Chronic kidney disease (URO) Flashcards
Define chronic kidney disease.
CKD is defined as abnormalities of kidney structure or function (GFR<60mL/minute/1.73m^2), present for >=3 months, with implications for health
What are abnormalities in kidney structure and function found in chronic kidney disease?
GFR >60mL/minute/1.73m^2 OR the presence of one or more of the following:
- albuminuria/proteinuria
- urine sediment abnormalities e.g. haematuria
- electrolyte abnormalities due to tubular disorders
- abnormalities detected by histology
- structural abnormalities detected by imaging
- Hx of kidney transplantation
What are some causes of chronic kidney disease? (5)
- diabetic nephropathy (diabetes)
- hypertensive nephropathy (hypertension)
- glomerulonephritis
- polycystic kidney disease
- heat stress nephropathy (environment/climate)
What are the most common causes of chronic kidney disease? (2)
Diabetes mellitus & hypertension
What is the most common genetic cause of chronic kidney disease?
Polycystic kidney disease
- autosomal dominant
- screen relatives with abdominal ultrasound
What are the mechanisms of damage in chronic kidney disease?
(Low-yield)
- renal injury –> increased intra-glomerular pressure + glomerular hypertrophy as compensation to maintain filtration
- glomerular permeability to TGF-beta, fatty acids, pro-inflammatory markers + protein –> mesangial matrix expansion, inflammation, fibrosis + scarring
- increase in angiotensin II –> upregulates TGF-beta –> collagen synthesis + scarring
- inflammation + reduced blood supply –> tubulo-atrophy + interstitial fibrosis
What are clinical features of CKD mainly manifestations of? (3)
- uraemia - lack of excretion of toxic substances
- anaemia - lack of EPO produced by kidney
- hyperphosphatemia - lack of excretion of toxic substances
How can CKD often present?
Often asymptomatic - may be finding of routine blood test or urine test
What are the clinical features of CKD?
- fatigue (uraemia/anaemia)
- oedema (peripheral/pulmonary - due to salt and water retention + hypoalbuminemia)
- nausea and vomiting (urea accumulation)
- pruritus (urea accumulation)
- restless legs (uraemia)
- anorexia (urea accumulation)
- foamy urine (proteinuria)
- cola-coloured urine (haematuria)
- dyspnoea, orthopnoea (pulmonary oedema due to reduced urine output)
- Kussmaul’s respiration (metabolic acidosis, deep inspiratory efforts without tachypnoea)
- seizures (advanced disease, increase in unexcreted toxins)
- infection-related glomerular disease (hepB&C, syphilis, streptococcal pharyngitis)
- arthralgia & rashes (concomitant autoimmune disorder)
- enlarged prostate gland (obstructive uropathy)
- symptoms of hypocalcaemia (due to 1-alpha-hydroxylase deficiency)
What are the symptoms of hypocalcaemia in CKD? (4)
- Convulsions (muscle twitching)
- Arrhythmias
- Tetany
- Paraesthesia
(CATs go NUMB)
What might you find on examination of a patient with CKD? (7)
- skin pigmentation
- uraemic frost
- purpura
- hypertension
- peripheral vascular disease
- cardiac arrhythmias: increased K+
- asterixis in encephalopathy
What are the risk factors for CKD?
- diabetes mellitus
- hypertension
- age>50
- childhood kidney disease
- smoking
- obesity
- black/Hispanic ethnicity
- Fx of CKD
- autoimmune disorders
- male sex
- long-term NSAID use
- high uric acid levels
What are the 1st-line investigations for CKD?
- renal chemistry (U&Es)
- estimation of GFR (equation using serum creatinine)
- serum cystatin C and cystatin C-based estimation of GFR (when serum creatinine inaccurate e.g. extremes of muscle mass)
- urinalysis
- urinary albumin (ACR)
- renal ultrasound
What do U&Es (renal chemistry/profile) show for CKD?
- elevated serum creatinine (may be falsely low in conditions of low muscle mass e.g. older, malnourished, liver failure)
- electrolyte abnormalities (tubular disorders –> metabolic acidosis) e.g. hyperkalaemia, hypocalcaemia
What can indicate if kidney injury is chronic and not acute?
Hypocalcaemia
(Kidney cannot produce 1-alpha-hydroxylase)
What is the GFR in CKD?
<60mL/minute/1.73m^2
When is GFR not a good measurement in CKD?
- reduced muscle mass –> overestimation of GFR
- increased muscle mass –> underestimation of GFR
What can urinalysis show for CKD?
Haematuria and/or proteinuria
What results does ACR (urinary albumin) show for CKD?
To check for proteinuria
Moderately increased ACR 30-300mg/g
What is the 1st-line imaging modality for kidney structure and what might you see (CKD)?
Renal ultrasound - small kidney size; presence of obstruction/hydronephrosis; kidney stones
(Large kidneys if diabetes uncontrolled in early diabetic kidney disease)
What might BNP be like in CKD?
Renal dysfunction (GFR<60) can cause a raised serum natriuretic peptides
What might FBC show in CKD?
Normocytic, normochromic anaemia due to EPO deficiency
When is kidney biopsy done for CKD?
For infectious causes, glomerular nephrotic and nephritic syndromes
What calcium/phosphate/PTH levels would we see in CKD?
- low calcium
- high phosphate
- high PTH
- low vitamin D
What are the stages of CKD?
