Case 10 - Chronic renal failure Flashcards
What is the definition of chronic kidney disease?
An estimated or measured glomerular filtration rate (GFR) <60 mL/min/1.73m2 that is present for at least 3 months, with or without evidence of kidney damage.
OR
Evidence of kidney damage, with or without decreased GFR that is present at least 3 months, as evidenced by:
- Albuminuria
- Haematuria
- Structural abnormalities (eg on kidney imaging tests) or
- Pathological abnormalities (eg on kidney biopsy)
What are the 2 most common cause of end-stage kidney disease in Australia?
Diabetes
Chronic hypertension
What is the typical presentation of someone with CKD?
Usually asymptomatic.
HTN or CKD complications (e.g. elevated serum creatinine) may be discovered during a routine evaluation or as tests for another issue
What is the timeline demarcating AKI vs. CKD?
AKI = <3 months
CKD = >3 months
Why are patients usually asymptomatic until they reach the later stages of CKD?
Kidneys have exceptional compensatory ability
Name 5 risk factors for CKD
- Diabetes
- HTN
- Smoking
- Obesity
- Advanced age (>60)
- AKI
- FHx of CKD
The presence of certain abnormalities/clinical markers are required for >3 months in order to diagnose someone with CKD. Name these abnormalities.
- Albuminuria (measured using ACR)
- Electrolyte imbalances
- Retention of nitrogenous wastes (urea, creatinine, ammonia, etc)
- Acid-base imbalances
- Decreased EPO production
- Imaging showing structural abnormalities (e.g. polycystic kidneys)
Name the 2 CATEGORIES of clinical manifestations that patient with CKD may develop
- Manifestations of Na+ / H2O retention
2. Manifestations of uraemia
Describe the early, nonspecific manifestations which may appear in CKD
- Weakness
- Fatigue
- Anorexia
List the manifestations of Na+ / H2O retention that may appear in CKD
- Pulmonary oedema
- Peripheral oedema
- Hypertension
- Heart failure
What is uraemia?
The constellation of signs/symptoms that manifest in ESKD
Describe the constitutional symptoms of uraemia
- Headache
- Weakness
- Fatigue
Describe the GIT manifestation of uraemia
- NV
- Anorexia
- Uraemic fetor (ammonia / urine-like breath odour)
Describe the dermatological manifestations of uraemia
- Pruritus
- Skin colour changes (e.g. hyperpigmentation or pallor due to anaemia)
- Uraemic frost
What is uraemic frost?
High levels of urea in the blood leading to urea being secreted in sweat. Once it evaporates there may be tiny crystallised yellow-white urea deposits on the skin
Describe the serous manifestations of uraemia
Serositis causing:
- Uraemic pericarditis
- Pleuritis
Describe the neurological manifestations of uraemia
- Encephalopathy (coma, seizures, somnolence)
- Asterixis
- Parasthesia (caused by peripheral neuropathy)
Describe the haematological manifestations of uraemia
- Anaemia (due to increased destruction of RBCs)
- Leukocyte dysfunction (frequent infections, easy bleeding)
What are the 4 most common causes of CKD in Australia?
- Diabetes
- Hypertension
- Glomerulonephritis
- Polycystic Kidney Disease
Can you have a normal GFR but still be diagnosed with CKD?
YES - in this case, urine albumin excretion will be abnormal
Evidence of kidney damage for >3 months is one of the definitions of CKD. List the parameters used to define kidney damage
- Albuminuria
- Haematuria after exclusion of urological causes
- Structural abnormalities (eg on kidney imaging tests)
- Pathological abnormalities (eg on kidney biopsy - not routinely done)
Which lab abnormalities are most common in CKD?
- Increased serum creatinine
- Increased blood urea & nitrogen
What is the most frequently assessed marker of kidney damage in clinical practice?
Albuminuria, as measured using the ACR / Albumin-creatinine ratio
What are the definitions of a normal ACR, microalbuminuria, and macroalbuminuria?
NORMAL ACR: <2.5 in males, <3.5 in females
MICROALBUMINURIA: <2.5-25 in males, <3.5-35 in females
MACROALBUMINURIA: >25 in males, >35 in females
units: mg/mmol
What you might expect to find in the following laboratory tests in someone with CKD?
