Case 22 - Chronic Kidney Disease Flashcards
Why is best to do a mid stream urine (MSU) sample in the morning when looking for protein?
Periods of prolonged standing can cause orthostatic proteinuria
What could protein in urine indicate?
Some kind of kidney disease
- glomerular diseases (nephritic/nephrotic syndrome)
- chronic kidney disease
- tubulointerstitial disease
- UTI
- fever
It can also occur after physical exercise, and in pregnancy
What could blood in urine indicate?
Infection
Kidney or bladder cancer
Kidney disease
What are the normal levels of protein that are excreted in urine?
Up to 150mg/day of uromodulin (tamm-horsfall glycoprotein)
Up to 30mg/day of albumin
Define chronic kidney disease (CKD)?
Impaired renal function for >3 months
GFR <60 for greater than 3 months
What is the GFR level for end stage renal failure (ESRF)?
<15mL/min
What are the common causes for CKD?
Diabetes (type II) Glomerulonephritis - commonly IgA nephropathy Hypertension Polycystic kidney disease Renovascular disease Pyelonephritis
How is CKD staged?
On GFR: G1<90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, G5 <15
On Albumin/Creatine Ratio: A1 <30, A2 30-300, A3 >300
At what CKD stage do symptoms start to occur?
Stage 4
What blood tests are done to assess renal function?
FBC - assess Hb ESR U&E Glucose Calcium Phosphate PTH
What happens to the size of the kidneys in CKD?
How can this be assessed?
Shrink in size (usually <9cm in CKD)
Using an ultrasound
What are the systemic complications of CKD?
Renal anaemia Hyperkalaemia Hypertension Renal bone disease Cardiovascular complications Odema Urea toxicity
How does CKD lead to renal anaemia?
The kidney is responsible for producing erythropoietin, which in turn stimulates RBC production
If kidney is damaged there is less EPO produced therefore less RBCs produced
This leads to normochromic, normocytic anaemia
How is renal anaemia treated?
Oral or IV iron
Aim for target ferritin of >200
Recombinant human erythropoietin (darbepoetin)
How does CKD lead to hyperkalaemia?
The kidney is involved in electrolyte balance
When damaged it cannot excrete K+
This can lead to cardiac arrhythmias
How is hyperkalaemia treated in CKD?
Avoid high potassium foods in diet
Reduce ACEi dosage - ACEi block the production of aldosterone (aldosterone helps in K+ excretion)
How does CKD lead to hypertension?
Less fluid is filtered by the kidneys
It is tricked into thinking BP is raised - activates RAAS system
This increases BP
How does CKD lead to renal bone disease?
Kidneys are responsible for activating vitamin D which then helps to absorb calcium from the diet
Less activated VitD means less Ca absorbed causing hypocalcaemia
Hypocalcaemia causes PTH release
PTH activates osteoclasts to break down bone and release calcium
How is renal bone disease treated?
Vit D analogues e.g, alfacalcidol
Restrict phosphate in diet - this helps to activate PTH further
Parathyroidectomy - if PTH levels are too high and unable to be controlled
Cinacalcet - drug used to treat secondary hyperparathyroidism
How does CKD lead to metabolic acidosis?
The kidneys cannot reabsorb bicarbonate as well
Therefore too much bicarbonate is lost
This leads to metabolic acidosis
How is metabolic acidosis treated in CKD?
Sodium bicarbonate supplements
Why do you get oedema in CKD?
How do you treat it?
Due to build up of fluid as kidney isn’t filtering as well
Treat with diuretics e.g furosemide
What are the effects of angiotensin II?
Causes vasoconstriction of the efferent blood vessels in kidneys - causing increased glomerular pressure
Acts on the adrenal gland to release aldosterone - aldosterone then acts on the kidneys to retain Na+ and water and excrete K+
Acts on the pituitary gland causing ADH secretion, which in turn causes H20 reabsoption in the kidneys
When should you stop ACEi or ARBs?
AKI - as these drugs inhibit the RAAS system, which is responsible for maintaining GFR
If there is a large increase in creatinine following initiation of treatment (acceptable levels are 20-25% rise)
During pregnancy
