Urinary Flashcards
Which diuretic might cause someone to present with a decrease in glucose tolerance, uricemia (uric acid in the blood) and hypokalaemia?
Thiazides
- effect the Na+/Cl- pump, sodium and glucose are absorbed together
Which diuretic can cause hypokalaemia , metabolic alkalosis and reversible ototoxicity?
Loop diuretics- potent naturiesis
- can also affect hair cells in the inner ear
What are loop diuretics used to treat?
Severe oedema, hyperkalaemia, hypercalcemia and acute renal failure (to increase urine flow)
Which drug reduces mortality by 30% in HF and LV dysfunction patients?
Spironolactone
Most common chief complaint associated with UTI in males?
Dysuria
Most likely UTI pathogen in a catheterised patient?
Staph. epidermidis
Describe the journey of a ureter
Arises from renal pelvis, descends on top of psoas major to reach the brim of the pelvis, crosses in front of the common iliac arteries, runs along the lateral walls of the pelvis, then curves antero-medially to enter the bladder
List the retroperitoneal viscera
SAD PUCKER
Suprarenal glans
Aorta/IVC
Duodenum (2nd and 3rd segments)
Pancreas Ureters Colon (ascending and descending) Kidneys oEsophagus Rectum
If you can see the hila of both kidneys and lumbar verterbrae, what level is the CT at?
L1-L2
How would a blockage of the Bowman’s capsule which causes an increase in pressure affect the net filtration pressure GFR?
It would decrease - there should be a movement from capillary - Bowman’s but it is harder to filter the blood out because the hydrostatic pressure in the Bowman’s is against the hydrostatic pressure in the capillary.
Describe normal oncotic pressure in Bowman’s capsule
Negligible- no proteins are filtered here
What would happen to GFR if glomerular oncotic pressure decreased?
It would increase
More oncotic pressure = more proteins = harder to filter
Less oncotic pressure = less proteins = easier to filter
Where has fluid leaked from if it has a very similar composition to plasma?
Bowman’s capsule
What constituent of the filtrate has a rate of urinary excretion > glomerular filtration in a healthy adult?
Glucose
Give the clearance equation
(Urine conc of substance x urine flow rate) / plasma conc
- units L/hr
What compensatory mechanism will occur in the nephron of a patient with orthostatic hypotension?
An increase in glomerular filtration rate of the same nephron.
- Immediately on standing BP falls
- Decrease in NaCl to macula densa
- Macula densa triggers 2 things - vasodilation of afferent arteriole to increase perfusion of kidney, and increased paracrine stimulation of JGA cells so more renin is released
Features of the ascending loop of Henle?
permeable to ions but impermeable to water
(thin ascending limb does minimal Na and Cl transport, thick ascending limb does more as it has NKCC and Na+K+ATPase)
ABSORB SOLUTE, WATER LOST
Features of the descending loop of Henle?
permeable to water and ions
H2O moves out and Na+ and Cl- move in so its more concentrated as you go down
What stimulates the granular cells of the JGA to release renin?
Drop in BP, decreased NaCl to macula densa, sympathetic stimulation
What does ADH do other than upregulate aquaporins?
Vasoconstriction - activates V1 receptor on VSM (vascular smooth muscle) - triggers thirst response from hypothalamus
What is diabetes insipidus?
Inability to reabsorb water from distal nephron due to failure of excretion or action of ADH
Central - damage to hypothalamus or pituitary , tx with nasal spray/ADH injections
Nephrogenic- insensitivity to ADH, tx with low salt low protein diet
What is dipsogenic diabetes insipidus (or primary polydipsia) ?
Damage to hypothalamus causing malfunction of the thirst mechanism
What is measured by urine specific gravity following water deprivation?
Renal concentrating ability
Which blood vessel relates to CCM?
vasa recta
What removes K+ from the body?
Calcium resonium (calcium gluconate stabilises myocardium and insulin redistributes)
What might cause hypokalaemia in a bulimic patient?
Give another cause of loss of serum potassium
Losing potassium from kidneys to correct acid balance
- she has a metabolic alkalosis from vomiting so not enough H+ in cells, so K+ leaves the blood to enter cells to try and compensate
Other cause is a thiazide diuretic
How can trimethoprim affect potassium levels?
Competitive inhibitor for ENaC (similarly to amiloride) so causes hyperkalaemia
What fluid replacement could you use for a surgical patient who is tachycardic with low bp?
Hartmann’s over 15 mins
What fluid replacement could you give someone with severe diarrhoea?