- CBE
- Biochemistry
- Coagulation screen
- Urine ACR
- Fasting lipids
- Urinalysis
- CBE: normochromic, normocytic anaemia
- Biochemistry: inc. BUN + creatinine, hyperkalemia, possible hyperphosphatemia and hypocalcemia
- Coagulation screen: increased bleeding time
- Urine ACR (first-morning void): raised
- Fasting lipids: dyslipidaemia
- Urinalysis: abnormal urine sediment, waxy casts
Describe the pathophysiology of CKD resulting from diabetic nephropathy
- Excess blood glucose
- Non-enzymatic glycation: glucose molecules stick to proteins
- Hyaline arteriosclerosis –> narrowing of afferent arteriole
- Increased resistance in the nephrons
- High-pressure state causes mesangial cells to secrete more structural matrix
- Expands the size of the glomerulus
- Glomerulosclerosis diminishes the nephron’s ability to filter blood –> CKD
Name 2 causes of CKD that aren’t HTN or diabetes
Systemic diseases: lupus, RA
Medications: NSAIDs
Infections: HIV
Toxins: tobacco
Outline the 2 mechanisms of kidney damage in chronic hypertension (below + above protective autoregulatory threshold)
BELOW AUTOREGULATORY THRESHOLD: benign nephrosclerosis (sclerosis of the afferent arterioles & small arteries) –> thickening –> decreased perfusion –> ischaemic damage
ABOVE AUTOREGULATORY THRESHOLD: acute injury –> malignant nephrosclerosis –> bunch of bad shit happens –> failure of autoregulatory mechanisms –> damage
What is glomerulonephritis?
A group of diseases characterised by glomerular cell proliferation, inflammation, and leukocyte infiltration.
Characteristically presents with nephritic syndrome, but isolated nephrotic syndrome and nephrotic-nephritic syndromes can also occur.
Name 6 complications of CKD
- Chronic kidney disease-mineral & bone disorder (CKD-MBD)
- Secondary hyperparathyroidism
- Anaemia of chronic kidney disease
- Delayed growth (in children)
- Cardiovascular disease
- ESRD (end-stage renal disease)
Use the acronym Kidney OUTAGES to list some of the complications of CKD
Kidney - hyperKalaemia
O - renal osteodystrophy (CKD-MBD) U - uraemia T - triglyceridaemia A - acidosis (metabolic) G - growth delay E - erythropoietin (anaemia) S - sodium/water retention
How does CKD lead to arrhythmias?
CKD –> decreased K+ secretion –> hyperkalemia –> defective electrical conduction through cardiac myocytes –> arrhythmias
How does CKD lead to anaemia?
CKD –> less EPO production –> decreased RBC production –> anaemia
How does CKD lead to renal osteodystrophy? (a form of metabolic bone disease seen in patients with chronic renal insufficiency characterized by bone mineralization deficiency due to electrolyte and endocrine abnormalities)
CKD –> decreased calcitriol production –> decreased intestinal calcium absorption –> hypocalcemia –> renal osteodystrophy
What are the components of nephritic syndrome?
- HAEMATURIA with acanthocytes (dysmorphic RBCs)
- RBC CASTS IN URINE
- PROTEINURIA (<3.5g/day)
- HYPERTENSION
- OEDEMA
- Sterile pyuria
- Oligouria
- Azotemia
List 4 factors that influence serum creatinine
- Age
- Sex
- Muscle mass
- Diet
- Medications (e.g. trimethoprim)
Should creatinine levels be used to detect renal impairment?
NOOOOOO
You can have normal creatinine despite having RENAL IMPAIRMENT
Should creatinine levels be used to detect renal impairment?
NOOOOOO
You can have normal creatinine despite having RENAL IMPAIRMENT
How does kidney impairment impact the plasma concentration of a drug?
CLEARANCE is reduced in renal impairment, so the CONCENTRATION of the drug INCREASES
C(steadystate) = dosing rate / clearance
Which types of opioids are preferentially used in renal impairment? Why?
In patients with renal impairment, prefer to use: oxycodone, fentanyl.
Opioids such as codeine and morphine are metabolised by the liver BUT produce METABOLITES that are cleared by the kidneys. These active metabolites build up and can cause complications (e.g. seizures)