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13 Cards in this Set
- Front
- Back
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How much blood flow does the kidney get?
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20%
90% to cortex, 10% to medulla |
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How is serum creatinine used?
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Creatinine is made in muscle cells proportionally to muscle mass
85% filtrated, 15% secreted (low enough) in the PCT Estimates GFR by the Cockcroft-Gault formula (age, sex, weight, SCr) or MDRD (age, sex, race, SCr, Serum BUN, Serum albumin), or a 24-hr urine collection Hyperbolic relationship with GFR: at normal levels, a small change in SCr reflects a large change in GFR Caveats: patient must be in steady state, SCr can be artificially changed, and this can't be used with patients with hepatic cirrhosis, amputations, morbid obesity or spinal cord injuries |
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How is the GFR estimated?
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creatinine clearance
inulin (gold standard, rarely actually done) serum cystatin C (surrogate marker, research only) |
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What does a dipstik measure?
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blood (detects peroxidase in blood, myogobin, free hemoglobin)
PMN (detects leukocyte alkaline esterase) bacteria (nitrate reaction with an azo dye) protein (depends on urine concentration, so any positive value is significant) specific gravity (estimates osmolality) |
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He mentioned in the lecture (not in syllabus): what are sediments found in urine?
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casts: granular suggests tubular injury (RBC: glumerulonephritis, WBC: acute interstitial nephritis, hyaline membranes: volume depletion)
hematuria: see at least 3 RBC in the microscope view, can be dismorphic (glomerular problem) or normal can determine the kind of kidney stone present: oxalate (pyramidal), cystine (hexagonal), triple phosphate, uric acid |
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What are some indications for ultrasound?
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kidney size
hydronephrosis kidney mass abscess hematoma ADPKD localize kidney for procedure doppler for kidney vein thrombosis, kidney blood flow |
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What are some indications for IVP?
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renal size and contour
recurrent UTI *calculi urinary tract obstruction find cause of hematuria |
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What are some indications for a radionucleotide scan?
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total kidney function and individual kidney contributions
obstruction look at parenchymal integrity infection scar renovascular HTN Little benefit if single kidney has GFR < 15 mL/min |
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What are some indications for a renal scan?
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GFR agents: measure GFR
technetium: tubular secretion agent: shows renal blood flow and function (plasma clearance) tubular fixation agents: binds tubules and delineates contours of functional tissue to assess cortical scarring from pyelonephritis/vesicoureteral reflux |
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What are some indications for a CT?
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for a renal mass
calcification pattern nonfunctional kidney extent of renal trauma guide for needle aspiration or biopsy investigate an adrenal cause for HTN |
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What are some indications for an MRI?
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complex masses
renovascular lesions to stage neoplasms pheochromocytoma renal vein thrombosis alternative for CT for a contrast medium allergy |
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What are some indications for an angiography?
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artery lesions
large vessel vasculitis unexplained hematuria kidney transplatnation renal vein thrombosis dx for complex/unusual masses *can be used therpeutically (eg for an obstruction) uses iodine contrast--> can be dangerous to the kidney. AE: embolization, vessel damage |
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When would you do a renal biopsy?
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if signs and sxs suggest parenchymal diseases
if ddx has many diseases with different tx or prognosis for acute kidney disease, nephrotic or nephritic syndrome, hematuria, systemic disease, transplant allograft |