Potassium cannot be given quickly
1L 0.9% sodium chloride with 40mM potassium over 8 hours
What fluid replacement would you consider for an elderly patient who is NBM?
NBM- must replace glucose
Elderly- dont fluid overload too quickly
1L 0.18% sodium chloride and 4% dextrose over 12hours
Treatment for AKI and electrolyte imbalance that cannot be corrected by medication?
Haemofiltration - better then dialysis in acutely unwell haemodynamically unstable patients
Urinary symptoms/AKI associated with hypotension and/or trauma are usually due to…
ACUTE TUBULAR INJURY
- if you dont know just say this
How do the convoluted tubules regulate body pH?
Reabsorption of HCO3- (90% in PT)
Screening for early kidney disease is important in…
Diabetics
How does PTH affect the kidneys handling of phosphate?
Decreases reabsorption in PCT
Short term and long term calcium regulation?
Short term- PTH
Long term- calcitriol
Early sign of glomerulosclerosis in diabetic?
Microalbuminuria
Pathological finding on biopsy for patient with rapidly progressive GN?
Glomerular crescents- leakage of fibrinogen into bowman’s space
Action of which nerves cause detrusor contraction?
Parasympathetics from spinal cord to urinary bladder
Stimulation of which receptor would reduce incontinence in a patient with OAB?
B3 receptors- would relax the detrusor muscle
What innervates the EUS?
Somatic motor neurones- conscious control
What is normal bladder capacity?
400-500ml
Where is the detrusor muscle derived from embryologically?
Hind gut
Radiopaque lesion present in bladder area, which other lab finding will be likely?
Hypercalciuria- secondary to bladder calculi
Renal impact of AAA at L2-3?
Ureter trapping- unilateral hydronephrosis
Describe urea concentration throughout the nephron. How does ADH play a role?
- Normal level until reaches the loop of Henle where urea concentrations are very high - most urea enters the nephron here from the medulla.
- Some more reabsorption happens in the PCT.
- Urea stays high in the DT because it is impermeable to it.
- In the collecting duct loads of urea gets pumped back into the medulla (recycling).
ADH stimulates even more urea uptake by activating urea transporters and urea is an osmole so water follows.
Why does the IUS need to be stronger in men?
Prevent retrograde ejaculation
What receptor is found on the IUS?
alpha 1
Where in the nephron do amino acids and glucose get reabsorbed ? (bulk of reabsorption happens here)
PCT
Describe reabsorption at the PCT
Reabsorption is isosmotic
• PCT responsible for ‘bulk’ reabsorption of
many solutes
• Very metabolically active, high concentration
of mitochondria
• Provide energy for Na/K ATPase
What is sodium reabsorbed with and why?
Takes place in association with Cl- and HCO3-
Needed to maintain neutrality of cells
Which substance is more concentrated at the end of the PCT than the beginning?
Creatinine
Is urea actively secreted from renal tubular cells?
No it moves passively
How does ADH cause water movement via urea recycling?
ADH increases number of urea transporters, more urea moves into medulla, water follows as urea is an osmole
An increase in the conc of plasma potassium causes an increase in….
aldosterone release - aldosterone upregulates ROMK channels to increase K+ excretion
In the presence of ADH the Distal nephron is permeable to …
water and urea
What makes ammonia an effective urinary buffer?
The walls of the renal tubules are impermeable to NH4
+ - it becomes “locked” in the tubule
Renal correction of acute hyperkalaemia will result in…
Acidosis
What 3 components make up the filtration barrier?
Endothelial cells, BM, podocytes
Where do you find the glomerulI?
In the renal CORTEX
What is the tubuloglomerular feedback mechanism in high tubular flow?
Macula densa cells of the DCT epithelium detect osmolality or the rate of movement of Na+ or Cl- movement into the cells. The higher the flow of filtrate the higher the Na+ concentration in cells.
A signal is sent via the juxtaglomerular cells, triggered by
an increase in NaCl concentration of distal tubular fluid.
ATP released, converted to adenosine, binds with A1
receptor on afferent arteriole.
Further vasoconstriction of the smooth muscle of the
adjacent afferent arterioles and therefore ↓ RPF which in
turn ↓GFR. Renin synthesis inhibited.
What is the tubuloglomerular feedback mechanism in low bp?
Release of prostaglandins – attenuate constriction of afferent arteriole
Renin released by juxtaglomerular cells. 3 stimuli responsible for release:
• Sympathetic nerve stimulation
• ↓ stretch of afferent arteriole
• Signals generated by macula densa cells in response to ↓NaCl delivery
RAAS system
Fluid leaving the is….
hypotonic
