Urology Flashcards
How do we calculate osmolarity?
Osmolarity = Concentration x No. of dissociated particles
= Osm/L OR mOsm/L
Describe the steps for positive/negative water balance
Positive:
High water intake –> ECF increases, plasma osmolality decreases, sodium concentration increases –> Hypoosmotic urine production –> Osmolarity normalises
Vise versa
What happens to urea after being filtered through Bowman’s capsule and how does vasopressin affect this?
Vasopressin boosts UTA1 and UTA3 numbers which is located in the collecting duct. Urea leaves collecting duct –> increases interstitial osmolarity. UTA2 receptor along thin descending limb leads to uptake of urea. UT B1 uptakes urea back into blood
Factors influencing ADH production and release (2 broad categories)
Stimulatory:
Nicotine
Hypovolaemia
Hypotension
High plasma osmolarity
Angiotensin II
Inhibitory:
Ethanol
ANP
Hypervolaemia
Hypertension
Low plasma osmolarity
How does Atrial natriuretic peptide affect ADH production?
Inhibitory
Describe how ADH works at the collecting duct
Binds to V2 receptor on basolatoral membrane –> cyclic AMP –> protein kinase A –> upregulation of AQP2 & 3 –> increased water reabsorption
At a cellular level how is NaCl reabsorbed in thick ascending limb?
What does ADH do in terms of Na+ reabsorption?
Thick ascending limb: ↑Na+ - K+ - 2Cl- symporter
Distal convoluted tubule: ↑Na+ - Cl- symporter
Collecting duct: ↑Na+ channel
TReatment for nephrogenic diabetes insipidus
Very hard to treat - try diuretics + NSAIDS
Symptom of inappropriate ADH secretion (SIADH) clinical features and treatment
Hyperosmolar urine
Low urine volume
Hypoosmolar blood
Low plasma osmolarity
Treat the cause
What does the Henderson-Hasselbalch equation help us study?
What part of the brain centrally controls regulation of sodium intake?
Lateral parabrachial nucleus at the junction of the midbrain and pons
What does the parabrachial nucleus do under normal conditions of euvolemia (normal sodium levels)
A set of cells in parabrachial nucleus that respond to serotonin, glutamate suppress basal Na+ intake
What happens under conditions of Na+ deprivation?
- There is an increased appetite for Na+
- This is driven by GABA and opioids
How is GFR linked to renal plasma flow rate and blood pressure?
- RPF rate is proportional to mean arterial pressure
- Approx 20% of renal plasma enters tubular system so GFR = RPF * 0.2 therefore GFR is also proportional to mean arterial pressure
What happens at a certain threshold of high blood pressure to GFR and RPF?
It plateus; dont want to excrete excess salt while exercising etc
Describe the nephron’s system to limit sodium loss through kidney excretion
HIgh sodium in filtrate so high sodium in DCT
detected by the macula densa in juxtaglomerlular apparatus.
Increased NaCl means greater NaCL absorbption by macula densa triple transport.
Releases adenosine which has two functions:
1. Acute reduction of renin production
2. detected by extramesangial cells which interact with afferent arteriole leading to vasodilation. Reduced blood flow so lower perfusion pressure so reduced eGFR
Describe the various systems in the nephron to increase Na+ reabsorption/retention
Sympathetic activity (3)
- contracts SMC of afferent arteriole
- stimulates Na+ uptake of PCT cells
- stimulates JGA cells to produce renin which leads to Ang II production
- Ang II (3)
- stimulates PCT cells to take up Na+
- stimulates adrenal glands to produce aldosterone which stimulates Na+ uptake in distal part of DCT and collecting duct
- Vasoconstriction
Low tubular Na+ itself will stimulate production of renin from JGA and therefore Ang II
Now describe the system in the nephron for decreasing Na+ reabsorption
Atrial natriuretic peptide:
- Acts as vasodilator
- Reduces Na+ uptake in PCT, DCT and collecting duct
- Suppresses production of renin by JGA
How does the body react when we have low sodium levels?
1) Low sodium means lower blood pressure and low fluid volume
2) This increases beta1-sympathetic activity which stimulates afferent arteriole SMC to contract and reduce glomerular filtration pressure
3) Stimulates renin production which cleaves angiotensinogen into Ang I which is cleaved by ACE into Ang II
4) Ang II stimulates zona glomerulosa of adrenal gland to release aldosterone which increases Na+ reabsorption
5) Ang II also promotes vasoconstriction and Na+ reabsorption
6) This all reabsorbs more Na+ and reduces water output
How does the body react when we have high sodium levels?
