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Flashcards in Diagnostics Deck (17)
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1
Q

How is a general urinalysis carried out?

A
  1. Cleanse external genitalia to avoid contamination
  2. Collecting urine mid-stream
  3. Centrifuge urine at 3,000 rpm/min for 3-5 minutes
  4. Pour supernatant into separate tube and re-suspend sediment
  5. Prepare slide with sediment
  6. Analyze supernatant and sediment
2
Q

What things can a dipstick check? If positive, what can it indicate? (7)

A
  1. pH (normal = 5-6.5)
    - > 7.5-8.0 indicates UTI with urea-splitting organism
  2. Leukocytesterase
    - Presence indicates leukocytes in urine
  3. Glucose
    - Presence indicates high plasma glucose or proximal tubular defect
  4. Ketones
    - Present indicates ketoacidosis
  5. Proteins (bilirubin, urobilinogen, peroxidase)
    - Presnece indicates kidney damage
  6. Nitrite
    - Presence indicates gram-negative bacteria
  7. Heme
    - Presence indicates blood in urine, intravascular hemolysis, or rhabdomyolysis
3
Q

What is a “cast” in the context of urine microscopy. What does it indicate?

A

Precipitated protines and cells forming within the tubular lumen of the kidney

  • If present, this indicates possible urinary stasis
  • If composed of white blood cells, this indicates pyelonephritis
  • Hyaline casts indicate they were made in the lumen of the nephron
  • Granular casts indicate a proteinuric condition
  • Waxy casts indiate the cells are generating (time?)
4
Q

What is specific gravity of a urine sample and what does high or low indicate?

A

A parameter based off the concentration of excreted molecules in urine and used to evaluate kidney function.

  1. Increase = > 1.030
    - May indicate dehydration, diarrhea, emesis, excess sweating, UTI, glucosiuria, renal artery stenosis, hepatorenal syndrome, decreased blood flow (heart failure), or excess ADH
  2. Decrease = <1.000
    - May indicate renal failure, pyelonephritis, diabetes insipidus, acute tubular necrosis, interstitial nephritis, psychogenic polydipsia
5
Q

What can be found on a urine microscopy test and what do things indicate?

A
  1. Red blood cells
  • Presence as a cast indicates glomerulonephritis or vasculitis
  • Presence as fragments indicates glomerular bleeding
  • If round and uniform, or if clots, this indicates they have an extra-renal origin
    2. White blood cells
  • Presence indicates infection or inflammation
  • If present as a cast, indicates acute pyelonephritis or tubulointerstitial disease
    3. Protein
  • If present >500 mg/day, indicates glomerular or tubular lesion
  • If present >3,000 mg/day, indicates a glomerular lesion
    4. Epithelial cells
  • If present in a cast, indicates kidney origin
    5. Lipids
  • If present, indicates glomerular disease and nephrotic syndrome
    6. Crystals
  • Indicates cystinuria if cystine crystals
6
Q

What is a normal blood urea nitrogen (BUN) to creatinine ratio in the kidneys?

A

5-20:1

7
Q

What are 9 ways to measure GFR?

Which 2 are most widely used equations?

What is the most widely used clinically?

Which is the gold standard?

A
  1. Serum creatinine
  2. Cockcroft-Gault formula
  3. Cystatin c
  4. Modification of Diet in Renal Disease equations
  5. CKD-EPI equations
  6. 24-hour urine creatinine clearance
  7. 24-hour mean urea and creatinine
  8. Iothalamate (and other radioisotopes)
  9. Inulin clearance methods

Most common = MDRD and CKD-EPI

Clinically common = serum creatinine

Gold standard = inulin clearance

8
Q

What is the RIFLE criteria? R

A

R = risk = serum creatinine increased 1.5x = <0.5 mL/kg/h urine output for 6 hours

I = injury = serum creatinine increased 2.0x = <0.5 mL/kg/h urine output for 12 hours

F = failure = serum creatinine increased 3.0x (or 355+ uM with acute rise >44 uM) = <0.3 ml/kg/h urine output for 24 hours (or anuria for 12 hours)

L = loss = persistent acute failure, complete loss of kidney function longer than 4 weeks

