RENAL Flashcards
pre-renal causes of AKI
reduced renal perfusion (fluid depletion/dehydration, sepsis, renal artery obstruction, reduced cardiac output)
post-renal causes of AKI
stones, tumours, BPH, obstruction in bladder/ureters/urethra
intra-renal causes of AKI
acute tubular necrosis, interstitial nephritis, vasculitis, GN, renal artery/vein obstruction
sings of AKI
hyperkalaemia/hypokalaemia raised creatinine raised urea acidosis reduced/no urine output
examples of fluid shift
ascites, effusions, capillary leak states (sepsis/burns)
causes of negative fluid balance
decreased input
increased output
fluid shift
renin is secreted in response to what
reduction in glomerular filtration rate
how is a reduction in the GFR detected
stretch receptors in the macula dense cells of the juxtaglomerular apparatus are stimulated
action of renin
angiotensinogen to angiotensin I
which enzyme converts angiotensin I to angiotensin II
ACE
what stimulates release of aldosterone
renin
effect of aldosterone release
increased sodium reabsorption in the DCT
increased excretion of potassium
what is renal artery stenosis
narrowing of the renal artery lumen
chronic elevation of angiotensin II results in what
cardiac and vascular hypertrophy
what does atrial natriuretic factor detect
atrial filling
what stimulates release of ANP
increased volume (increased atrial filling)
what does ANP do
inhibits sodium reabsorption in the DCT (opposes aldosterone)
mechanism of action of ACEIs
inhibits the formation of angiotensin II leading t vasodilatation
examples of ACEI
rampiril, lisonopril
mechanism of action of ARBs
block angiotensin II receptors on blood vessels/tissues
examples of ARBs
losartan
actions of ACEIs/ARBs on the CV system
dilate arteries (reduce arterial pressure, preload and after load) down regulate sympathetic adrenergic activity promote renal excretion of Na and water (reduces blood volume, venous pressure and arterial pressure) inhibit cardiac and vascular remodelling associated with HTN, HF, MI
mechanism of action of a1 receptor blockers
block a1 adrenoceptors in the bladder and prostate, relaxing smooth muscle and reaching resistance to urinary flow and damage to kidneys from downstream obstruction
example of a1 receptor blocker
tamulosin
nephrotoxic side effects of gentamicin
acute tubular necrosis
nephrotoxic side effects of vancomycin
acute interstitial nephritis
nephrotoxic side effects of ACEIs
reversible acute renal failure (HTN/CHF)
nephrotoxic side effects of diuretics
reduced GFR
hypokalaemia nephropathy
polyuria
interstitial nephritis
nephrotoxic side effects of NSAIDs
AKI caused by sodium and water retention, reducing renal blood flow and direct kidney injury
what is the ‘triple whammy’ effect
the significant increase in harm that may result from the combined use of NSAIDs, ACEIs/ARBs and diuretics in high-risk individuals.
