Genitourinary COPY Flashcards
What are the major functions of the Kidney?
- Filter or secrete waste/excess substances
- Retain albumin and circulating cells
- Reabsorb glucose, amino acids and bicarbonates (Acid-base regulation)
- Control BP, fluid status and electrolytes
- Activates 25-hydroxy vitamin D (by hydroxylating it to form 1,25 dihydroxy
vitamin D) - Synthesis erythropoietin
Explain the Renal Blood Flow
Renal artery 🡪 interlobar artery 🡪 arcuate artery 🡪 interlobular artery 🡪 afferent arteriole 🡪 glomerular capillary 🡪 efferent arteriole 🡪 peritubular capillary around tubules
The peritubular artery is important in that secretion and reabsorption to/from filtrate is often active and requires energy and oxygen. Therefore, blood supply is crucial.
What is the Glomerular Filtrate rate?
The volume of fluid filtered from the glomeruli into Bowman’s space per unit
time (minutes)
Why is Creatinine a good marker for GFR?
Creatinine used as a marker of GFR because:
Freely filtered
Not metabolised
Not secreted
Not reabsorbed
What factors favour and oppose filtration in the glomerulus?
Favouring filtration = hydrostatic pressure from glomerular capillary
Opposing filtration = hydrostatic pressure from Bowman’s capsule and oncotic pressure from glomerular capillaries
Forward action favoured – so hydrostatic pressure from the glomerular capillary is the biggest
What is the normal GFR?
120ml/min
What mechanisms control renal perfusion and function?
Autoregulation:
Increase blood flow in afferent arteriole 🡪 stretch of wall 🡪 smooth muscle contract 🡪 arteriolar constriction
Systemic circulation BP doesn’t affect renal circulation
Tubuloglomerular feedback:
Macula densa (in DCT) detect levels of NaCl
Low levels of NaCl🡪 release prostaglandins 🡪 granular cells release renin which activates RAAS system
High levels of NaCl 🡪 sends signal to afferent arteriole causing vasoconstriction which will decrease GFR and lower BP
Give an example of a Loop Diuretic, its MOA and Side effects?
Furosemide:
Moa - Ascending limb, inhibits NKCl2 transporter
SE - Dehydration, hypotension, hypokalaemia, metabolic alkalosis (can cause ototoxicity)
Give an example of a K+ sparring Diuretic, its MOA and SE?
Amiloride/Spironolactone:
MOA - Act on DCT, inhibit ENaC channels to reduce sodium reuptake and therefore water
SE - GI upset, HYPERkalaemia, metabolic acidosis, gynaecomastia
Give an Example of a Thiazide Diuretic, its MOA and SE?
Bendroflumethiazide
MOA - Act on Na/Cl transporter in DCT
SE - HYPOkalaemia, Metabolic alkalosis, Hypovolaemia, Hyponatraemia, Hyperglycaemia in DM
What is Nephrolithiasis?
Renal Stones (calculi) commonly made from Calcium Oxalate (90%) which form in the CD and can be deposited anywhere from the renal pelvis to the urethra.
What are some other types of renal stone compared to calcium oxalate?
Calcium phosphate/oxalate (80%)
Uric Acid (10%)
Cysteine Stones
Struvite (infection often from proteus)
What are the 3 main narrowing’s where renal stones may be found?
- Pelviureteric junction (PUJ)
- Pelvic brim
- Vesicoureteric junction (VUJ)
What is the epidemiology of Renal Stones?
10-15% lifetime risk
More common in males
Peak age 20-40 yrs
Increasing Incidence
What are the risk factors for renal stones?
Anatomical abnormalities
Hypercalciuria
Hypercalcaemia
Hyperparathyroidism
Family history / PMHx of Renal Stones
Hypertension
Gout
Immobilisation
Dehydration
Low urine output
Primary kidney disease
What are the main causes for renal stones?
Anatomical:
Congenital - horseshoe kidney
Acquired - Obstruction, trauma, reflux
Urinary Factors:
Metastable urine
Increased Calcium oxalate, urate, cystine
Infection induced - Proteus leads to Struvite stones
Dehydration
What is the pathophysiology of renal stones?
Excess solute in the collecting duct
Supersaturated urine - favours crystallisation
Stones cause regular outflow obstruction - lead to hydronephrosis
Subsequent dilation of the renal pelvis will lead to lasting kidney damage
What are the 2 key complications of renal stones?
Obstruction - leading to AKI
Infection - causing obstructive pyelonephritis
What is the presentation of Renal Stones?
Maybe ASx and never cause issue
Renal colic is presenting complaint in Symptomatic kidney stones:
Loin to groin pain that is colicky (peristaltic waves leading to fluctuations in severity)
LUTS symptoms (dysuria, strangury Urgency, Frequency)
Px cant lie still
What are the signs of renal stones?
Features of acute pyelonephritis or gram-negative septicaemia if there is infection associated in an obstructed urinary system
Bladder stones – urinary frequency and haematuria
Urethral stones – cause bladder outflow obstruction, resulting in anuria and painful bladder distension
What is Colicky Pain?
Pain that fluctuates in severity often due to peristalsis causing contaction of gallstones/renal stones which then settles when the contraction stops
What are the symptoms of Renal Colic?
Loin to groin pain
Px cannot lie still
Haematuria/dysuria
Nausea or vomiting
Reduced urine output (LUTS)
Symptoms of sepsis, if infection is present
What are the primary investigations for Renal stones?
1st Line - KUB (kidney, Ureter, Bladder) XR - 80% specific
Gold Standard - NCCT (non-contrast CT) KUB - 99% specific (diagnostic)
Bloods:
FBC
U&Es - raised creatinine in AKI
Urinalysis -Microscopic haematouria
Pregnancy test
Urine dipstick - UTI
What investigation would be used for hydronephrosis from a suspected renal stone for a Px who is pregnant?
Ultrasound as they cannot have CT