intro to nephro Flashcards
Glomerulus
tuft of capillaries interposed between the afferent and efferent arterioles-housed in an epithelial cell capsule: bowmans capsule.
filtrate must pass through 3 layers
fenestrated endothelial cell, glomerular basement membrane, epithelial cell
JGA
contains macula densa and JG cells located in the afferent arteriole. JGA cells also synthesize and store prorenin which is cleaved into active renin and secreted into the afferent arteriole in response to renal hypoperfusion
tubuloglomerular feedback
mechanism of autoregulation. mediated by cells in the macula densa which sense the change in NaCl delivery. this helps to regulate GFR.
functions of the kidney
regulate volume and composition adjusting excretion of water and electrolytes excretion of waste and metabolic breakdown products hormonal regulation EPO production Vitamin D metabolism renin angiotensin aldosterone axis regulation of low BP or blood volume
hormonal regulation-kidney function
metabolic degradation of peptide hormones such as pituitary hormones, glucagon, insulin
renin-angiotensin-aldosterone axis
renin is produced in JGA cells from prorenin. It is secreted into the afferent arteriole in response to various stimuli which cause renal hypoperfusion such as low BP, and decreased effective circulating volume.
Renin converts angiotensin 1->2 which causes:
systemic vasoconstriction (raising systemic BP) Na and water re absorption in PT which helps to restore volume Secretion of aldosterone
upper urinary tract symptoms of renal disease
flank pain or tenderness: renal infection, infarction, GN, rarely obstruction
Lower urinary tract infection symptoms
dysuria, frequency, urgency
bladder outflow obstruction symptoms
impaired urinary flow, hesitancy, dribbling, incomplete emptying of bladder
sphincter or bladder wall dysfunction symptoms
urinary retention, incontinence, enuresis
increased urine pH think:
infection with urea splitting organism
systemic alkalosis, renal tubular acidosis, carbonic anhydrase inhibitors
urinalysis finding of protein in urine
persistent indicates renal disease.
BUN
increases seen with *dietary intake (high protein) *high catabolic rate and tissue breakdown (hemorrhage, trauma, glucocorticoid therapy) *dehydration normal to low *muscle wasting and liver disease
GFR estimation
24 hour creatinine clearance most common
also can use cockcroft-gault or MDRD formula
cockcroft-gault equation
(140-age) X (body weight in kg)/72 X SCr (women multiply result of .85
renal ultrasound is used for:
assess size, shape, and location of kidneys.
- masses
- obstruction/hydronephrosis
- fluid collections or other signs of inflammation/infection
- MAY detect nephrolithiasis
indications for renal ultrasound
hematuria, acute kidney injury, flank pain, safe during pregnancy
intravenous pyelogram
- contrast is administered via IV
- helpful in identifying obstruction and stones
- contrast CT has taken its place in most institutions
- risk of contrast induced nephropathy
CT scan
- helpful in evaluation of stones, renal masses, complex cysts, perinephric and vascular pathology
- CI is pregnancy and no contrast with renal disease
- gold standard for nephrolithiasis and doesn’t require contrast
renal MRI indications
hematuria, renal mass, suspected renal vascular issue
MRI is better than CT for:
characterizing abnormal tissues/masses especially when there is concern for malignancy.
cystoscopy indications
- frequent UTIs
- hematuria
- incontinence or overactive bladder
- painful urination, chronic pelvic pain, or interstitial cystitis
- nephrolithiasis that is obstructing and unlikely to pass
- mass, polyp, suspected malignancy
voiding cystourethrogram (VCUG)
a radiologic study during which a radiologist observes contrast movement from the bladder and urethra.
-looking for signs of vesicoureteral reflux, extravasation of contrast or obstacle to bladder emptying.
indications for VCUG
recurrent UTI, bladder trauma or rupture, suspected obstruction
