Renal Diagnostics Flashcards
What lab measurement is released into the circulation at a relatively constant rate, has a stable plasma concentration, and is freely filtered across the glomerulus and excreted by the kidney?
Serum creatinine
What lab measurement is a product of protein catabolism, is excreted by the kidneys, and can be elevated with dehydration, GI bleed, or meds such as steroids and tetracyclines?
BUN
What lab measurement is commonly used as a marker for volume status?
BUN/ creatinine ratio
What measurement is used to measure the # of functioning nephrons and is used to track progression/ regression of disease and dose medications?
GFR
Can GFR be measured directly?
No, must be calculated
Creatinine clearance is helpful to know when what?
Choosing or dosing meds
CKD is defined as the presence of kidney damage or decreased kidney function for how long?
≥ 3 months
If a pt presents w hx of no urine output, what should you be concerned about? (generally)
Very concerning- renal failure
What stage of kidney disease is a pt considered if they are on dialysis?
End stage renal disease/ kidney failure
Pt with the following is in what stage of CKD? Kidney damage with N or ↑ GFR GFR ≥ 90
Stage 1
Pt with the following is in what stage of CKD? Kidney damage with N or ↓ GFR GFR 60-89
Stage 2
Pt with the following is in what stage of CKD? Moderately ↓ GFR (30-59)
Stage 3
Pt with the following is in what stage of CKD? Severe ↓ GFR (15-29)
Stage 4
Pt with the following is in what stage of CKD? Kidney failure GFR < 15 or on dialysis
Stage 5
You might order ANA levels if you suspect what?
SLE
You might order C-ANCA and P-ANCA levels if you suspect what?
Granulomatosis w polyangitis
You might order anti-GBM levels if you suspect what?
Goodpasture syndrome
You might order antistreptolysin O levels if you suspect what?
Post-strep glomerulonephritis
You might order SPEP and UPEP levels if you suspect what?
Multiple myeloma
What lab value has the potential to improve estimates of GFR?
Cystatin C
Prostate-specific antigen (PSA) can be used for what?
Screening for early detection of prostate cancer and to monitor disease after treatment
When should you consider testing PSA levels in men?
Consider ~50 yo (but shared decision making)
Men with an abn PSA should be what?
Referred to urology
What 2 values on a urinalysis can indicate possible kidney issues?
Protein and blood (always further investigate)
What test is used in the work-up to find the cause of kidney disease?
Microscopic urinalysis
On microscopic urinalysis, a pt with glomerulonephritis or vasculitis might show what?
RBC casts
On microscopic urinalysis, a pt with acute pyelonephritis might show what?
WBC casts
On microscopic urinalysis, a pt with acute tubular necrosis might show what?
Epithelial cell casts
On microscopic urinalysis, a pt with dehydration might show what?
Hyaline casts
On microscopic urinalysis, a pt with abn levels of uric acid, calcium phosphate or calcium oxalate, cystine, or magnesium ammonium phosphate (struvite) might show what?
Crystals
What urine study id’s the causative organism of a urinary infection and shows sensitive and resistance abx?
Urine C+S
What urine finding serves as the earliest clinically detectable stage of diabetic nephropathy?
Microalbumin
What urine study is most commonly seen in acute interstitial nephritis?
Urine eosinophils
What urine study provides a better quantitative measurement for proteinuria or GFR determination?
24-hour urine collection
Bence Jones are a positive for what test, leading to suspicion for MM?
Urine protein immunoelectrophoresis (UPEP)
What may be a helpful initial diagnostic tool but is not typically used clinically?
Abd x-ray (KUB or abd)
While a KUB study can identify calcium-containing, struvite, and cysteine stones, what will it likely miss (making it NOT 1st line imaging)?
Smaller stones, radiolucent stones (uric acid) or stones overlying bony structures
What are stones involving the renal pelvis and extending into ≥ 2 calyces?
Staghorn
What is the appropriate initial test in patients with renal failure of unknown etiology?
Renal US
What is the test of choice to exclude urinary tract obstruction?
Renal US
What is the test of choice for evaluating renal vascular flow?
Renal doppler US (can also use CT angiography)
What imaging provides more detailed info than US, helps distinguish between types of cysts and masses, and is used to eval and stage renal cell carcinoma?
CT scan
What is the diagnostic test of choice for nephrolithiasis?
Non-contrast CT
What cautions should you be aware of when using a contrast CT?
Contrast potentially nephrotoxic Hold metformin for 48 hrs post
What is the gold standard for diagnosis of renal vein thrombosis?
MRI
What c/i should you be aware of with Gadolinium in MRI testing?
May increase risk of nephrogenic systemic fibrosis in pts with chronic or acute renal failure
What diagnostic test is used to eval size/ shape of kidneys/ ureters/ bladder, kidney stones, and obstruction (although NOT used frequently)?
Intravenous pyelogram (IVP)
How is excretory fxn of the kidneys measured with IVP?
Length of time for passage of contrast through kidneys
What test is used for preoperative mapping of renal vasculature (if needed)?
Renal angiography
What might you be concerned for if you see bilateral radiopaque branched, staghorn calculi filling on collecting systems on KUB?
Nephrolithiasis
What might you be concerned for if you see triangular hypodense streaks spreading from the pelvis to the renal cortex on CT scan?
Bilateral pyelonephritis
What might you be concerned for if you see a “string of pearls” appearance on angiography?
Fibromuscular dysplasia
What test is used to obtain a renal sample to assist with dx?
Renal bx
What test involves the bladder being filled with contrast and x-rays being taken to visualize contrast?
Cystourethrogram
Primary bladder conditions such as vesicoureteral reflux, distortion of the bladder, fistula, and perforation are better seen with what study (compared to IVP)?
Cystourethrogram
What test is a scope of the bladder involving a thin fiberoptic tube passed through a hollow sheath?
Cystoscopy
What should be expected post cystoscopy, and how soon after should this clear?
Post-procedure hematuria, should clear w/i 3 voids
What test is used to assess bladder and ureteral involvement due to malignancies, to eval urogynecologic conditions, and to dx intrinsic bladder disease?
Cystoscopy
What should be ordered in all male pts complaining of testicular pain?
Testicular US
What test is used to eval of testicular/ scrotal masses or pain, testicular size, location of undescended testes and what else should you get with this test?
Testicular US, should also get a doppler to look at BF
How is a prostate US and biopsy performed and what does it help detect?
Transrectally Helpful in detection of prostate cancer in pts with increased PSA
