General Flashcards
Functions of the kindey
- Filter or secrete waste/excess substances
- Retain albumin and circulating cells
- Reabsorb glucose, amino acids and bicarbonates
- Control BP, fluid status and electrolytes
- Activates 25-hydroxy vitamin D (by hydroxylating it to form 1,25 dihydroxy
vitamin D) - Synthesis erythropoietin
Define GFR
Glomerular filtration rate
Volume of fluid filtered from the glomeruli into Bowman’s space per unit time (mins)
Normal GFR
120ml/min (7.2L/h)
What % of the cardiac output does each kidney receive
20%
True or False:
eGFR can help predict creatinine generation
True
Creatinine is produced by muscles and eliminated (only) by the kidneys
Predicts Creatinine generation from age gender and race also
What is reabsorbed at proximal convoluted tubule?
Sugars
Amino acid
Bicarbonate
Main portion of Na+ (70%) and water follows
True or False:
PCTs are not vulnerable to ischaemic injury
False
ARE vulnerable to ischaemic injury, resulting in acute tubular necrosis
What part of nephron is most vulnerable to damage
Proximal Convoluted Tubule
Example of disease of PCT
Fanconi syndrome:
- proximal tubular insult
- caused by cytinosis, Wilsons and TENOFOVIR drug (used in HIV)
What can result from disease of the PCT
Glycosuria (glucose in urine)
Acidosis with failure of urine acidification
Phosphate wasting resulting in rickets/osteomalacia
Aminoaciduria (amino acid in urine)
What % of Na+ is reabsorbed by Loop of Henle
25%
and water follows
Example of a drug that can act on Loop of Henle
Loop diuretic
as alot of Na+ filtered here and water follows, if can block here can have a large effect
Example of loop diuretic
Furosemide
Which part of the LoH are sodium potassium chloride transporters more active?
Ascending loop
What % of sodium is reabsorbed in Distal Convulted Tubule
5%
What diuretics act on DCT
Thiazide diuretics e.g. Chlorothiazide
When would Juxtaglomerular apparatus release renin
Juxtaglomerular apparatus is a solute sensing organ.
If detects high solutes (e.g. Na+), it will think GFR is low so releases renin.
JXA effectively senses Blood Pressure
What part of nephron does salt handling
Collecting duct as by this point, most of salt has been reabsorbed
What ions are secreted by the collecting duct into urine
K+
H+
Name 2 hormones that act on collecting ducts
Aldosterone - increases the transcription of eNac channels which absorb Na+ in exchange for K+
Vasopressin - water is absorbed via aquaporin 2
channels
How does hyperaldosteronism lead to hypokalemic alkalosis
In hyperaldosteronism (high aldosterone) there is lots of Na+ reabsorption resulting in a negative lumen, consequently K+ and H+ rush in and this results in hypokalaemic alkalosis.
What can you give to correct hyperkalemic acidosis (like in Addisons)
Sodium Bicarbonate
Would you get alkalosis or acidosis with loop diuretics
Alkalosis
Which hormone acts on renal potassium control
Aldosterone
K+ is freely filtered and mostly reabsorbed in which parts of nephron
PCT
LoH
Effect of insulin or catecholamines on cellular K+ uptake
Increase uptake
Which K+ modifying renal medication cause hypokalemia
Loop diuretics
Thiazide diuretics
Which K+ modifying renal medication cause hyperkalemia
- Spironolactone (aldosterone antagonist)
- Amiloride (acts on eNac channels)
- ACE inhibitors (Ramipril)
- Angiotensin receptor blockers (ARB)
- Trimethoprim (acts on eNac channels but milder)
Are diuretics nephrotoxic
Diuretics are NOT NEPHROTOXIC but hypovolaemia (which they can cause e.g. loop & thiazide diuretics) IS
