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Urea

Test strips for the determination of urea In blood, serum and plasma

Cat. No. Package content
1 3129 99 90 350 60 Test strips
 

Principle

The test strip contains a reaction zone and an indicator zone with a scale. In the reaction zone, urea is specifically splitted into carbon dioxide and ammonia by urease. After diffusion through the gas phase, ammonia colours part of the pH indicator blue. The length of the blue zone depends on

Urea concentration – temperature – reaction time

The temperature and the reaction time are constant so that the length of the blue zone indicates the urea concentraiton directly.
Storage instructions for the test strips
The test strips can be used up to the expiry date if stored in a closed container below 30 °C.
Warnings and precautions
Take note of the necessary precautions for the handling with specimen.
Test strip preparation
The test strips are ready to use.
Specimen
Capillary blood, full blood, serum and plasma (heparin, oxalate and citrate are suitable for obtaining plasma while EDTAand fluoride are not suitable).
Discard contaminated specimens!

Assay procedure

 

Application of the samples

 

By dipping in the test strip* With a pipette
Dip the reaction zone into the liquid to be tested for 2 sec ( do not wet the indicator zone!)  
On removal, wipe off excess liquid against the edae of the vessel.  
Place the test strip in the slider from above (Fig. 1)
  Pipette 1 0 μL of the liquid to be tested onto the reaction zone (distribute evenly!)
Immediate ly push the slider containing the test strip , closed end and reaction
zone first, into the cell (Fig. 2)
 

*When capillary blood is used , ensure that the reaction zone is completely saturated.

Reaction conditions  
Storage of the reaction vessel: Horizontal at constant temperature (avoid direct sunlight)
Temperature: approx. 22oc
Reaction time: normal method 30 min. rapid method 10 min. emergency diagnosis 5 min.

Assessment

Emergency diagnosis

For rough estim ation of the urea concen tration in full blood, the length of the blue zone can be read afte r only 5 min. Lengths of 10 mm or more indicate concentra tions of over 300 mg/dl (50 mmol/L) of urea equivalent to 140 mg/dl of urea-N.

Serum, Plasma

Full blood

Blue zone

Urea

Urea-n

Blue zone

Urea

Urea-n

mm

mg/dL

mmol/dL

mg/dl

mm

mg/dL

mmol/dL

mg/dl

2

50

8

25

2

70

12

35

6

100

17

45

6

140

24

65

10

150

25

70

10

210

35

100

15

220

37

105

15

300

50

140

20

290

48

135

20

390

65

180

Normal method 30 min, approx. 22°c*

Serum, Plasma Full blood
Blue zone Urea     Urea-N Blue zone Urea     Urea-N
mm mg/dL I mmol/l mg/dL mm mg/dL I mmol/l mg/dL
0 14 2   7 0 17 3   8
0.5 17 3   8 0.5 21 4   10
1 19 3   9 1 25 4   12
1.5 22 4   10 1.5 29 5   14
2 25 4   12 2 33 6   15
2.5 28 5   13 2.5 38 6   18
3 31 5   14 3 42 7   20
3.5 34 6   16 3.5 46 8   22
4 37 6   17 4 50 8   23
4.5 41 7   19 4.5 54 9   25
5 44 7   20 5 58 10   27
5.5 48 8   22 5.5 63 10   29
6 51 8   24 6 67 11   31
6.5 55 9   26 6.5 71 12   33
7 59 10   28 7 75 13   35
7.5 62 10   29 7.5 79 13   37
8 66 11   3 1 8 83 14   39
8.5 70 12   33 8.5 88 15   41
9 73 12   34 9 92 15   43
9.5 77 13   36 9.5 96 16   45
10 80 13   37 10 100 17   47
10.5 84 14   40 10.5 104 17   49
11 88 15   41 11 108 18   50
11.5 91 15   42 11.5 113 19   53
12 95 16   44 12 117 20   55
12.5 99 16   46 12.5 121 20   56
13 102 17   48 13 125 21   58
13.5 106 18   50 13.5 129 21   60
14 109 18   51 14 133 22   62
14.5 113 19   53 14.5 138 23   64
15 117 19   55 15 142 24   66
15.5 120 20   56 15.5 146 24   68
16 124 21   58 16 150 25   70
16.5 128 21   60 16.5 154 26   72
17 131 22   61 17 158 26   74
17.5 135 22   63 17.5 163 27   76
18 138 23   64 18 167 28   78
18.5 142 24   66 18.5 171 28   80
19 146 24   68 19 175 29   82
19.5 149 25   70 19.5 179 30   84
20 153 25   72 20 183 30   86
20.5 157 26   73 20.5 188 31   88
21 160 27   75 21 192 32   90
21.5 164 27   77 21.5 196 33   92
22 167 28   78 22 200 33   94
22.5 171 28   80 22.5 204 34   95
23 175 29   82 23 208 35   97
23.5 178 29   83 23.5 213 36   100
24 182 30   85 24 217 36   101
24.5 186 31   87 24.5 221 37   103

*Temperature correction factor

Tempreture (oc) 14 16 18 20 25 27 29 31
Factor 1.2 1.15 1.1 1.05 0.95 0.9 0.85 0.8

 

Dilution limit

If the concentration exceeds the measuring range, the sample mater ial can be diluted 1 + 2 with distilled water. The va lues obtained f rom the conversion table (norma l method ) must then be multip lied by 3.

Reference range

  Urea Urea-N
  mg/dl mmol/l mg/dl
Serum 20 – 40 3.3 – 6.7 10 – 20
Full blood 18 – 36 3.0 – 6.0 9 – 18
Protein intake Normal range urea (serum)
g/kg body weight and day mg/dl

mmol/L

0.5 13 – 23 2.2 – 3.8
1.5 24 – 52 4.0 – 8.7
2.5 31 – 59 5.2 – 9.8

 

Literature

  • 1. Richtarich R, Colombo JP. In: Karger S, Klinischa Chemie. 4th edition. Basal: 1978,p.323
  • 2. F. Dunsbach , Seiffert UB. PrOfung von Merckognost Hamstoff unter Routinebedingungen. Med. Lab. 1974; 11: p. 263-65.
  • 3. Appel W. Medizin 3, 1975; 9: p. 778 – 779

Performance characteristics

Measuring range

The test has been deve loped to determine Urea concentrations up to 180 mg/dL. When values exceed this range samples should be diluted 1+2 with distilled water and the result multiplied by 3.

Specificity

Because of the reaction principle the test is specific for urea.

Limit of detection

The lower limit of detection is 14 mg/dL.

Precision

 

Intra assay
n = 20
Mean
[mg/dl]

SD
[mg/dl]

CV
[%]
Sample 1 24 2.22 9.39
Sample 2 83 3.22 3.87
Sample 3 127 3.04 2.39

 

Intra assay
n = 20
Mean
[mg/dl]

SD
[mg/dl]

CV
[%]
Sample 1 24 1.49 6.31
Sample 2 82 3.01 3.69
Sample 3 130 3.76 2.90

 

Method comparison

A comparison between DiaSys Urea Test strips (y) and the GLDH method (x) using 222 samples gave following results: y = 1.00 x + 2.61 mg/dL; r = 0.981.

Waste management

Please refer to the local legal requirements.

Manufacturer

DiaSys Diagnostic Systems GmbH
Alta Strassa 9 65558 Holzheim Garmany

Evaluation

Scale divisions of the indicator zone: Millimeters with thicke r lines for 0, 5.10, 15, 20 mm. The bottom thick line indicates the zero line. Reading off:Read the transition from blue to yellow at the bottom of the meniscus (arrow in fig. 3).

 

evaluation diagrams