mechanism of action of the ‘triple whammy’ effect
NSAIDs constrict the blood flow into the glomerulus via the afferent arteriole by inhibiting vasodilator prostaglandins
ACEIs/ARBs decrease angiotensin II level/action, leading to reduced GFR by dilating the efferent arteriole
diuretics induced dehydration and blood volume reduction leading to insufficient renal haemodynamics and failure to maintain GFR
what is the definition of CKD
gradual loss of kidney function due to abnormal function or structure
what is the best measure of overall kidney function
GFR
what factors are taken into account when calculating eGFR
serum creatinine, age, gender, race
what advice should be given to patients before eGFR testing
avoid eating meat for 12 hours before
GFR for CKD stage 1
> 90
GFR for CKD stage 2
60-89
GFR for CKD stage 3
30-59
GFR for CKD stage 4
15-29
GFR for CKD stage 5
<15
effect of ageing on GFR
decreases with age
NICE guidance for patients over 70 with reduced GFR
stable GFR >45 is unlikely to be associated with CKD-related complications
GFR for CKD stage 3A and 3B
3A 45-59
3B 30-44
what does the suffix P mean in relation to CKD staging
proteinuria
common causes of CKD
diabetes, GN, pyelonephritis, renal vascular disease, polycystic kidney disease, hypertension
patients at higher risk of developing CKD
diabetics hypertension CVD structural renal tract disease multi system disease with potential for renal involvement (eg SLE) patients with a FH of CKD stage 5
common nephrotoxic drugs
NSAIDs
lithium
diuretics
ACEIs
lifestyle measures for management of CKD 1,2,3
smoking cessation weight loss regular exercise and a healthy diet sensible alcohol consumption low salt
what is classed as progressive CKD
decline of more than 5 ml/min/1.73m^2 over 1 year OR more than 10 ml/min/1.73m^2 over 5 years
how often should BP be measured in patients with CKD
at least once a year
BP target s for patients with CKD
120-139 mmHg systolic and <90 mmHg diastolic UNLESS proteinuria/diabetic with microalbuminuria 120-129 mmHg systolic and <80 mmHg diastolic
recommended lab testing for CKD stage 1/2
eGFR, PCR/ACR yearly
recommended lab testing for CKD stage 3
eGFR, PCR/ACR, Hb, K+, Ca2+, phosphate 6 monthly (12 monthly if stable)
recommended lab testing for CKD stage 4
eGFR, PCR/ACR, Hb, K+, Ca2+, phosphate, HCO3, PTH 3 monthly
recommended lab testing for CKD stage 5
eGFR, PCR/ACR, Hb, K+, Ca2+, phosphate, HCO3, PTH 6 weekly
first line management of HTN (protein/microalbuminuria) in CKD
ACEIs (or ARBs)
when should ACEIs be reduced in dose or stopped
if there is more than a 25% fall in eGFR from the pre-ACEI value
indications for referral to nephrologist in CKD
acute renal failure
malignant hypertension
hyperkalaemia (>7 mmol/L)
nephrotic syndrome
what is renal bone disease
CKD is associated with elevated PTH, in association with low Ca and high phosphate, and inadequate renal vitamin D production
what type of anaemia is commonly associated with CKD
normochromic normocytic anaemia
what causes anaemia in CKD
inadequate production of erythropoietin
risk factors for urinary incontinence
female sex pregnancy vaginal delivery pelvic surgery pelvic organ prolapse raised IAP (chronic constipation, lung disease) obesity menopause caffeine
incontinence may be caused by
neurological dysfunction
abnormalities of detrusor function
abnormalities of the sphincter apparatus (including surrounding pelvic floor muscles and tissue)
anatomical abnormalities
four main types of incontinence
stress
urge
mixed
overflow
what is stress incontinence
leakage of urine caused by effort or exertion or on coughing/sneezing
causes of stress incontinence
problem with the sphincter apparatus
neurological problem
what causes urge incontinence
overactivity of the detrusor muscle
what is urge incontinence
uncontrollable leaking of urine preceded by or accompanied by a sudden urge to void
what is overflow incontinence
large volume chronic retention due to bladder outflow obstruction resulting in leaking when the bladder can hold no more urine
what causes overflow incontinence
prostatic enlargement
bladder obstruction
complications of overflow incontinence
associated with increased risk of renal failure due to vesicouteric incompetence and hydrostatic pressure on the renal system
triggers for stress incontinence
coughing, sneezing, exercise, lifting or rising from sitting
tiggers for urge incontinence
running taps
cold weather
examination of incontinence