Loop and thiazide diuretics together are extremely powerful and effective together resulting in profound diuresis
If plasma is too concentrated, what is released by hypothalamus/posterior pituitary to dilute it
ADH (vasopressin)
What is erythropoietin
Hormone that produces haemoglobin
Produced in response to tissue hypoxia
When can erythropoietin be given
In advanced kidney disease and anaemia to help increase O2 transport
In anaemia, what is expected GFR
GFR <30
True or false:
Renal cortex acts as an oxygen sensor
True
Blood flow and oxygen are matched
What reaction occurs in kidneys in production of vitamin D
25-hydroxy vitamin D is hydroxylated to form 1,25-dihydroxy vitamin D (calcitriol)
What is effect on Calcium levels in kidney failure
Kidney cannot hydroxylate 25-hydroxy vitamin D to calcitriol. Therefore Calcium cant be absorbed from gut and so would theoretically decrease
Effects of calcitriol
- Increases Ca2+ and phosphate absorption from the gut
- Increases phosphate absorption to a lesser extent
- Suppresses parathyroid hormone (PTH)
What condition can result from calcitriol deficiency and why
Secondary Hyperparathyroidism
Low vitamin D results in low Ca2+ and phosphate resulting in increased PTH (which causes Ca2+ and phosphate leeching from bones as well as increased osteoclast activity and reduced bone)
What comprises upper urinary tract
Kidneys
Ureters
What comprises lower urinary tract
Bladder (reservoir)
Prostate gland (in men) (Uterus in women)
Urethra and urethral sphincter
What is the function of (lower) urinary tract
Micturition
To convert the continuous process of excretion (urine production) to an
intermittent, controlled volitional process
Essential features of lower urinary tract
- Low pressure and insensible storage of urine of adequate capacity
- Prevent leakage of the urine stored
- Allow rapid, low-pressure voiding at an appropriate time and place
What is the mean arterial pressure that drives filtration in the Bowman’s capsules
60-70mmHg
Why is there a progressive reduction in pressure along the nephron
Due to reabsorption as you go along
Pressure in collecting duct system is 3-10mmHg
Describe neuronal control of voiding
Pontine micturition centre stimulates excitatory control to detrusor nucleus and inhibits Onuf’s nucleus.
Signal is transmitted from spinal root S2-4 via the parasympathetic
nervous system and this results in contraction of detrusor muscles and
relaxation of the urethra.
Which spinal roots stimulate urination (voiding)
S2-S4 (parasympathetic - cholinergic)
Describe neuronal control of stopping urination (storage)
Pontine storage centre stimulates and sends inhibitory signals to
detrusor muscles and excitatory signals to Onuf’s nucleus
Signal is transmitted from spinal root T10 to L2 via the sympathetic nervous system and this results in the relaxation of the bladder and
contraction of the urethral sphincter
What is the storage of the bladder
around 500ml
Epithelium of bladder
Urothelium (transtitional)
Highly specialised stratified 3-7 cells thick
Umbrella structure that is completely impermeable so cannot reabsorb urine
Able to fold and unfold to increase volume
Why are men more likely to develop problems with retention
Have a greater voiding pressure due to them having a longer urethra.
Thus more likely to develop retention.
Why are women more likely to have problems with incontinence
Have a shorter urethra with lower resistance and thus higher flow rates
What urology complications can occur if the spinal cord is cut above S2-4?
