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Urine dipstick Flashcards

1
Q

what is definition pyuria

A

> 10 WBC per mm3

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2
Q

UTI definition
MSU
SP aspirate

A

more than 10 to 5 CFU per ml or more than 5 bacteria per HPF

any bacteria in SP aspirate

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3
Q

dipstick haematuria definition

A

more than 3 RBC per HPF

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4
Q

leucocytes false positive reasons 3

A

rifampicin
glucosuria
nitrofurantoin

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5
Q

how is haematuria detected

A

oxidation of a chromagen by peroxidase activity of hb on a substrate orthotolidine
colour change on strip compared to known standards

The chromogen indicator on the dipstick orthotolidine is a peroxidase substrate
When haemoglobin comes into contact with orthotolidine an oxidation reaction takes place resulting in colour change blue colour of indicator

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6
Q

false negative cause of haematuria

A 
due to red cell lysis in transit from community
vitamin c (reducing agent)
captopril
ph less than 5.1
proteinuria
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7
Q

false positive haematuria

A 
myoglobinuria
bacterial peroxides
povidone 
menstruation
exercise dehydration
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8
Q

definitiion of NVH

A

more than 3 RBC per HPF according to AUA in 2 of 3 samples

or more than 5 RBC per microlitre in nephrology

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9
Q

prevalence of NVH

A

8% of women and 2.5% men working age

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10
Q

haematuria screening studies

A

britten 1992

16-20% of dipstick will have NVH in men 50-60 of which 5-8% will have cancer

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11
Q

risk of UC in patients with negative investigations for VH

A

near zero in first 6 years

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12
Q

incidence of cancer in NVH

A

70% of NVH no abnormality found

5% yield

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13
Q

Prince study 2014

A

5000 bladder cancer patients compared with >20000 matched controlled to estimate PPV
PVV was highest for wcc and dysuria

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14
Q

any haematuria risk of UC

A

10%

with 7.5% stone disease

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15
Q

VH risk Urinary tract cancer

A

13%

9.2% stone disease

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16
Q

NVH risk urinary cancer

A

3% of which 0% UTUC

4.3% stone disease

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17
Q 
causes urine colour
orange
red
green blue
brown
A

sulfasalazine orange
red - haematuria, rifampicin, chronic lead poisoning
green blue - methylene blue, metronidazole, nitrofurantoin
brown - urobilinogen, porphyria, metronidazole, nitrofurnatoin

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18
Q

chromogen indicator for hb name
colour change
time taken

A

orthotolidine
is a peroxidase substrate
to green
wait 60 seconds

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19
Q

dipstick haematuria
+
++
+++

A 
10
25
50
150
250
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20
Q

leucocyte test on dipstick

colour change

A

leucocyte esterase activity of neutrophils
hydrolysis
released by WBC neutrophils
hydrolysis of substrate on dipstick to produce indoxyl which oxidizes diazonium salt chromogen
change to violet

Enzyme causes hydrolysis of an indoxyl carbonic acid ester - the substrate on dipstick – to indoxyl which in turn oxidizes a diazonium salt chromogen on dipstick to produce colour change

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21
Q

substrate name for wcc

A

indoxyl carbonic acid ester
diazonium salt chromagen
wait 2 minutes

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22
Q

how to do urine dipstick

A

. Check the expiry date of the urinalysis dipstick.

  1. Remove a dipstick from the container whilst avoiding touching the reagent squares.
  2. Replace the container lid to prevent oxidisation of the remaining dipsticks.
  3. Insert the dipstick into the urine sample, ensuring all reagent squares are fully immersed.
  4. Remove the dipstick immediately and tap off any residual urine using the edge of the container, making sure to hold the dipstick horizontally to avoid cross-contamination of the reagent squares.
  5. Lay the dipstick flat on a paper towel.
  6. Use the urinalysis guide on the side of the testing strip container to interpret the findings. Different reagent squares on the strip need to be interpreted at different times, so ensure you interpret the correct test at the appropriate time interval (e.g. 60 seconds for protein).
  7. Once you have interpreted all of the tests, discard the strip into the clinical waste bin along with your PPE.
  8. Wash your hands.
23
Q