abdominal exam
PR (men)
pelvic (women)
neurological
investigations of incontinence
bladder diary for three days
urine dip
bladder scan
management of stress incontinence
pelvic floor exercises
recommend weight loss
management of urge incontinence
bladder training (6 weeks) oxybutynin if ineffective intravaginal oestrogen if atrophy recommend decreased caffeine intake and weight loss
urgent referral criteria for incontinence
non-visible haematuria if over 50
visible haematuria in any age group
recurrent/persistent UTI with non-visible haematuria if over 40
suspected levin mass
routine referral for incontinence
prolapse of the vagina that is symptomatic and visible
patients with a palpable bladder after voidinh/high post-void volume
consider referral for incontinence
persistent bladder/urethral pain
associated faecal incontinence
suspected neurological disease
voiding difficulties
suspected fistula (continuous incontinence)
previous surgery to correct incontinence
previous pelvic irradiation/cancer surgery
surgical management of stress incontinence
mid-urethral tapes such as tension/free vaginal tapes or transobturator tapes
secondary care management of urge incontinence
botox injections
sacral nerve stimulator
management of post-prostatectomy incontinence
pelvic floor exercises
management of outflow incontinence
alpha blockers
5a-reductase inhibitors
action of 5a-reductase inhibitors
inhibit the enzyme responsible for converting testosterone to dihydrotestosterone (important in development of BPH)
slows progression of BPH
mechanism of action of a-blockers
relax the smooth muscle of the bladder neck, aiding non-obstructive voiding
reversible causes of UI in older people
Delerium
Infection
Atrophic vaginitis
Pharmaceuticals (opiates, calcium antagonists, anticholinergics)
Physiological problems (anxiety, depression)
Excess urine output (high fluid intake, diuretics)
Reduced mobility
Stool impaction
what are LUTS
lower urinary tract symptoms
symptoms of BPH
urinary frequency nocturia urgency poor flow incomplete bladder emptying
differential diagnosis of BPH
bladder neck obstruction urethral stricture carcinoma in situ of the bladder Parkinson's disease cauda equina lesions nocturnal polyuria DM
examination of BPH
PR
likelihood of prostate cancer with a raised PSA
20-25%
investigation of BPH
PSA
uroflowmetry
measurement of post-ovoidal residual volume
upper urinary tract
kidneys
ureters
lower urinary tract
bladder
urethra
what are the 5 layers anterior to the kidney
renal capsule perinephric fat renal (deep) fascia paranephric fat visceral peritoneum
muscles of the posterior abdominal wall
psoas major
quadrates lumborum
vertebral level of the kidneys
left kidney T12-L2
right kidney L1-L3
what is the clinical relevance of the hepatorenal recess
the most dependent part of the greater sac - fluid more likely to collect there in the supine position
the right kidney is posterior to
liver
duodenum
ascending colon
right colic flexure
the left kidney is posterior to
stomach
tail of pancreas
hilum of spleen
splenic vessels
lymph from the kidneys drains where
lumbar nodes
lymph from the ureters drains where
lumbar and iliac nodes
what is the ureteric blood supply
branches from; renal artery abdominal aorta common iliac internal iliac vesical artery
parts of a nephron
glomerulus bowman's capsule PCT loop of henle DCT collecting duct
how does urine drain from the kidney
collecting ducts minor calyx major calyx renal pelvis ureter
anatomical sites of ureteric constriction
pelviureteric junction
crossing of the common iliac
vesicoureteric junction
what is hydronephrosis
urine back pressure into the calyces compressed the nephrons within the medullary pyramids leading to renal failure
where is the perineum
between the pelvic floor and skin
what makes up the three points of the trigone
2 ureteric orifices
internal urethral orifice
which muscle makes up the majority of the bladder wall
detrusor muscle
2 routes for catheterisation
urethral
suprapubic
what is contained in the spermatic cord
testicular artery testicular vein vas deferencs lymphatic vessels nerves
the testis sit within a sac called the
tunic vaginalis
what is a hyprocoele
excess fluid in the tunica vaginalis
what are the three cylinders of erectile tissue in the penis called
right and left corpus cavernosum
corpus spongiosum
blood supply to the penis
deep arteries of the penis (branches of the internal pudendal artery from internal iliac)
