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
