ABIM 2015 - Nephro Flashcards
(585 cards)
GFR is used to assess KIDNEY FUNCTION and SERUM Cr, to ESTIMATE the GFR. What happens to the Cr when the GFR is REDUCED by 50%?
It DOUBLES (so a GFR of 60 that drops to 30 will make a Cr that is 1.0 increase to 2.0)
What is the SERUM Cr expected to do in the setting of NEPHROTIC syndrome?
DECREASE ( due to tubular over secretion) and thus not well correlated with kidney function or GFR estimation
What effect do CIMETIDINE and TMP (TMP-SMX) have on SERUM Cr?
INCREASE it without any change in the GFR
Muscle wasting, Protein malnutrition, Cirrhosis, Poor kidney perfusion, GI BLEED, meds all AFFECT these COMMONLY-used renal laboratory markers WITHOUT any actual changes in KIDNEY FUNCTION?
BUN and Cr
In extremes of HEIGHT and WEIGHT, PREGNANCY, patients who have had AMPUTATIONS, or CIRRHOSIS should have their GFR measured how?
Based of 24 HOUR URINE collection
What test measures the GFR very precisely?
Radionuclide Kidney Clearance Scanning
What GFR estimation do MOST labs use and is the BEST estimation of GFR in CHRONIC KIDNEY DISEASE (CKD)?
MDRD equation and they report HIGH GFR levels as >60 mL/min
How is a PROPER urine sample obtained?
Clean Catch, Mid-stream or via Bladder Catheterization and EXAMINED within 1 HOUR of collection
This measurement of urine is a ratio of the weight of urine to an equal quantity of water and an indication of the kidney’s ability to maximally dilute or concentrate the urine?
SPECIFIC GRAVITY
A specific gravity of urine of 1.005 is? If 1.030?
SG - 1.005 is DILUTE (close to water)
SG - 1.030 is CONCENTRATED “dehydrated’
High protein diets result in consumption of a high “ACID-ash” content and the need for the kidneys to excrete the acid load making the urine more ACIDIC (pH 5.0 - 6.0), conversely, a STRICT VEGETARIAN diet results in a more alkaline urine with a pH of ≥7.0. What infections and condition causes an ALKALINE urine?
Distal RTA, PROTEUS and PSEUDOMONAS
High-alkaline urine (as in vegetarian diets) result in what false-positive component result on a urine DIP STICK?
False HIGH-PROTEIN (albumin) level
When the urine DIP STICK test is NEGATIVE for protein (albumin) but there is suspicion for MULTIPLE MYELOMA, what test can be done on the urine to evaluate for the presence of LIGHT-CHAINS?
SULFOSALICYLIC ACID (SSA)
What is the BEST estimate of GFR in PREGNANT WOMEN, EXTREMES of AGE/WEIGHT, AMPUTEES and CIRRHOSIS?
Cr Clearance
When does glucose spill into the urine and is therefore detected on urine DIP STICK?
When serum glucose >180 mg/dL OR in PROXIMAL RTA
ONE of these THREE (3) substances is detected on the urine DIP STICK when there is DKA, SALICYLATE TOXICITY, ISOPROPYL ALCOHOL POISONING, STARVATION, however, the OTHER TWO (2) are NOT detected (such as in ALCOHOLICS), why?
KETONES (acetoacetate)
Because alcoholics with ketoacidosis make β-hydroxybutyrate which is NOT detectable on urine DIP STICK, neither is acetone (the three ketoacids)
What TWO (2) commonly used drugs can result in FALSE-POSITIVE results for KETONES?
CAPTOPRIL and LEVODOPA
How many RBC’s/hpf are required to result in a POSITIVE urine DIP STICK for BLOOD?
1-3 (detects BOTH free Hb and RBC’s)
What can RIFAMPIN, CHLOROQUINE and MYOGLOBIN and INTRAVASCULAR HEMOLYSIS do to the urine DIP STICK?
Cause FALSE-POSITIVE BLOOD readings
What does Vitamin C (ascorbic acid) do to the urine DIP STICK?
It can cause FALSE-NEGATIVE results for RBC and BILIRUBIN detection
Can the urine DIP STICK be used to confirm MYOGLOBINURIA in patients with RHABDOMYOLYSIS?
NO! (have to use separate urine MYOGLOBIN test)
What cells contain the enzyme LEUKOCYTE ESTERASE and how many of them are needed to have the urine DIP STICK result POSITIVE for this?
LEUKOCYTES, 3/hpf
How are Gm NEG bacteria such as E.coli, Klebsiella, Proteus and Pseudomonas detected on urine DIP STICK?
By the presence of NITRITES (conversion of nitrates by the bacteria)
A UTI with what bacteria can result in FALSE NEGATIVE values on urine DIP STICK for NITRITES?
Gm POS bacteria like ENTEROCOCCUS