blood supply to the scrotum
internal pudendal and branches from the external iliac
lymph form the scrotum and penis is drained where
superficial inguinal nodes
lymph from the testis drains where
to the lumbar nodes
what are the specialised epithelium cells that overlie the glomerular capillaries called
podocytes
which two cell layers separate the blood from the glomerular filtrate
capillary endothelium
podocytes
what lies between the capillary endothelium and the podocyte epithelium
basal lamina
what is the function of the mesangial cells
support
removal of debris
what is the thick ascending limb of the loop of henle lined by
simple cuboidal epithelial cells with abundant mitochondria
extensive brush border
cells of the juxtaglomerular apparatus
macula densa
juxtaglomerular cells
extraglomerular mesangial cells (or laces cells)
the majority of the conducting parts of the urinary tract are lined by
transitional epithelium (urothelium)
what cells make up the transitional epithelium
umbrella (surface) cells
2 ways the transitional epithelium is specialised to its function
the variability in thickness of cells represents different states of distension
the apical surface of cells at the surface have a thickened membrane to provide a highly impermeable barrier
types of epithelium in the female urethra
transitional
stratified squamous near termination
types of epithelium in the male urethra
transitional
stratified columnar after prostate through the penis
stratified squamous at the tip of the penis
what is osmolarity
concentration of osmotically active particles present in a solution
which two factors influence the osmolarity of a solution
molar concentration
number of osmotically active particles present
what is osmolarity of body fluids
300 mosmol/L
what is the tonicity of a solution
the effect a solution has on cell volume
2 major fluid compartments
ICF
ECF
the main ions in the ECF are
Na
Cl
HCO3
the main ions in the ICF are
K
Mg
-ve charge proteins
juxtamedullary vs cortical nephrons
juxtamedullary are less numerous, travel deeper into the medulla and have a vasa recta that follows the loop of Henle
what are the three renal processes required to produce and concentrate urine
glomerular filtration
tubular reabsorption
tubular secretion
rate of excretion =
rate of filtration + rate of secretion - rate of reabsorption
rate of filtration =
concentration in plasma x GFR
rate of excretion =
concentration in urine x urine flow rate
rate of reabsorption =
rate of filtration - rate of excretion
rate of secretion =
rate of excretion - rate of filtration
how do sympathetic nerves leave the spinal cord
cranial nerves
spinal nerves T1-L2 (thoracolumbar outflow)
what do sympathetic nerves innervate
smooth muscle
glands
how do sympathetic nerves get from the CNS to the kidneys, ureters and bladder
leave the spinal cord between T10 and L2
enter sympathetic chains but do not synapse
leave the sympathetic chains within abdominopelvic splanchnic nerves
synapse at the abdominal sympathetic ganglia located around the abdominal aorta
follow arteries to the organs they innervate
how do parasympathetic nerves leave the CNS
within 4 cranial nerves (II, VII, IX, X) and sacral spinal nerves
(craniosacral outflow)
how do parasympathetic nerve fibres get from the CNS to the kidney, ureters and bladder
kidneys and ureters - CNX
bladder - pelvic splanchnic nerves
what types of nerve innervate the kidneys, ureters and bladder
sympathetic
parasympathetic
visceral afferents
(distal urethra and sphincter somatic motor)
where is pain from the kidney normally felt
loin
where is renal colic normally felt
loin to groin
where is pain from the bladder felt
suprapubic
where is pain from the perineal urethra felt
perineum (localised)
how do visceral afferent get from the kidneys to the CNS
run alongside sympathetic fibres back to the spinal cord
enter between T11 and L1
how do visceral afferent nerve fibres get from the ureters to the CNS
run alongside sympathetic fibres
enter between T11 and L2
how do visceral afferent nerve fibres get from the bladder to the CNS
from the superior bladder (touching peritoneum)
- run alongside sympathetic fibres back to spinal cord
- enter between T11-L2
from the rest of the bladder (not touching peritoneum)
- run alongside parasympathetic nerve fibres back to spinal cord levels S2-4
how do visceral afferent and somatic sensory nerve fibres get from the urethra to the CNS
visceral afferents
