Renal Failure Flashcards
ways to measure excretory renal function 4
gfr= glomerular filtration rate
- plasma/ serum creatinine
- estimated GFR: MDRD formula (sex, age, race, creatinine)
- creatinine clearance
- isotope GFR (usually Cr15 EDTA)
problems with serum/plasma creatinine 4
- related to muscle mass (more muscle, more creatinine so normal has big range)
- may not be elevated above ‘normal’ until 50% GFR lost
- changes within normal range are significant
- artefacts: muscle damage, drugs
what kind of creatine measurements are most useful
serial
write modified MDRD formula
eGFR (ml/min/1.73m2)= 2.107x serum creatinine (umol/l)-1.154 x age -0.203
normal GFR range
100-200
define acute kidney injury AKI and outcome
rapid loss of renal excretory function (over hours or days rather than weeks)
reversible if underlying condition is treated
define chronic kidney disease CKD
slowly progressive loss of excretory renal function. original cause often unknown, usually irreversible (management aimed at slowing progression)
3 causes of AKI
- pre-renal: problem in blood supply to kidney (thrombosis, dec bp)
- intrarenal: direct damage to kidneys due to inflammation/ toxins/ drugs/ infection/ reduced blood supply
- post-renal: obstruction to urine flow eg prostate enlargement, kidney stones, bladder, tumour, injury
4 causes of pre renal AKI
- salt and water depletion (diarrhoea, vomiting, diuretics, fever, poor fluid intake)
- haemorrhage (esp gastrointestinal)
- hypotension (heart failure, drugs, sepsis, shock)
- renovascular disease
types of renal AKI and % 3
85% tubular necrosis (mostly due to pre renal factors eg low bp)
10% interstitial nephritis
5% glomerulonephritis
how to diagnose kidney disease
- urine dipstick
- renal biopsy (interstitial nephritis, acute glomerulonephritis
8 causes of toxic AKI
- antibiotics eg aminoglycosides, amphotericin
- radiographic contrast media (inc non-ionic)
- chemotherapy agents esp cis-platinum
- rhabdomyolysis
- intravascular haemolysis
- tumour lysis
- solvents (inc ethylene glycol, carbon tetrachloride)
- hepatorenal syndrome
3 common causes of post renal AKI
- obstruction to outflow from both kidneys or to outflow from a single functional kidney esp prostate in males, cervix in females
- retroperitoneal fibrosis, neurogenic bladder
- intra-renal obstruction eg crystals or casts (esp myeloma)
what does prognosis of post renal AKI depend on 2
- underlying condition
- duration of obstruction
causes of chronic kidney disorder 5
- diabetic neuropathy MOST COMMON
- genetic causes (esp polycystic kidney disease) 10%
- vascular disease
- chronic glomerulonephritis
- chronic urinary outflow obstruction
classification system of chronic kidney disease
5 stage according to eGFR
1: normal kidney function with some other evidence of kidney disease
5: eGFR less than 10-15 ml/min ie need for renal replacement
consequences of renal failure 7
-accumulation of 6: K+, urea, creatinine, H+, water, PO4
-deficiency of 2: erythropoitin–> anaemia
1 alpha vitamin D3 –> hypocalcaemia, hyper parathyroid hormone, bone disease
-delayed drug excretion
-pulmonary oedema
-xerostomia
-uraemic stomatitis (white/ grey on FOM)
-brown tumour
outcome of K+ accumulation
changes polarisation of cells –> large T waves –> cardiac arrythmias –> sudden death
how to control potassium
diet (eg less bananas)
explain renal bone disease
less calcium –> less vit D activation –> non calcified osteoid –> bone resorption
4 tx for renal replacement therapy
- dialysis/ transplantation
- erythropoietin
- 1 alpha vitamin D
- sodium bicarbonate
normal blood Hb levels
130-150g/l
how does a haemodyaliser work
contains small plastic ‘capillaries’ surrounded by dialysis fluid for filtration
explain arterial-venous fistula
sew artery to vein –> blood flows in to vein –> dilates vein –> can put needles in to vein for dialysis
why are anticoagulants used in dialysis and examples 3
stops blood clotting during dialysis
- heparin for dialysis
- warfarin for access patency
- aspirin
what does CAPD stand for and how does it work
Continuous Ambulatory Peritoneal Dialysis
needle and dialysis in to peritoneum (space between organs) –> fluid exchanged over peritoneal membrane continuously/ 4 times per day
6 general consequences of immunosuppression
- infection (correlation with corticosteroid dosage)
- viral transmission with transplant esp CMV
- malignancy (esp viral eg lymphoma, skin, cervix. UV exposure and skin type important)
- hypertension
- dyslipidaemia
- osteopaenia
2 main causes of gingival hyperplasia
- cyclosporin (immunosuppression)
- calcium blockers (dipines)
5 adverse effects of cyclosporin
- nephrotoxicity
- tremor
- hirtuism
- gingival hypertrophy (worsened by nifedipine)
- interactions (esp macrolides, diltiazem)
4 important drug interactions
- cyclosporin and macrolides (erythromycin, clarithromycin)
- cyclosporin and diltiazem
- cyclosporin and enzyme inhibitors
- azatioprine and allopurinol
5 considerations for dental care after renal transplantation
- good OH essential
- gingival hypertrophy (cyclosporin, nifedipine)
- inc susceptibility to infection
- antibiotic prophylaxis
- drug interactions esp erythromycin etc
6 normal functions of kidneys
- excretion of salt/ water/ waste products of metabolism (via urine)
- regulation of acid-base (H+) in tubules
- regulation of blood pressure (with renin)
- production of erythropoetin (stimulates RBCs)
- activation of vit D (1 alpha hydroxylase)
- excrete water soluble drugs/ metabolites
order blood moves around kidney
afferent arteriole –> glomerulus -> vasa recta
order of nephron system kidneys
bowmans capsule –> proximal convoluted tubule –>loop of henle –> distal convoluted tubule –> collecting duct
increase in serum creatinine in AKI stage
1
2
3
1: 1.5-2
2: 2-3
3: >3 or >354umol/L with acute increase of >44umol/L
most common known cause of kidney failure in pts starting renal replacement therapy in UK
diabetes
% of people in england with diabetes
7.4%
proportion of people with diabetes who have kidney disease
18%-30%
% of patients having tx/ dialysis whose kidney disease was due to diabetes
14%
categories of GFR
G1: normal/ high GFR G2:mildly decreased G3a: mild-mod decreased G3b: mod-severely decreased G4: severely decreased G5: kidney failure
what is
a. normal GFR
b/ GFR in kidney failure
a. normal GFR: >90ml/min/1.73m2
b. GFR in kidney failure:
presentation/ symptoms of chronic kidney disease
often asymptomatic until CKD4/5 (GFR
3 lab changes of CKD
anaemia
disordered bone mineral metabolism
acidosis
AKI/ CKD consequeneces:
a. accumulation of (6)
b. deficiency of (2) and consequences
c. delayed (1)
a. accumulation of (6): K+, urea, creatinine, H+, water, PO43-
b. deficiency of (2) and consequences: erythropoietin –> anaemia. 1alpha vit D3 –> hypocalcaemia, hyperPTH, bone disease
c. delayed (1): drug excretion
what does uraemic stomatitis look like
white-grey pseudomembranous lesion on tongue and FOM
