haematuria indicate?
Infection, malignancy (e.g., bladder cancer), glomerulonephritis or kidney stones.
What investigations are required in CKD?
1) Renal ultrasound helps identify obstructions (e.g., kidney stones or tumours) and polycystic kidney disease.
2) Blood pressure (for hypertension)
3) HbA1c (for diabetes)
4) Lipid profile (for hypercholesterolaemia)
When can a diagnosis of CKD be made?
A diagnosis can be made when there are consistent results over three months of either:
1) Estimated glomerular filtration rate (eGFR) is sustained below 60 mL/min/1.73 m2
2) Urine albumin:creatinine ratio (ACR) is sustained above 3 mg/mmol
CKD can be classified according to a ‘G score’ and an ‘A score’.
What is the G score based on?
What is the A score based on?
G score based on eGFR
A score based on the albumin:creatinine ratio.
Describe G stage 1 to 5 in CKD
G1: eGFR >90
G2: 60-80
G3a: 45-59
G3b: 30-44
G4: 15-29
G5: under 15
Describe A stage 1 to 3 in CKD
A1: ACR under 3 mg/mmol
A2: 3-30 mg/mmol
A3: Above 30 mg/mmol
What is accelerated progression in CKD?
a sustained decline in the eGFR within one year of either 25% or 15 mL/min/1.73 m2.
Complications of CKD?
1) Anaemia
2) Renal bone disease
3) Cardiovascular disease
4) Peripheral neuropathy
5) End-stage kidney disease
6) Dialysis-related complications
Most significant cause of anaemia in CKD?
reduced erythropoietin (EPO) levels.
What type of anaemia does CKD cause?
This is usually a normochromic (normal colour) normocytic (normal size) anaemia
At what eGFR does anaemia typically become apparent in CKD?
when the GFR is less than 35 ml/min (other causes of anaemia should be considered if the GFR is > 60 ml/min).
What does anaemia in CKD predispose to?
To the development of left ventricular hypertrophy (associated with a three fold increase in mortality in renal patients)
What is EPO?
A hormone produced by the kidneys that stimulates erythropoiesis in the bone marrow
How does reduced EPO in CKD lead to anaemia?
EPO is produced by the kidneys.
In CKD, there is less EPO reduced, meaning reduced RBC production.
Give some ways the CKD can cause bone problems
1) low vitamin D (1-alpha hydroxylation normally occurs in the kidneys)
2) high phosphate
3) low calcium: due to lack of vitamin D, high phosphate
4) secondary hyperparathyroidism: due to low calcium, high phosphate and low vitamin D
Treatment of anaemia in CKD?
Erythropoiesis-stimulating agents, such as recombinant human erythropoietin.
Blood transfusions can sensitise the immune system (allosensitization), increasing the risk of future transplant rejection.
What is treated before using erythropoeitin in anaemia in CKD?
Iron deficiency –> IV iron is usually given, particularly in dialysis patients.
Cause of increased phosphate in CKD?
Reduced phosphate excretion by kidneys
Cause of low vit D in CKD?
Healthy kidneys metabolise vitamin D into its active form.
Cause of low serum calcium in CKD?
1) Active vitamin D is essential in calcium absorption in the intestines and reabsorption in the kidney
2) Also responsible for regulating bone turnover and promoting bone reabsorption to increase the serum calcium level
How do parathyroid glands react to low serum calcium and high serum phosphate in CKD?
Excrete more PTH, causing secondary hyperparathyroidism.
Impact of PTH on bone?
Parathyroid hormone stimulates osteoclast activity, increasing calcium absorption from bone.
Bone complications in CKD?
1) Osteomalacia: due to increased turnover of bones without adequate calcium supply
2) Osteosclerosis: occurs when the osteoblasts respond by increasing their activity to match the osteoclasts, creating new tissue in the bone (due to the low calcium level, this new bone is not properly mineralised)
3) Osteitis fibrosa cystica (aka hyperparathyroid bone disease)
4) Adynamic: reduction in cellular activity (both osteoblasts and osteoclasts) in bone (may be due to over treatment with vitamin D)
5) Osteoporosis: treat with bisphosphonates
Characteristic xray finding in renal bone disease?
Rugger jersey spine
What is Rugger jersey spine?
This involves sclerosis of both ends of each vertebral body (denser white) and osteomalacia in the centre of the vertebral body (less white).
The name refers to the stripes found on a rugby shirt.
What is osteosclerosis?
Osteosclerosis is a disorder that is characterized by abnormal hardening of bone and an elevation in bone density.
Management of renal bone disease?
- Low phosphate diet
- Phosphate binders
- Active forms of vitamin D (alfacalcidol and calcitriol)
- Ensuring adequate calcium intake
Overall aim of management in renal bone disease?
reduce phosphate and parathyroid hormone levels.
1st line for HTN in CKD?
ACEi - these are particularly helpful in proteinuric renal disease e.g. diabetic nephropathy
How can ACEi affect creatinine?
What rise is acceptable?
As these drugs tend to reduce filtration pressure a small fall in glomerular filtration pressure (GFR) and rise in creatinine can be expected.
NICE suggest a rise in creatinine of up to 30% is acceptable.
ACEi are offered to ALL patients with:
1) Diabetes plus a urine ACR above 3 mg/mmol
2) Hypertension plus a urine ACR above 30 mg/mmol
3) All patients with a urine ACR above 70 mg/mmol