Renal Medicine - Chronic Kidney Disease Flashcards
What is chronic kidney disease (CKD)?
Presence of kidney damage, manifested by abnormal albumin excretion or decreased kidney function, quantified by measured or estimated GFR that persists for more than three months.
Give some causes of CKD.
- diabetes
- hypertension
- glomerulonephritis
- polycystic kidney disease
- medications (e.g. NSAIDs, PPIs)
Risk factors for CKD.
- increasing age
- hypertension
- diabetes
- smoking
- use of nephrotoxic medications
Presentation of CKD.
Usually asymptomatic and diagnosed on routine testing.
How is CKD investigated?
eGFR using U&Es blood test
Proteinuria can be checked using a urine albumin:creatinine ratio (ACR) - a result of ≥ 3mg/mmol is significant.
Urine dipstick for haematuria - presence should prompt investigation for malignancy.
Renal ultrasound can be used to investigate some patients.
How is CKD staged?
Patients given a G score and an A score.
G score is based upon eGFR:
G1 = eGFR >90
G2 = eGFR 60-89
G3a = eGFR 45-59
G3b = eGFR 30-44
G4 = eGFR 15-29
G5 = eGFR <15 (known as “end-stage renal failure”)
A score is based upon ACR:
A1 = < 3mg/mmol
A2 = 3 – 30mg/mmol
A3 = > 30mg/mmol
The patient does not have CKD if they have a score of A1 combined with G1 or G2. They need at least an eGFR of < 60 or proteinuria for a diagnosis of CKD.
What are some complications of CKD?
- anaemia
- renal bone disease
- cardiovascular disease
- peripheral neuropathy
- dialysis related problems
NICE suggests referral to specialist in CKD when:
- eGFR < 30
- ACR ≥ 70mg/mmol
- accelerated decrease in eGFR
- uncontrolled hypertension
What are the aims of CKD management?
- slow the progression of the disease
- reduce risk of CVD
- reduce risk of complications
- treat complications
How can the progression of CKD be slowed?
- optimise diabetic control
- optimise hypertensive control
- treat glomerulonephritis
How can the risk of complications from CKD be reduced?
- exercise to maintain a healthy weight
- smoking cessation
- special dietary advice
- offer atorvostatin 20mg OD for primary prevention of CVD
Which antihypertensive medication is first line in patients with CKD?
ACE inhibitors, for example ramipril.
Aim to keep blood pressure <140/90 (or < 130/80 if ACR > 70mg/mmol).
Serum potassium needs to be monitored as chronic kidney disease and ACE inhibitors both cause hyperkalaemia.
Outline the association between CKD and anaemia of chronic disease.
Chronic damage to the kidney parenchyma causes a drop in erythropoietin, meaning there is less erythropoiesis. This causes a drop in red blood cells and subsequent anaemia.
What are the three main features of renal bone disease?
- osteomalacia
- osteoporosis
- osteosclerosis
Pathophysiology of renal bone disease.
- Damaged renal parenchyma is not able to metabolise vitamin D into its active form.
- Calcium reabsorption in the intestines and kidneys reduced, therefore serum calcium reduces.
- Secondary hyperparathyroidism occurs in reaction to the low serum calcium, increasing osteoclast activity (osteomalacia).
- Osteoblasts respond by increasing their activity to match the osteoclasts (osteosclerosis), however due to the low calcium level in tissue this is not properly mineralised (osteoporosis).
How does hypertension lead to CKD?
Chronic hypertension leads to nephrosclerosis, which causes loss of renal parenchyma and replacement with scar tissue.
AKA hypertensive nephropathy.
What is diabetic nephropathy?
Chronic high levels of glucose passing through the glomerulus causes glomerulosclerosis (ie. scarring).
Proteinuria ensues due to damage to the glomerulus, allowing protein to be filtered from blood to urine.
What is polycystic kidney disease?
A genetic condition where the kidneys develop multiple fluid-filled cysts, causing significant function impairment.
Which genetic mutations are associated with ADPKD?
- PKD-1: chromosome 16 (85%)
- PKD-2: chromosome 4 (15%)
What are the extra-renal manifestations of ADPKD?
- cerebral aneurysms
- hepatic, splenic, pancreatic, ovarian or prostatic cysts
- mitral regurgitation
- colonic diverticula
- aortic root dilatation
What are the complications of ADPKD?
- chronic loin pain
- hypertension
- cardiovascular disease
- gross haematuria in cyst rupture
- renal stones
- ESRF
What genetic mutations are associated with ARPKD?
Gene on c’some 6 causes a rarer, more severe kidney dysfunction.
What are the features of ARPKD?
Severe renal dysfunction presents as oligohydramnios in pregnancy, as the foetus does not produce enough urine.
This leads to underdevelopment of the foetal lungs, resulting in respiratory failure shortly after birth. Most babies will die shortly after birth and, if they do survive, will have ESRF by adulthood.
How should polycystic kidney disease be managed?
- control BP
- tolvaptan (vasopressor antagonist) can slow the development of cysts and progression to ESRF
- genetic counselling and testing
Below an eGFR of what value would a person be considered to be in ESRF?
eGFR < 15
What is the treatment option for ESRF?
Transplantation is treatment of choice.
Haemodialysis or peritoneal dialysis can be used in earlier stages of CKD.
Which scar upon examination is characteristic of renal transplantation?
“Hockey-stick” scar
How is donor compatability assessed in renal transplantation?
Patient and donor kidneys matched based upon:
- HLA A
- HLA B
- HLA C
- c’some 6
Patients do not have to fully match, however the closer the match the more likely the transplant is successful.
Outline the procedure of renal transplantation.
The patient’s own kidneys are left in place. The donor kidney’s blood vessels are connected (anastomosed) with the patient’s pelvic vessels, usually the external iliac vessels.
The donor kidney’s ureter is anastomosed directly with the patient’s bladder. The donor kidney is placed anterior in the abdomen and can usually be palpated in the iliac fossa area.
They typically use a “hockey stick incision” and there will be a “hockey stick scar”.
How is a patient managed post-renal transplantation?
The new kidney will start functioning immediately.
Patients require lifelong immunosuppression to reduce the risk of transplant rejection. A usual regime is:
- tacrolimus
- mycophenolate
- prednisolone
What are the complications of renal transplantation?
- transplant rejection (hyperacute, acute and chronic)
- transplant failure
- elecytolyte imbalances
- surgical and anaesthetic risks associated with procedure
Give some complications associated with immunosuppressant therapy.
- ischaemic heart disease
- T2DM
- infection
- non-Hodgkin lymphoma
- skin cancer (particularly SCC)
What are the advantages of renal transplantation?
- near normal lifestyle
- better mortality / morbidity
What are the disadvantages of renal transplantation?
- criteria to meet suitability to safely undergo operation
- compliance with medication lifelong
- risk of rejection
- risk of malignancies
- risk of infection
- long waiting times, esp. for cadaveric organ
In which patient demographics is renal replacement therapy thought to have no survival benefit?
- age > 80yrs
- WHO performance score ≥ 3
In this case, active conservative management is likely to be initiated.
What is active conservative management of ESRF?
Decision made after discussion with patient and family members, with pts unsuitable for invasive therapy such as PD / HD / transplantation.
Active conservative management of ESRF:
- symptom control to enhance quality of life
- respect patients preferred place of care
- advance care plan
- MDT approach
- support system for patients and family