Will only be able to urinate when the bladder is full
Descending pathway will not be able to inhibit this
Normal flow rates in men aged:
<40
40-60
>60
21ml/s (<40)
18ml/s (40-60)
13ml/s (>60)
What can reduce flow rates
Obstruction within the lower urinary tract
Detrusor underactivity
How much urine needs to be void for representative flow rate measurement
At least 125ml
What is normal PVR (Post Void Residual)
<12ml
Examples of disease that can occur from elevated PVR (Post Void Residual)
Hydronephrosis
Elevated creatinine
Example cause of high PVR (Post Void Residual)
Detrusor underactivity
Complications of BPE
Symptom progression (17-40%) Infections (0.1-12%) Stones (0.3-3.4%) Haematuria Acute retention (1-2% per year) Chronic retention Interactive obstructive uropathy (<2.5%)
What is main substance made by prostate
PSA
- liquifies semen
- glycoprotein produced by prostate cells
What zone of the prostate is the urethra in
Transitional zone (adjacent to central zone and surrounded by peripheral zone)
Which zone of prostate is most often enlarged by prostate tumour
Peripheral zone
Prostate cancer epidemiology
Fam Hx in 5-10% Mean diagnosis age is 72 Common in industrialised West Most commonly diagnosed cancer in men Lifetime risk ~15%
What type of cancer is prostate cancer
Adenocarcinoma
Where does prostate cancer spread
Spreads locally thorugh prostate capsule
Metastasises to lymph nodes and bone (sclerotic) and occasionally to lung, liver and brain
Biomarkers for prostate cancer
Tissue biopsy
Serum (blood) Prostate-Specific Antigen or Prostate-Specific Membrane Antigen (more leakage of PSA, not more produced)
Urine - PCA3 or Gene fusion products (TMPRSS2-ERG)
when would you see high PSA
Benign prostate enlargement
UTI
Prostatitis
(70% of men with high PSA do NOT have prostate cancer, 6% of men with prostate cancer will have a normal PSA)
higher PSA means higher risk of prostate cancer
>20ng/ml likely metastatic cancer (most common place is bone)
<2.5 not likely cancer
Diagnosis of prostate cancer
LUTS PSA Transrectal ultrasound scan Prostate biopsy Prostate cancer grading
Grading of prostate cancer
Gleason grading (from biopsy) Partin's nomograms - combine clinical T stage, PSA and biopsy Gleason score
Staging of prostate cancer
T stage:
T1-no palpable tumour on DRE
T2-palpable tumour, confined to prostate
T3-palpable tumour extending beyond prostate
N stage = MRI scan, CT scan, (laparoscopy)
M stage = Bone scan
Treatment of Localised Prostate cancer
Curative - surgery; radiotherapy (external beam, brachytherapy); adjuvant hormones
If not then just observation (active monitoring/survellience
Treatment of Locally advanced prostate cancer
Local control:
Surgery; radiotherapy + neoadjuvant hormone therapy
Treatment of Metastatic prostate cancer
Palliative - Hormone therapy
How could you confirm localised prostate cancer if high PSA is detected
Transrectal ultrasound
Biopsy of prostate gland
Surgery for localised prostate cancer (also do radiotherapy)
Radical prostatectomy
Open, robotic (most robotic)
What is focal therapy (prostate cancer)
High intensity ultrasound (HIFU), photodynamic therapy (TOOKAD)
Pros of radical treatment of localised prostate cancer
Curative treatment
High mortality in prostate cancer
Reduced patient anxiety
Benefits of surgery shown by longitudinal studies
Cons of radical treatment of localised prostate cancer
Disease of the elderly
Competing causes of death
30% of men with prostate cancer die OF prostate cancer
Adverse effects of treatment
Treatment of metastatic prostate cancer
Surgical castration -reduced pain due to bony metastases -prolonged survival -median survival 2.5 years Androgen deprivation therapy (GNrH analogues; LH antagonists)
Prognosis of advanced prostate cancer
80% androgen-sensitive
Castration leads to remission of advanced disease (apoptosis of cancer cells)
Median response is 2 years
What can be given if prostate cancer is castration-resistant
2nd line HRT: Abiraterone and Enzalutamide
Cytotoxic chemo
Bisphosphonates (Zoledronic acid)
Palliation
Most common site of metastasis of prostate cancer
Bone
Are majority or minority of prostate cancer cases T1c
Majority (detected on PSA testing)
Reasons for screening for prostate cancer
Commonest cancer in men – lifetime risk c. 9%
Responsible for 10,000 deaths per annum in UK.
4th most common cause of cancer death.
3% of men will die of prostate cancer.
Reasons against screening for prostate cancer
Uncertain natural history
Overtreatment
Morbidity of treatment
Benefits of PSA testing
Early diagnosis of localised disease (cure)
Early treatment of advanced disease (effective palliation)
Risks of PSA testing
Over-diagnosis of insignificant disease
Harm caused by investigation/ treatment
Prevention of prostate cancer
Dietary
5 alpha-reductase inhibitors