Renal disorders: Flashcards
Renal diseases:
Obstructive Uropathy:
• Any condition, structural or functional, causing a
change in the normal urine flow anywhere within the the urinary tract.
• Causes vary with age and gender
• Congenital disorders (e.g.uretopelvic junction obstruction) in young children
• Nephrolithiasis (kidney stone formation) in young men
• Pregnancy in young women
• Benign or malignant tumours in
Consequences of Obstruction:
- Pain
Pain
- The distention caused by the blockage causes
pain. The intensity usually reflects the rapidity
rather than degree of blockage.
• Acute blockage of the ureter may be
associated with excruciating pain, whereas slowly developing obstruction may be completely painless
Outcome: Obstructive uropathy:
Important to clear obstruction as soon as possible -‐ Why?
– Fibrosis, tissue damage/apoptosis, nephron and renal function affected within
7 days
– By 14 days damage to distal and proximal tubules of the nephron
– 3-‐4 weeks damage is irreversible depending on severity of obstruction
• Does GFR improve after obstruction removal?
– Depends on how quickly it is treated
• What electrolyte abnormalities are associated with obstructive uropathy?
– Hyperkalaemia and metabolic acidosis
– Due to defects in the excretion of potassium or hydrogen.
Outcome - Obstructive uropathy:
Hypertension in obstructive uropathy -‐ why?
– Increase in blood volume
– Hypertension may be a secondary to renal failure in bilateral obstruction due to extracellular fluid volume expansion
– In acute unilateral obstruction increased renin secretion is usually
responsible.
• Complications
– Renal dysfunction/failure, cardiovascular (increase in blood volume
and electrolyte disturbances)
• Urinary tract infection
Renal Calculi
- If flow blocked, urine backs up in pelvis
- Pressure forces filtrate back into interstitum
- Pressure causes atrophy of renal tissue and compression of vessels in m
Renal Calculi:
• Masses of crystals, proteins, other substances • Common cause of urinary tract obstruction • Usually unilateral
Consequences of Obstruction:
- Complete obstruction:
Decreased glomerular filtration and resulting renal failure.
Consequences of Obstruction:
- Hydroureter:
Obstruction of the ureter with accumulation of urine
Consequences of Obstruction:
- Hydronephrosis:
retrograde increases in hydrostatic pressure in the renal pelvis and calyces can increase accumulation of urine in the renal collecting system.
Consequences of Obstruction:
- Partial obstruction:
Chronically can cause compression, accumulation of urine, ischemic damage and atrophy with decreased concentrating ability of the
kidney.
Hydroureter and hydronephrosis:
• Obstructive uropathy 5 : pathogenesis
• Renal tubules affected first
• Impaired concentration, then reduced GFR
• Kidney enlarged, pelvis and calyces are
dilated, calyces blunted
• Cortical tubules lost, with interstitial fibrosis.
Clinical signs and symptoms
Hydroureter and hydronephosis:
• Pain - Colicky with stones
• Bladder symptoms (eg, prostatic enlargement): urgency, hesitancy, frequency
• Unilateral obstruction, complete or partial is often asymptomatic
• Bilateral partial obstruction – can’t
concentrate urine: polyuria, nocturia, possibly acidosis and hypertension
• Bilateral complete obstruction: oliguria/anuria
• If malignant – may see haematuria
• Detect via intravenous pyelogram or
ultrasound
Nephrolithiasis - Kidney Stones
types of stones?
- Calcium (75-‐80%)
- Struvite (15%) (Magnesium ammonium phosphate)
- Uric acid (7%)
- Cysteine (1%)
Nephrolithiasis - Kidney Stones
Pathophysiology
Pathophysiology • High urinary concentration of stone forming substances • Changes in pH and temperature • Drugs and diet • Decreased urinary flow • Grow in the renal papilla
Nephrolithiasis - Kidney Stones:
Risk factors:
CALCIUM STONES (phosphates, oxalates)
- Smallest
- Middle-‐aged men with family history
- Hypercalciuria – Elevated calcium in urine
- Hyperuricosuria – Excess uric acid in urine
- Bone demineralisation, following prolonged immobility, hyper- parathyroidism
- Diet high in vegetables –high oxalates
Nephrolithiasis - Kidney Stones:
Risk factors:
STRUVITE STONES
•
Mg(NH
4
)PO
4
-‐magnesium ammonium
phosphate
•
Women infected by microbes eg proteus and
pseudomonas
•
These split urea to ammonia, producing
alkaline urineNephrolithiasis - Kidney Stones:
Risk factors:
URIC ACID STONES
- Conditions → concentrated acidic urine:
- Ulcerative colitis or regional enteritis with fluid and bicarbonate loss,
- Sufferers with gout, high meat and fish diet, (purines broken down to uric acid)
- Leukaemia - cell breakdown
Nephropathy
CYSTEINURIA
- Rare hereditary disorder
- Disorder of amino acid metabolism
- Decreased tubular reabsorption of cysteine
Pathophysiology
• Stone formation not well understood
• High levels of stone-‐forming substances in plasma &
urine, some medications
• Loss of inhibitors of precipitation
• High pH favours struvite stones & deposition of Ca2+
• with oxalate, phosphates & carbonates
• Low pH (acid) favours uric acid stones, as calcium urate
• Low urine output & high concentration
•Found in papillae, renal tubules, calyces or pelvis, most < 5mm, passed in urine
Nephropathy - CYSTEINURIA
Clinical Manifestations
- Colicky pain ‐ muscle spasm of ureter
- Flank pain, at costovertebral angle, may radiate into groin
- Nausea & vomiting with severe pain
- Haematuria
Bladder - prostate enlargement,
hypertrophy & calculus:
Stone blocks exit from
bladder when muscles contract
Bladder - prostate enlargement,
hypertrophy & calculus
- diagnosis?
- Blood & urine tests for stone forming substances
- Urine pH
- Red and white blood cells in urine
- Stones in urine (microscopy)
- Intravenous pyelogram
- GFR
- Computed Tomography, Ultrasound
Bladder - prostate enlargement,
hypertrophy & calculus
- treatment and management:
• Adequate analgesia and high fluid intake
• Treat infections
• Dissolve stones and prevent reformation by:
- Increasing fluid intake and increasing urine output
- Decrease dietary intake of stone-‐forming substances –Alter urine pH(Diet)
• Surgical removal of stones greater
than 0.5cm in width percutaneous puncture of kidney with forceps removal
• Shock wave lithotripsy for large calcium stones
Bladder - prostate enlargement,
hypertrophy & calculus
- predisposing factors?
Family history and childhood infection relevant • Diabetes • Chronic disease • Renal calculi • Urinary tract obstruction • Immunosuppression • Pregnancy • Prostate disease in older