) High sodium means higher fluid volume meaning higher blood pressure
2) This suppresses beta1-sympathetic activity and causes production of ANP
3) This reduces renin which reduces Ang I which reduces Ang II which reduces aldosterone
4) This promotes vasodilation and decreases Na+ and water reabsorption
What stimulates aldosterone release?
Ang II promotes synthesis of aldosterone synthase which causes last 2 enzymatic steps in production of aldosterone from cholesterol
- Also released when there’s a decrease in blood pressure via baroreceptors
What does aldosterone do to the kidneys?
- Stimulates Na+ reabsorption (35g per day)
- Increased K+ secretion
- Increased H+ secretion
What kind of renal cancers are there?
- 85% are renal cell carcinomas (adenocarcinomas)
- 10% are transitional cell carcinomas
- 5% are sarcoma/Wilms tumour/other types
Common causes of Renal Cancer
- Smoking
-Obesity - Hypertension
- Renal failure and dialysis
- Genetic predisposition with Von Hippel-Lindau syndrome (50% of individuals will develop RCC)
-Having hepatitis C - Abstestos
Clinical features of renal cancer and explanation
and what is the most common
- Mass - if there’s a mass there would be anaemia, weight loss, hypercalcaemia
- If no mass
- Loin pain
- Haemorrhage
- Varicocele- why?- left sided renal tumours
- You get compression of renal vein due to tumour thrombus
-Metastatic disease symptoms like bone pain, haemoptysis, shortness of breath
- Most common= painless haematuria
Investigation for kidney cancer following Painless visible Haematuria
Flexible cystoscopy
CT urogram
Renal function
Investigation for kidney cancer following Persistent non visible haematuria
Flexible cystoscopy
US KUB
Suspected kidney cancer Investigation
CT renal triple phase
- staging CT chest
- bone scan if symptomatic
Two features of Kidney cancer staging and grading with their breakdown
Fuhrman grade - differentiation ( 1 well - 3/4 poor)
TNM staging of RCC - Tumour size greater or less than 7, outside kidney a bit, outside kidney a lot
N1 – Met in single regional LN
N2 – met in ≥2 regional LN
M1- distant met
Kidney Cancer management
Gold standard:
Partial nephrectomy (single kidney, bilateral tumour, multifocal RCC in patients with VHL, T1 tumours (up to 7cm)
Radical Nephrectomy
In patents with small tumours unfit for surgery – Cryosurgery
Metastatic disease
- Receptor Tyrosine Kinase inhibitors, Immunotherapy
Types of bladder cancer
transitional cell carcinoma
squamous cell carcinoma - schistosomiasis is endemic
Adenocarcinoma
Aetiology of bladder cancer
Smoking, Occupational exposure, Chronic inflammation of bladder (including long term catheter use), Drugs, Radiotherapy
Clincial features of bladder cancer
Painless haematuria/persistent microscopic haematuria
Suprapubic pain
Lower urinary tract symptoms and UTI
Metastatic disease symptoms –bone pain, lower limb swelling
Investigation for bladder cancer following Painless visible Haematuria
Flexible cystoscopy
CT urogram
Renal function
Investigation for bladder cancer following Persistent microscopic haematuria
Flexible cystoscopy
US KUB
Two features of bladder cancer staging and grading with their breakdown
TNM
Ta – non invasive papillary carcinoma
Tis – carcinoma in situ
T1 – invades subepithelial connective tissue
T2 – invades muscularis propria
T3 – invades perivesical fat
T4 – prostate, uterus, vagina, bowel, pelvic or abdominal wall
N1 – 1 LN below common iliac birufication
N2 - >1 LN below common iliac birufication
N3 – Mets in a common iliac LN
M1- distant mets
Who classification ( G1 well - G3 poorly differentiated)
Management of bladder cancer
Non Muscle Invasive
- If low grade and no CIS then consideration of cystoscopic surveillance +/- intravesicular chemotherapy/BCG
Muscle Invasive
Cystectomy
Radiotherapy
+/- chemotherapy
Palliative treatment
Type of prostate cancer
adenocarcinoma