Chronic Kidney Disease Flashcards
What is the traditional definition of chronic renal failure?
Irreversible and significant loss of renal function
How do we assess for kidney disease?
Excretory function
-Glomerular Filtration Rate (eGFR from creatinine blood test)
Filtering function
-Check for presence of blood or protein in urine
Anatomy
-Histology, radiology
What is the problem with the relationship between serum creatinine and GFR (for measuring eGFR)?
Creatinine will not be raised above the normal range until 60% of total kidney function is lost
What effects serum creatinine levels?
Muscle mass:
- Age,
- Ethnicity (African Americans)
- Gender (Male)
- Weight
Give some formulae to estimate GFR from serum creatinine
Cockcroft Gault
MDRD 4 variable equations
CKD-EPI equation
What crosses the GBM?
Water
Electrolytes
Urea
Creatinine
What crosses the GBM but is reabsorbed in the proximal tubule?
Glucose
Low molecular weight proteins (a2-microglobulin)
What doesnt cross the GBM?
Cells (RBC, WBC)
High molecular weight proteins (albumin, globulins)
How much blood or protein should you be able to measure in a normal kidney?
Should be no blood or protein measurable in urine if filtering properly
How can you test for protein or blood in urine?
Urinalysis (“dipstick”)
- Blood
- Protein
Protein quantification
-Protein creatinine ratio (PCR)
What is the current chronic kidney disease definition?
Chronic kidney disease is defined by either the presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR /= 3 months
What is the prevelence of CKD?
Increases with age
About 8-12% in UK
Mostly stage 3
Give some of the complications of chronic kidney disease
Acidosis Anaemia Bone disease Cardiovascular Death and dialysis ELectrolytes Fluid overload Gout Hypertension Iatrogenic issues
How much does CKD cost?
About £35,000pa for 1 patient
Around £6,500 drug costs
£20,000 transplant
What is the aetiology of CKD?
Polycystic kidney disease
Diabetes
Glomerulonephritis
-And all the causes of that
Hypertension
Renovascular disease
etc
What is the clinical approach to CKD?
Detection of the underlying aetiology
-Treatment for specific disease
Slowing the rate of renal decline
-Genetic therapies
Assessment of complications related to reduced GFR
-Prevention and Treatment
Preparation for Renal replacement therapy
What are you looking for in terms of previous evidence of renal disease in a CKD history
Raised urea/ creatinine
Proteinuria/ haematuria
Hypertension
LUTS
What systemic diseases do you need to keep an eye out for in a CKD history?
Diabetes Mellitus
Collagen vascular diseases:
-SLE, Scleroderma, Vasculitis
Malignancy:
-Myeloma, Breast, lung, lymphoma
Hypertension
Sickle cell disease
Amyloidosis
What drugs are you keeping an eye out for in CKD history?
NSAIDs
Penicillins/ aminoglycosides
Chemotherapeutic drugs
Narcotic abuse
ACE inhibitor/ ARBs
What uraemic symptoms may you be looking for in a CKD history?
Nausea, anorexia, vomiting
Pruritus
Weight loss
Weakness, fatigue, drowsiness
What are some of the clinical signs of depleted volume status?
Orthostatic BP
Skin turgor/ temperature
What are some of the clinical signs of fluid overload?
Raised JVP
Crepitations
Ascites
Oedema
What chemistry investigations may you want to carry out to look for CKD aetiology?
U&E (Na, K, Cl)
Creatinine
Bicarbonate
Total protein, albumin
Calcium, phosphate
Liver function tests
Creatine Kinase
Immunoglobulins, serum protein electrophoresis
What haematology investigations may you want to carry out to look for CKD aetiology?
FBC
- Hb
- MCV
- MCH
- WBC
- Platelets
- % hypochromic RBCs
What will be included in a coagulation screen you may want to carry out?
PT
APPT
+/- Fibrinogen
What imaging may you want to carry out to find the aetiology of CKD?
Ultrasound
Plain radiology
CT Nuclear medicine
MRI
When can pathology be useful for finding the aetiology in CKD?