- G1: eGFR>90ml/min + signs of kidney damage on other tests
- G2: eGFR 60-90ml/min + signs of kidney damage on other tests
- G3a: eGFR 45-59ml/min, moderate reduction in kidney function
- G3b: eGFR 30-44ml/min, moderate reduction in kidney function
- G4: eGFR 15-29ml/min, severe reduction in kidney function
- G5: eGFR<15ml/min, established kidney failure - dialysis or kidney transplant may be needed
What does G1 and G2 need to be classified as CKD?
Markers of kidney disease e.g. proteinuria, haematuria, electrolyte abnormalities, structural abnormalities
What can be used if eGFR is thought to be inaccurate?
Serum cystatin C, cystatin C-based eGFR
What are the stages of albuminuria for CKD?
- A1: <30mg/g or <3mg/mmol
- A2: 30-300mg/g or 3-30mg/mmol (microalbuminuria)
- A3: >300mg/g or >30mg/mmol (macroalbuminuria)
What GxAy stages of CKD correspond to what type of risk of progression and complications?
- low risk: G1A1 and G2A1
- moderate risk: G3aA1, G1A2, G2A2
- high risk: G3bA1, G3aA2, G1A3, G2A3
- very high risk: G4A1, G5A1, G3bA2, G4A2, G5A2, G3aA3, G3bA3, G4A3, G5A3
What are some differential diagnoses for CKD? (6)
- diabetic kidney disease
- hypertensive nephrosclerosis
- ischaemic nephropathy (long-standing essential hypertension that is suddenly uncontrolled)
- obstructive uropathy
- nephrotic syndrome
- glomerulonephritis
What is the 1st line treatment for G1-G4 CKD without uraemia?
-
1st line: ACEi or ARB (controlling BP, reducing proteinuria)
- lisinopril if ACR>30mg/mmol
- losartan
- 2nd line: non-dihydropyridine CCB
- consider dapagliflozin (SGLT2 inhibitor)
- PLUS statin (+/- ezetimibe if G3-4)
- consider additional antihypertensive therapy
- consider glycaemic control
When is dapagliflozin contraindicated in CKD?
eGFR<30ml/min/1.73m^2 (G4-5) including patients with end-stage renal disease who are on dialysis
How do we manage anaemia in CKD?
- IV iron (ferrous sulphate) to correct iron deficiency
- EPO-stimulating agents: epoetin alfa (correct iron deficiency before starting)
- aim for 10-11g/dl
How do we manage secondary hypoparathyroidism (due to low calcium) in CKD?
- dietary modification (reduce phosphate intake)
- phosphate-binding drug: sevelamer
- ergocalciferol (alfacalcidol)
- active vitamin D analogue (calcitriol)
How do we manage metabolic acidosis in CKD?
Oral sodium bicarbonate
What is key for management of proteinuria in CKD?
ACEi
What are the 1st and 2nd line treatments for CKD G5 or with uraemia?
- 1st line: dialysis (haemodialysis or peritoneal dialysis)
- 2nd line: kidney transplant
What type of dialysis is more common?
Haemodialysis more common than peritoneal dialysis
How does haemodialysis work?
- patient’s blood is removed from body through an arteriovenous fistula/graft/dialysis catheter and then returned after traversing a dialysis membrane/solution
- usually in hospital 3x a week, 4h each session
How does peritoneal dialysis work?
- catheter inserted into abdomen and dialysis fluid is instilled in order to allow for toxic waste products to be removed on a daily basis
- done at home
- continuous cycling peritoneal dialysis is done with a machine at night on a daily basis
- continuous ambulatory peritoneal dialysis is done on a daily basis
What organism is the most common cause of peritonitis in peritoneal dialysis?
Staphylococcus epidermidis
Diffuse tenderness + rebound tenderness and guarding on examination
If a patient gets ill soon after a kidney transplant, what is the most likely cause?
Cytomegalovirus
What condition can the immunosuppressives e.g. ciclosporin taken after kidney transplant cause?
Squamous cell carcinoma of skin
What are some other principles of management of CKD? (4)
- fluid and salt restrictions to maintain fluid balance
- EPO-stimulating agents (correct iron deficiency first)
- vitamin D supplements - alfacalcidol (does not require activation in kidneys)
- reduce dietary intake of phosphate or phosphate binders (sevelamer or alendronic acid) - try dietary reduction first
What type of drugs are avoided in CKD?
NSAIDs and other nephrotoxic drugs
When do NICE guidelines suggest referring to a nephrologist from primary care for CKD?
If eGFR<30 or falls progressively by >15 in a year
What are some complications of CKD? (7)
- anaemia
- renal osteodystrophy (due to low calcium + high PTH –> high phosphate)
- cardiovascular disease (CKD on haemodialysis - most likely cause of death is IHD)
- protein malnutrition (anorexia, N&V, lack of protein intake)
- metabolic acidosis (inability to excrete acid once eGFR<50ml/min)
- hyperkalaemia (may cause muscle weakness, ECG peaked T-waves, treat with IV calcium, insulin + dextrose, beta agonists, loop diuretics, oral potassium binders, haemodialysis)
- pulmonary oedema (treatment of fluid overload with loop diuretic)
Describe the prognosis of CKD.
- mostly progressive and leads to end-stage renal disease and the need for renal replacement therapy
- cannot be cured, but can be controlled and managed