E = end-stage renal disease = longer than 3 months (CKD)

9
Q

Define the following renal function tests:

  1. Urine albumin creatinine ratio
  2. Urine protein
  3. Serum creatinine
  4. Serum albumin
  5. BUN

Which is unaffected by variation in urine concentration / protein levels in the blood

A

1 unaffected

  1. A ratio of how much albumin (mg) per creatinine (g) is present in the urine
  2. A measure in mg of how much protein is in the urine over 24 hours
  3. A measure of how many uM of creatinine is in a litre of blood
  4. A measure of how much albumin is present in a litre of blood
  5. A measure of how much urea nitrogen is present in a litre of blood
10
Q

Amniocentesis:

  1. Define
  2. What tests may it include?
  3. What does it screen for?
  4. When is it done?
  5. What is its risk?
  6. What are its benefits?
A
  1. Sampling of amniotic fluid, about 1 cc per week of GA) using a hollow needle inserted into the uterus
  2. QFPCR, AFP levels, Karyotype, Microarray
  3. Trisomy 13/18/21, XXY, X0, spina bifida, specific mutations
  4. >15/16 weeks gestation
  5. Risk of miscarriage 1/1000
  6. Outpatient procedures with no freezing
11
Q

Chorionic Villus Sampling:

  1. Define
  2. What tests may it include?
  3. What does it screen for?
  4. When is it done?
  5. What is its risk?
A
  1. Tissue sampling from the chorion villi of the fetal placenta, either transabdominally or transcervically
  2. QFPCR, karyotype, microarray
  3. Numerous genetic disorders
  4. Week 11-14
  5. Risk of miscarriage of 1/100
12
Q

First Trimester U/S - what is the normal progression of visualizing fetal components?

A
  1. Chorionic Sac (bhCG 6,000)
  2. Yolk Sac (bhCG 7,000)
  3. Embryo (bhCG 11,000)
  4. Fetal movement (week 7)
  5. Fetal cardiac activity (week 8)
  6. Normal bowel herniation (week 8)
  7. Arms and legs (week 8)
13
Q

What are 4 things that must always be commented on in a fetal U/S

A
  1. Gestational age (crown-rump length)
  2. Fetal number
  3. Nuchal translucency
  4. Non-pregnancy anomalies to uterus, adnexa, and cul-de-sac
14
Q

What are 7 features examined in a second trimester U/S?

What are 2 additional features examined in a third trimester U/S?

A

Second Trimester:

  1. Amniotic fluid volume
  2. Placental location
  3. Umbilical cord (# of vessels, placental insertion, fetal insertion)
  4. Cervical length
  5. Anatomic suvery (18-22 weeks)
  6. Gestation age
  7. Uterus/adnexa

Third trimester: (the above plus)

  1. Estimated fetal weight (femur length, abdominal circumference, biparietal diameter)
  2. Anatomical survey for new anomalies
15
Q
  1. What is the glucose challenge test?
  2. How is it done?
  3. What is a positive result?
A
  1. A test used to determine risk of gestational diabetes
  2. Administer 50 grams of glucose; take blood at time 0 and 1 hour
  3. >7.8 mmol/L after 1 hour
16
Q
  1. What is the glucose tolerance test?
  2. How is it done?
  3. What is a positive result and what does this mean?
  4. When is it done?
A
  1. A test used to determine risk of gestational diabetes after a positive GCT
  2. Fast for 8-12 hours, administer 75-100 grams of glucose; take blood at time 0, 1, 2, and 3 hours
  3. >5.3 mmol/L while fasting, >10mmol/L at 1 hour, >8.5 mmol/L at 2 hours, or >7.8 mol/L at 3 hours –> one of these means you have gestational diabetes
  4. If there is a positive GCT
17
Q

When is GCT/GTT done?

A

Offered to every woman around 24-28 weeks

Done earlier than 24-28 in women with GD risk factors (and then AT 24-28 if negative)

Risk factors for GD include BMI >30, previous birth >9.9lb, family history of DM, prior GD, 35+ years, Aboriginal, Hispanic, South Asian, Asian, African