time to interpret wcc

24
Q

false positive WCC

A

contanmination eg vaginal discharge

25
false negative WCC
``` glucosuria rifampicin nitrofurantoin old specimen (leucocyte lysis) dehydration vit c urobilinogen ``` left too long white cell lysis read under 2 mins
26
number of wcc detected for positive
>10 wbc per hpf
27
wcc sens and sepc
sen 70-90% spec 40-80% PPV 50% NPV 90% combined 75-80% 80-90% spec nitrites spec 92%-100% sensitivty 30-70%
28
``` nitrates test react with what reagent to form what bacteria convert colour change reagent name ```
``` most bacteria convert nitrates to nitrities not usually present in urine react with aromatic amine reagent to form a diazonium salt colour change pink urinary nitrates to nitrites ``` Nitrites react with aromatic amine reagent on the dipstick to form a diazonium salt The salt then reacts with hydroxybenzoquinolone to form a pink coloured azo dye (Griess reaction)
29
time taken nitrate test | colour change
60 second | to pink
30
why need close diptstick container
nitrate reagnet sensitive to air exposure | containers should be closed
31
false negative nitrite test
may miss grame positive inc pseudonomas | short transit time diuresis less than 4 hours
32
nitrates sens and spec
sens 20-40% spec 90-100% PPV 80% NPV 80%
33
combination leuc and nitrate test sens and spec
more spec but less sensitivie than each test alone sens 75%-84% spec 82-98%
34
nitrates false negative
``` gram positive transit time <4 hours urine in bladder elevated urobilinogen vitamin c ph less than 6 elevated SG ```
35
protein test reagent colour change
bromophenol blue sensitive for albumin to blue green colour
36
usual permeability for proteins
less than 20kD only peremeable
37
proteinuria definition more than mg per day
more than 150mg per day i.e. 10-20mg per dl
38
protein dipstick plus number to amount of protein
1+ = 30mg protein per dl and is considered positive 2+ 100 3+ 300 4+ to 1000 mg per dl
39
RTA unable to acifidy to type I type II
The inability to acidify urine to a pH of less than 5.5 despite an overnight fast and administration of an acid load is the hallmark of RTA. In type I (distal) RTA, the serum is acidic but the urine is alkaline, secondary to an inability to secrete protons into the urine. Type II (proximal) RTA is characterized by an inability to reabsorb bicarbonate. This situation initially results in alkaline urine, but as the filtered load of bicarbonate decreases, the urine becomes more acidic.
40
``` urinary crystals coffin lid envelope barrel shaped hexangonal ```
coffin lid - MAP envelope calcium oxalate hexagonal cystine uric acid diamond or barrel shaped
41
urine ph normal range
5.5 to 6.5
42
when suggest stones with urine ph
ph >7.5 with UTI
43
why alkaline urine associated with CAP stones
urease bacteria catylyses urea to co2 and ammonia, which raises urinary PH, alkalinity causes precipitation of calcium mag ammonium phosphate staghorn stones
44
how much protein excreted daily
80 to 150mg excreted daily
45
protein dipstick test substance
tetrabromophenol turns blue with albumin more than 20mg/dl
46
protein dipstick test substance
tetrabromophenol turns blue with albumin more than 20mg/dl
47
false negatives protein test
bence jones dilute urine high PH
48
false negatives protein test
bence jones dilute urine high PH
49
glucose normal conditions renal reabsorption threshold
180mg/dl
50
urine dipstick glucose reaction
double oxidation of glucose results in colour change
51
``` preparation MSU how much pass first before mid stream circumcised uncirmcumcised women ```
circumcised no prep, pass more than 100mls then collect urine uncirmcumcised retract , wash glans soap then void as above women retract labia, clean periurethral are soap, provide sample
52
preparation sample microscopy
5-10mls cetrifuged for 5 mins
53
IDENTIFY study
>11,000 patients All cancers Any Haematuria 20% VH 26% NVH 6% No bladder cancer in NVH under 35 no UTUC in NVH under 60
54
items on urine dipstick
``` leuc 2 mins nit urobilinogen protein ph blood SG 45 seconds ketones bilirubin 30 seconds glucose 30 seconds ```

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