Nephrology Flashcards
List examples of loop diuretics
furosemide, bumetanide
How do loop diuretics work?
inhibit the Na/K/Cl co transporter in the loop of henle so reduce the absorption of NaCl
What are the adverse effects of loop diuretics?
hypokalaemia, hypomagnesaemia, hypocalcaemia, hyponatraemia
hypotension
gout
List examples of thiazide diuretics
indapamide , bendroflumethiazide
How do thiazide diuretics work?
inhibit the sodium reabsorption in the distal convoluted tubule by blocked Na/Cl symporter
What are the adverse effects of thiazide diuretics?
dehydration hyponatraemia, hypokalaemia gout postural hypotension impaired glucose tolerance
List examples of potassium sparing diuretics and how they work
sodium channel blockers -> amiloride
aldosterone antagonists at the mineralocorticoid receptor at the DCT -> spironolactone
What are the adverse effects of potassium sparing diuretics?
dizziness
malaise
AKI
hyperkalaemia *
What is creatinine?
product of muscle metabolism and measure of kidney function
Where does sodium reabsorption occur?
70% - proximal tubule
25% - loop of henle
5% - DCT
Describe how blood pressure is controlled by the kidney?
- low blood pressure detected by the afferent arteriole in the kidney
- juxtaglomerular apparatus activated
- kidney secretes renin
- renin converts angiotensinogen to angiotensin 1
- ACE converts angiotensin 1 to angiotensin 2
- activates aldosterone in the adrenal glands to stimulate reabsorption of salt and water
- acts directly on blood vessels to cause vasoconstriction
- results in rise in blood pressure
List the 5 functions of the kidney
- remove waste products in the urine (e.g. drugs, toxins, products of metabolism)
- regulates water in body and blood pressure
- produces EPO for RBC production
- activates vitamin D into 1- hydroxy- vitamin D
- acid base balance (removes H+ and absorbs HCO3)
Define AKI?
acute insult in GFR from baseline, increase in creatinine +/- oliguria (<0.5 ml/kg/hr)
List the pre renal causes of AKI
= problems in other major organs causing impaired renal perfusion
renal artery stenosis heart failure sepsis ischaemia hypovolaemia e.g. vomiting, diarrhoea hypotension hepatorenal syndrome
List the intrinsic causes of AKI
= damage to the glomeruli, renal tubules or interstitium of the kidneys
glomerulonephritis acute tubular necrosis toxins and drugs interstitial nephritis IgA nephropathy tumour lysis syndrome rhabdomyolysis
List the post renal causes of AKI
= problems after the kidneys e.g. obstruction to urine coming from kidneys
INTRINSIC - stones, tumour, pyelonephritis
EXTRINSIC - BPH, tumour, retroperitoneal fibrosis
Which drugs are nephrotoxic and can cause an AKI
NSAIDS ACE-I ARBs gentamicin diuretics omeprazole anti fungals rifampicin radio iodine contrast lithium
List the risk factors for an AKI
elderly drugs and toxins IV contrast organ dysfunction e.g. liver disease, CKD, heart failure, diabetes multiple myeloma
How does AKI present?
often asymptomatic and found on bloods but can cause…
reduced urine output (<0.5 ml/kg/hr) **
nausea and vomiting
peripheral oedema
uraemia signs
What is the criteria for an AKI?
** rise in creatinine >26mmol/l in 48 hrs **
How is an AKI staged?
stage 1 =
1.5- 1.9 X baseline creatinine OR
UO <0.5 ml/kg/hr for 6-12 hours
stage 2 =
2-2.9 x baseline creatinine
UO <0.5 ml/lg/hr for >12 hours
stage 3 = 3 x baseline creatinine
UO <0.3 ml/kg/hr for >24 hrs
How is AKI diagnosed and investigated?
U&E
Creatinine elevated (normal 0.7 -1.2 mg/dL) - not best early indicator as wont change until next day so measure UO
high serum potassium
metabolic acidosis
** renal ultrasound **
do 24 hrs after AKI if dont know cause
find the cause…
urine dip and urinanalysis, FBC, ECG, blood cultures, vasculitis screen, renal biopsy
How is AKI managed?
- ABCDE - fluids
- review medication
stop nephrotoxic drugs or renally excreted drugs - monitor urine output - catheterise
- treat hyperkalaemia
- if not responding, RRT
When is RRT indicated in AKI?
uraemia no urine output and fluid overload severe resistent hyperkalaemia severe metabolic acidosis overdose of lithium
Which drugs are renally excreted and should be stopped in AKI to prevent toxicity?
metformin
lithium
digoxin
opioids e.g. codeine, tramadol
Define CKD
> 3 months of proteinuria or haematuria +/- reduction in GFR to <60ml/min/1.73m^2
What are the causes of CKD?
Diabetic nephropathy **
hypertension *
renal vascular disease*
+
glomerulonephritis (nephrotic/ nephritic) - focal segmental glomerulosclerosis, membranous nephropathy, lupus nephritis, amyloidosis
PKD
obstructive uropathy e.g. myeloma, renal tumour
what are the symptoms of CKD?
extreme fatigue ** weakness * peripheral oedema ** pruritus anorexia / weight gain / poor appetite
What are the complications of CKD?
anaemia ** (reduced EPO and iron deficiency)
renal osteodystrophy (due to decreased phosphate excretion)
CV disease
hyperkalaemia
pulmonary oedema
metabolic acidosis
secondary hyperparathyroidism
Why do pts get anaemia in CKD?
Lack of EPO produced by kidneys + iron deficiency
What are the stages of CKD?
STAGE 1 - eGFR >90
STAGE 2 - eGFR 60-89
STAGE 3a - eGFR 45-59
STAGE 3b - eGFR 30-44
STAGE 4- eGFR 15-29
STAGE 5 - eGFR <15 (start RRT)
How is the eGFR calculated?
estimate of renal function using a formula that calculates it by:
- creatinine
- age
- ethnicity
- gender
How is CKD investigated?
- serum creatinine
- renal USS
- eGFR <60
- urine albumin creatinine ratio (proteinuria) HIGH
How is CKD managed?
- find the cause -> control diabetes, statins, weight loss, smoking cessation
- manage HTN -> ACE-I with target <130/90
- manage anaemia -> epoitin alfa + ferrous sulphate (side effects of EPO = urticaria, HTN, bone aches)
- manage oedema -> loop diuretic, restrict salt
- manage renal bone disease -> vit D, calcium rich diet
- RRT if stage 5 (5-7 eGFR) or palliative care
What are the options in renal replacement therapy?
- haemodialysis
- peritoneal dialysis
- renal transplant
Who is haemodialysis most suitable for?
elderly, frail, if unsuitable for surgery or at home dialysis (most common for)
How can you maximise your kidney function before starting haemodialysis?
smoking cessation manage HTN good glycemic control in diabetics salt restriction activated VIT D supplement weight loss
how does haemodialysis work?
- blood removed from AV fistula on the arterial side
- blood enters dialyzser
- dalteparin added to prevent clots
- blood passed over semi permeable membrane against dialysis fluid - small solutes diffuse across along conc gradient and waste products diffuse out
- blood travels through venous pressure monitor and air detector
- waste products in dialysis fluid removed
- clean purified blood returned to vein in AV fistula
Where do they get access for haemodialysis?
via arterio-venous fistula **
created 8 weeks before start dialysis
What are the adverse effects of an AV fistula?
bulging veins
cold hands
gangrene
heart failure