Chronic Kidney Disease Flashcards
Again - functions of kidney (3 homeostasis, 2 function, 1 regulation)
Body fluid homeostasis
Acid-base homeostasis
Electrolyte homeostasis
Excretory function
Endocrine function
Regulation of vascular tone
3 things to measure in kidney disease? How do we measure?
- FILTRATION (excretion) function - use estimates of GFR (eGFR) from creatinine blood test
- FILTRATION (keep in/barrier) function - check for presence of blood or protein in urine
- ANATOMY - histology, imaging
4 methods for measuring excretory renal function?
- inulin clearance (inulin is 100% filtered; not rly used in clinical practice as not practical (need constant infusion and catheter) but in books seen as gold standard)
- isotope GFR (not practical as make the person radioactive - used if really want to know kidney function e.g. if they want renal transplant)
- 24hr urine collection plus blood test
- GFR estimating equations (measure serum creatinine; reciprocal relationship between GFR and creatinine - use eqns)
Describe relationship between serum creatinine and GFR
Reciprocal
Problem with creatinine?
Creatinine is generated from breakdown of muscle and not everyone has same muscle mass; dependent on age, ethnicity gender, weight, etc
Creatinine will not be raised above normal range until what percentage of total kidney function is lost?
60%
What demographic has a naturally higher serum creatinine?
African american (they have a higher muscle mass)
What is eGFR?
Estimated GFR - this is important to remember because it is NOT a direct measure of GFR (so is vulnerable to being incorrect - if person is not average for their sex, age, race, look at the patient! i.e. someone with leg amputation will have much ess creatinine as lost all that muscle)
What is the system for assessing kidney function?
International CKD Classification System
(to remember - start from bottom - 25ml/min increments)
3 formulae to estimate GFR from serum creatinine? (dont need to memorise actual equations - just say name)
Cockcroft Gault (generally used by pharmacists for drug dosing; includes weight so not practical on population level)
MDRD 4 variable equation
CKD-EPI equation (slightly more accurate than MDRD 4)
What substances cross GBM?
Water
Electrolytes
Urea
Creatinine
What substances cross GBM but are reabsorbed in proximal tubule
Glucose
Low molecular weight proteins (α2 microglobulin)
What substances do not cross GBM?
Cells (RBC, WBC)
High molecular weight proteins (albumin, globulins)
How is the barrier function of kidneys measured? What do they measure exactly?
Urinalysis (dipstick) - blood, protein
Protein quantification - protein creatinine ratio (PCR)
Definition of CKD?
Defined by either the presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR <60ml/min/1.73m2 that is present for 3 months or longer (3 months important because can be AKI if less)
Try n name aetiologies of CKD (6) (more but these r the ones on slide)
- Diabetes (most common)
- Glomerulonephritis (and all its causes)
- Hypertension
- Systemic disease (immunological/haematological)
- Renovascular disease
- Genetic disorders e.g. polycystic kidney disease most common
4 step clinical approach to CKD
- Detection of underlying aetiology (treatment for specific disease)
- Slowing rate of renal decline (generic therapies)
- Assessment of complications related to reduced GFR (prevention and treatment)
- Preparation for renal replacement therapy
Signs and symptoms of CKD? (loads)
Appearance - pallor secondary to anaemia
Hypertension
SOB due to fluid overload
Kidneys - next card
Itch + cramps - advanced; likely due to biochemical changes = neuronal irritation
Cognitive changes
GI - anorexia, vomiting, taste disturbance
Urine output - polyuria (tubular conc ability impaired), oilguria, nocturia (impaired solute diuresis or oedema), proteinuria (frothy urine)
Haematuria (immune injury to glomerular capillary wall)
Peripheral oedema