Chronic Kidney Disease Flashcards
What test results are usually associated with CKD?
- High creatinine (advanced kidney disease)
- High potassium (poor GFR)
- Metabolic acidosis= low bicarbonate
- High blood pressure
- Haemoglobin low = tired, short of breath
- Calcium low= cramps
- Phosphate high= itchy skin
What type of effects does the kidneys have?
-Exocrine / excretory
=Fluid and electrolyte balance
(Blood pressure / electrolyte fine balance)
=Removal of toxins
-Endocrine effects
=Blood / Bone / Blood pressure
What is CKD?
GFR of less than 60 ml/min for >90 days /3 months
What are the causes of CKD?
- Diabetes
- Hypertension
- Glomerulonephritis
- Cystic kidney disease (APCKD)
- Renovascular disease
What are the consequences of CKD?
- Many of the problems caused by CKD start early
- Excretory / Endocrine effects
- Dialysis / Transplant / increased mortality and morbidity
How do we estimate renal function?
-Normal GFR= 125 ml/min/1.73m2
-Serum Creatinine – can be very misleading
-Creatinine clearance (24 hour urine collection)
=may be affected by age/ muscle mass/ drugs
=Urea and creatinine clearance more accurate
-Isotope GFRs -expensive and time consuming
-Formulae- for estimated GFR (MDRD) or Creatinine clearance (Cockcoft and Gault) – based on creatinine
What is needed for the Cockcoft and Gault equation?
- Creatinine level
- Lean bodyweight
- Age
- Adjustment factor for gender
What does the MDRD equation need?
- Age
- Serum creatinine
- Sex
- Racial adjustment factor
What are the stages of CKD?
- 5 Stages
- Based of GFR level
- Stage 1= 120 to 90 (plus radiographical/ biopsy evidence)
- Stage 2=90 to 60
- Stage 3=60 to 30
- Stage 4=30 to 15 (planning for dialysis)
- Stage 5=15 to 0 (transplant)
How common is CKD?
Epidemiological data (NHANEs – 2009-14)
-6.2 % population have CKD 3 (US/UK)
=Earlier studies 4.7%
-Given elderly population have more CKD, up to >25% of elderly pts may be expected to have Stage 3 CKD or worse
What strategies are used to prevent progression of CKD?
-Control blood pressure (RAS inhibition)
-Reduce proteinuria (RAS inhibition)
-If diabetes, optimise glycaemic control
-SGLT2 inhibitors
=CREDENCE trial - Renal outcome HR 0.70 / CV outcome HR 0.61
=DAPA-CKD trial –Renal outcome HR 0.56 / CV outcome HR 0.71
=EMPA-REG – Empaglifozin (results awaited)
Why is treatment of Diabetes and/or proteinuria with Renin-angiotensin blockade so important?
- If you have CKD, if you have minimum proteinuria= moderate risk
- If you have CKD, if you have heavy proteinuria= high risk of progression
How does proteinuria pose greater risk of CKD progression?
-Protein in filtrate taken up into tubular cells into lysosomes, broken down into amino acids and taken up into peritubular capillaries to be recycled
-If heavy proteinuria= overload the system so cells release free oxygen radicals and die
=Fibroblasts and macrophages clear away but leaves fibrosis behind
What action does ACE inhibitors have on preventing fibrosis?
- Efferent arteriole dilatation
- Reduced glomerular pressure
- Reduces proteinuria
What needs to be considered in drug management?
-Avoid potential toxins
=NSAIDs/ Contrast (imaging and CT scans)=hydration/ Gentamicin/ phosphate enemas (too much phosphate absorption)
-Drug dosing
Describe drug dosing in CKD
-Many drugs need to be given at lower doses in patients with CKD
=Especially chemotherapy agents/ antibiotics
=Many toxic agents will be contraindicated
-If in doubt, check BNF
-Rem: >25% of elderly pts may have CKD!
Describe Hypertension in ESRD (end-stage renal disease)
-Cause / consequence
-Causes Left Ventricular Hypertrophy (then heart failure)/ Stroke / End-organ damage- eyes/ kidneys
-BP treatment goals
“normal” - 130/80
DM / Proteinuria 125/75
-Rate of decline in GFR increases with hypertension
Why is controlling potassium important?
-Hyperkalaemia common as GFR declines < 25
=May occur at GFR>25 –Diabetes and type 4 RTA - ACE inhibitors - High K Diet
=Related to distal sodium delivery ( DND↓ with ↓ GFR decreases potassium absorption)
How can potassium levels be managed?
-Dietary advice re High K foods =Bananas =Crisps =Potatoes etc. -Potassium binders?? Patiromer / Sodium zirconium (agents which swallow during meals to bind in gut)
Describe Acidosis in renal failure
-Much acidosis in CRF is due to animal protein in food.
=Inability to acidify urine in CKD
=Phosphate / sulphates / other anions – v late
-Aim to keep Serum HCO3 >22
-Replace with NaHCO3 / Sodium Bicarbonate
=But beware fluid overload.
What are the excretory complications of CKD?
- Salt and Hypertension
- Potassium
- Acidosis
What are the endocrine complications of CKD?
- Anaemia
- Renal Osteodystrophy
- Cardiovascular risk
- Malnutrition
Describe anaemia in CKD
-Hb < 12 in males/ < 11 in females
=Generally normochromic normocytic anaemia
-Decreased response of EPO to an hypoxic stimulus (kidneys) and…..
=decreased red cell survival
=iron deficiency
=blood loss – dialysis / blood samples / GI
=aluminium / hyper PTH / B12+Folate deficiency
What is Erythropoietin Replacement Therapy?
-All patients with Hb <105 and adequate iron stores should be on Epo
=Better Quality of life / less dyspnoea / reduced Left Ventricular hypertrophy
-Target Hb 100-120 (debate++)
=S/E - hypertension / thrombosis if doses too large
-If poor response to EPO
=Check iron stores / CRP / B12 +folate / PTH/Aluminium/ ?malnutrition / ?malignancy