- alongside parasympathetic nerve fibres to spinal cord levels S2-4
somatic sensory
- within the pudendal nerve to spinal cord level S2-4
how do pain fibres get from the testis to the CNS
visceral afferents run alongside sympathetic fibres back to the spinal cord levels T10-11
due to its close relationship to the scrotal wall, pain from testis can also present localised to the scrotum and/or groin
which spinal cord levels are most important in control of micturition
S2-4
femoral nerve innervates which compartment of the thigh
anterior
obturator nerve innervates which compartment of the thigh
medial
sciatic nerve innervates which compartment of the thigh
posterior
superficial fibular innervates which compartment of the leg
lateral
deep fibular innervates which compartment of the leg
anterior
tibial nerve supplies which compartment of the leg
posterior
three physical barriers to glomerular filtration
glomerular capillary endothelium basement membrane (basal lamina) slit processes of podocytes in glomerular epithelium
does the glomerular basement membrane have a charge
negatively charged
forces that comprise the net filtration pressure
glomerular capillary blood pressure
bowman’s capsule hydrostatic pressure
capillary oncotic pressure
bowman’s capsule onctoic pressure
what is normal GFR
125 ml/min
what is the major determinant of GFR
glomerular capillary blood pressure
extrinsic control of GFR
sympathetic control via baroreceptor reflex
intrinsic control of GFR
myogenic mechanism
tubuloglomerular feedback mechanism
effect of vasoconstriction of the afferent arteriole on GFR
decreases blood flow > decreased net filtration pressure > decreases GFR
effect of vasodilation of the afferent arteriole on GFR
increases blood flow > increases net filtration pressure > increases GFR
do changes in systemic arterial pressure result in changes in GFR
not necessarily
RBF and GFR are protected from changes in MABP over wide ranges
GFR stays quite constant unless at extremes
myogenic auto regulation of GFR
if vascular smooth muscle is stretched (increased BP), it contracts thus constricting the arteriole
tubuloglomerular feedback auto regulation of GFR
involved the juxtaglomerular apparatus
if GFR rises, more NaCl flows through the tubule leading to constriction of afferent arterioles
effect of an increased bowman’s capsule fluid pressure on GFR
decreased GFR
effect of increased capillary oncotic pressure on GFR
decreased GFR
effect of decreased capillary oncotic pressure on GFR
increased GFR
pressures opposing/favouring filtration
favouring - glomerular capillary fluid pressure, bowman’s caplsue oncotic pressure
opposing - bowman’s capsule fluid pressure, capillary oncotic pressure
name a substance that is filtered, completely reabsorbed and not secreted
glucose
name a substance that is filtered, not reabsorbed and not secreted
inulin
name a substance that is filtered, partly reabsorbed and not secreted
urea
name a substance that is filtered, secreted and not reabsorbed
H+
clearance < GFR
substance is reabsorbed
clearance = GFR
substance is neither reabsorbed nor secreted
clearance > GFR
substance is secreted
why is PAH used to calculate renal plasma flow
it if filtered, secreted and not reabsorbed ie it is completely cleared from the plasma
a GFR marker should be…
filtered freely, not secreted or reabsorbed
an RFP marker should be…
filtered and completely secreted
what is the filtration fraction
the fraction of plasma flowing through the glomeruli that is filtered into the tubules
substances reabsorbed in the PT
sugars amino acids phosphate sulphate lactate salt
substances secreted in the PT
H+ neurotransmitters bile pigments uric acid drugs (eg penicillin) toxins
how is sodium transported out of tubular cells
NaK pump
one sodium out, one potassium in
how is glucose transported into tubular cells
sodium dependent glucose transporter
how is glucose transported out of the tubular cells
facilitated diffusion
what is the transport maximum
the maximum amount of a substance that can be transported at one time
transport processes for reabsorption/secretion are saturated
what is the renal threshold for plasma glucose
10-12 mmol/L
what is countercurrent flow
opposing flow in two limbs
what is reabsorbed in the AL of the loop go henle
Na
Cl
WATER IMPERMEABLE
what is reabsorbed in the DL
no NaCl
HIGHLY PERMEABLE TO WATER
what is the purpose of countercurrent multiplication
to concentrate the medullary interstitial fluid
