CKD Flashcards
What are the differences between acute CKD?
Long lasting (>3 months)
Less severe
Can progress to severe disease
What are the functions of the kidney?
Remove waste products
Regulate ions in blood (K+, Ca2+, Na+)
Regulate water levels
Hormone production (EPO, vit D activation)
What is the functional unit of the kidney?
Nephron - 10^6 - Glomerulus, PCT, LoH, DCT, Collecting duct
What are the layers of the membrane between the glomerulus capillaries and bowmen capsule?
Fenestrated endothelium cells
Basesment membrane
Filtration slits in epithelial cells
Podocytes
What controls the rate of filtration in the glomerulus?
Afferent and Efferent BP
Increase Efferent BP (vasoconstriction) causes build of up of pressure in the glomerular capillaries and increases the rate of ultrafiltration
What can cause vasoconstriction in the efferent arteriole?
H20
Salt concentration
Prostaglandins
Angiotensin
What are the components of the membrane that create the negative charge?
Fenestrated endothelium - Podocalyxin
Basesment - Heparin sulphate prostoglycans
Podocytes - Podocalyxin
What is the rough limit of size of molecules to pass through the glomerulus?
50-60,000 mW
What are some examples of molecules filtered?
H20 K+ Urea Inulin Creatinine
What is not filtered?
Serum albumin
RBC
What is the measurement for measuring kidney function?
GFR = ml/min/1.73m2
How can we measure GFR?
Exogenous solutes - Inulin and Chromum51EDTA (Expensive, slow, exposure to radiation)
Endogenous solute - Creatinine
What is creatinine?
Produced in the liver, converted from creatine
Muscle stores around 100g creatine (as creatine phosphate - high energy phosphate donor)
Rate of conversion depends on liver function, muscle mass and muscle catabolism
Freely filtered at the glomerulus
What is the problem with measuring creatine clearance?
Requires measurement of urine over a 24 hour period – impractical
What is the problem with using plasma creatine as a surrogate measure for GFR?
Poor at extreme measures
Doesnt take into account muscle mass
Creatine is secreted by the tubules so is not a direct measure of GFR
Affected by exercise and protein intake
What are the validated formulas used to measure GFR?
Cockcroft-Gault - Gender, Age, Weight
MDRD (eGFR) - gender, age, ethnicity
CKD-EPI (Creatinine and CystatinC measurements)
What other measurements can we use to determine kidney health?
Proteinuria (albumin/creatinine ratio)
Heamaturia
Albumuria (24 hour urine measurement)
What defines CKD stages?
NKF-KDOQI (Kidney disease outcomes quality initiative)
What are the stages of CKD?
Stage 1 - Haematuria, Proteinuria, normal GFR (>90)
Stage 2 - Haematuria, Proteinuria, slightly reduced GFR (60-89)
Stage 3a - reduced GFR (45-59), Stage 3b (31-44)
Stage 4 - vastly reduced GFR (16-30)
Stage 5 - kidney failure (>15ml/min/1.73m2)
What are the stages of albuminuria?
A1 - <30
A2 - 31-299
A3 - >300
What are the advantages of the introduction of the NKF-KDOQI?
Standaradise CKD diagnosis around the world - increased comparisons between epidemiology studies
Increase awareness
Increase need for early diagnosis
What are the downside of the NKF-KDOQI?
Formula to calculate GFR not completely accurate - vary greatly with age, gender, ethnicity, pregnancy, extreme weights, diabetics
MDRD (eGFR) 30% of patients will get a result out by >30% - overestimation of CKD
What are the prevalence stats for CKD in the UK?
10.6% women
5.8% men
around 3 mill have CKD
60,000 have Stage 5 and require treatment - 19 per day
RRT - Dialysis - 500 mil, Transplant - 225 mil (2010)
What are the consequences of CKD?
Hyperkalaemia - High K - Arrthymia
Acidosis - Azotemia (urea) - weight loss, fatigue, nausea, asterixis
Hypocalcaemia - reduced activation of VitD - reduced calcium in blood - secondary hyperparathyroidism - calcium from bones - pain
Hyperphosphataemia - increased PO4 - leads to hypocalcaemia
Renal Anaemia - reduced EPO - fatigue, weight loss
Fluid retention - oedema
Hypertension - increased renin - increased BP