Unexplained renal failure and Normal sizes kidneys
How can you slow the rate of renal decline?
BP control
Control Proteinuria
Reverse other contributing factors - treat causes
Others:
- Allopurinol
- Dietary proetin restriction
- Fish oils
- Lipid lowering
- Control acidosis
What investigations can you carry out to assess complications related to reduced GFR?
Blood count and Film
- ?Anaemic
Calcium Phospate Albumin PTH
- ?Renal bone disease
Creatine Urea
- ?GFR
Bicarbonate
- ?Acidosis
Electrolytes
- ?Hyperkalaemia
Urine Protein excretion (Pr:Cr)
- ?Degree of proteinuria
When does anaemia usually manifest in CKD?
When GFR
Describe the anaemia resulting from CKD?
Normochronic Normocytic
Reduced erythropoietin production
Reduced red cell survival
Increased blood loss
How do you treat anaemia due to CKD?
Usually treat if
When is metabolic acidosis usually seen in CKD?
When is metabolic acidosis most marked?
Nor usually seen until GFR
What are the symptoms of metabolic acidosis due to CKD?
General symptoms
Worsens hyperkalaemia
Exacerbates renal bone disease
How do you treat metabolic acidosis in CKD?
Treat with oral Na Bicarbonate
-Care with volume overload
How does CKD result in bone disease?
Reduced GFR leads to hyperphosphataemia
Loss of renal tissue leads to lack of vitamin D
-(indirect reduction in Ca absorption)
Low Calcium and raised phosphate
Secondary hyperparathyroidism (elevtaed PTH)
May progress to tertiary hyperparathyroidism
How does CKD effect activation of vitamin D?
Vitamin D, derived from sunlight or diet, requires to be hydroxylated to be active - 1,25 (OH) 2 D
The 1a hydroxylation is catalysed by 1a hydroxylase in the kidney
CKD -> low 1a hydroxylase, so low activation of vitamin D
How does low vitamin D lead to low calcium?
Reduced intestinal absorption
Reduced tubular reabsorption
Resulting stimulation of PTH secretion (i.e. secondary hyperparathyroidism)
What does high phosphate levels cause?
Reduced 1a hydroxylase therefore low vitamin D
Stimulates PTH production
Associated with vascular and cardiac calcification
How do you manage renal bone disease?
Control phosphate
-Diet
- Phosphate binders
- –CaCO3, Ca Acetate, Sevelamer, lanthanum
Normalise Calcium and PTH
-Active Vit D analogues (Calcitriol)
- Tertiary disease
- –Parathyroidectomy and Calcimetics (Cinacalcet)
Why does CKD result in Hyperkalaemia?
Normally excreted by exchange with Na+ in distal tubule
Reduced delivary of Na+ to distal tubule as GFR falls
Other factors include underlying disease, drgs and diet
How do you treat acute hyperkalaemia?
Stabilise cardiac membrane
-Calcium Gluconate
Shift K+ into cells
- Salbutamol
- Insulin-Dextrose
Remove calcium from body:
- Dialysis
- Calcium resonium
How do you treat chronic hyperkalaemia?
Diet
Drug modifications
When does fluid/ volume overload become problomatic in CKD?
When GFR
How does CKD lead to fluid/ volume overload?
Unable to excrete an excess Na+ load
Na+ and water retention
Oedema and hypertension
How do you treat fluid overload in CKD?
Na+ restriction
Fluid restriction
Loop diuretics
How do you tackle hypertension in CKD?
Treatment as per slowing rate of progression
Most imporatnt in proteinuric renal disease
ACEI may offer additional advantage
Otherwise tailored therapy
Aim
What drugs should by be weary of in CKD?
The main effect of kidney disease is reduced excretion of drugs and their toxins
-Beware antibiotics, morphine, digoxin, metformin amongst others
In those with CKD certain drugs and agents can cause acute kidney injury on top of CKD:
-Contrast agents, antibiotics
What is associated with worse outcomes in CKD?
Worse kidney function (GFR)
More proteinuria
