TRIPASS XR تري باس

 

Urea standard/serum/diluted urine 0.01 mL

Incubate at the assay temperature for 1 minute and add

Starter reagent (L2) 0.2 mL

Mix well and read the initial absorbance A for the

standard and test after exactly 30 seconds. Read another

absorbance A2 of the standard and test exactly 60 seconds

later. Calculate the change in absorbance ∆A for both the

standard and test.

Sample Start Assay

Pipette into a clean dry test tube labelled Standard (S) or

Test (T):

Addition (S)/(T)

Sequence 37°C / 30°C / 25°C

Working reagent 1.0 mL

Bring to assay temperature and add

Urea standard/serum/diluted urine 0.01 mL

Mix well and read the initial absorbance A1 for the

standard and test after exactly 30 seconds. Read another

absorbance A2 of the standard and test exactly 60 seconds

later. Calculate the change in absorbance ∆A for both the

standard and test.

For Standard ∆AS = A2S – A1S

For Test ∆AT = A2T – A1T

Calculations

 ∆A T

Urea in mg/dL = __________ × 40 ∆A S

Linearity

This procedure is linear upto 250 mg/dL. If values exceed

this limit, dilute the serum with normal saline (NaCL 0.9%)

and repeat the assay. Calculate the value using the proper

dilution factor.

Note

Plasma should not be collected with fluoride or heparin

salts as contamination by ammonia or ammonium salts

lead to erroneous results.

System Parameters

Reaction : Fixed time kin. Interval : 60 sec.

Wavelength : 340 nm Sample

volume

: 0.01 mL

Zero

setting

:  Distilled

Water

Reagent

volume

: 1.00 mL

Incubation

temperature

: 30°C/37°C Standard : 40 mg/dL

Incubated time — Factor :

Delay time : 30 seconds React slope : Decreasing

Read time : 60 seconds Linearity : 250 mg/dL

No. of read : 2 Units : mg/dL

Normal Values (general reference)

Adults: BUN is 8–18 mg%, Urea = 15–40 mg%

Adults over 60 years: May have a little higher values

normally. Low values may be found during pregnancy and

in full-term infants, whereas premature infants may have

slightly higher values than the adult range.

Clinical Relevance

Common Causes of Increased BUN or Uremia

Prerenal

¾ Reduced blood flow to kidney

¾ Shock, blood loss, dehydration

¾ Increased protein catabolism

¾ Crush injuries, burns, fever, hemorrhage into soft tissue

or body cavities, hemolysis.

Renal

¾ Acute renal failure

¾ Glomerulonephritis, malignant hypertension, nephrotoxic drugs or metals, renal cortical necrosis

¾ Chronic renal disease

¾ Glomerulonephritis, pyelonephritis, diabetes mellitus,

arteriosclerosis, renal tubular disease, collagen-vascular

diseases.

472 Concise Book of Medical Laboratory Technology: Methods and Interpretations Post-renal

¾ Ureteral destruction by stones, tumor, inflammation,

surgical trauma, obstruction of bladder neck or urethra

by prostate, stones, tumor, inflammation.

Decreased BUN is Associated with

a. Liver failure.

b. Negative nitrogen balance as may occur in malnutrition, excessive use of IV fluids and physiologic

hydremia of pregnancy.

c. Impaired absorption as in celiac disease.

d. Occasionally in nephrotic syndrome.

e. Overhydration.

Interfering Factors

1. A combination of a low protein and a high carbohydrate

diet cause a decreased BUN level.

2. The BUN is normally lower in children and women

because they have a smaller muscle mass than adult

men.

3. Increased BUN values occur in late pregnancy and

infancy because of increased use of protein.

4. Older people may have an increased BUN when their

kidneys are not able to concentrate urine adequately.

5. Decreased BUN values may normally occur earlier in

pregnancy because of physiologic hydremia.

6. Many drugs can cause increased BUN levels.

7. Drugs that may cause decreased BUN levels include

• Dextrose infusions

• Phenothiazines

• Thymol.

Comments

1. Ammonium oxalate should not be used as an

anticoagulant. Plasma can be used if it is obtained from

EDTA, citrate, potassium oxalate or heparin.

2. If the serum sample is very lipemic, prepare a special

blank tube by adding the phenol color reagent to

the urease before adding the serum. Set the zero

absorbance for the particular sample with this blank.

3. For urgent test__the incubation time can be reduced

to 5 minutes if the water bath temperature is raised to

55–56oC.

4. Plasma or serum preserved with fluoride cannot be

used as this inactivates the enzyme. Urea is stable in

frozen serum for months.

5. Make sure that there is no contamination by ammonia

or heavy metal ions.

6. For a small laboratory, commercially available multi/

monostep kits can be used.

Plasma or Serum Creatinine

Normal Values

Conventional units SI units

Jaffe, manual method 0.8–1.5 mg/dL 70–133 µmol/day

Jaffe, kinetic or enzymatic method

Adult

Female 0.5–1.1 mg/dL 44–97 µmol/L

Males 0.6–1.2 mg/dL 53–106 µmol/L

Eldery May be lower May be lower

Children

Cord blood 0.6–1.2 mg/dL 53–106 µmol/L

Newborn 0.8–1.4 mg/dL 71–124 µmol/L

Infant 0.7–1.7 mg/dL 62–150 µmol/L

Age 1 female ≤ 0.5 mg/dL ≤ 44 µmol/L

Age 1 male ≤ 0.6 mg/dL ≤ 53 µmol/L

Age 2–3 female ≤ 0.6 mg/dL ≤ 53 µmol/L

Age 2–3 male ≤ 0.7 mg/dL ≤ 62 µmol/L

Age 4–7 female ≤ 0.7 mg/dL ≤ 62 µmol/L

Age 4–7 male ≤ 0.8 mg/dL ≤ 71 µmol/L

Age 8–10 female ≤ 0.8 mg/dL ≤ 71 µmol/L

Age 8–10 male ≤ 0.9 mg/dL ≤ 80 µmol/L

Age 11–12 female ≤ 0.9 mg/dL ≤ 80 µmol/L

Age 11–12 male ≤ 1.0 mg/dL ≤ 88 µmol/L

Age 13–17 female ≤ 1.1 mg/dL ≤ 97 µmol/L

Age 13–17 male ≤ 1.2 mg/dL ≤ 106 µmol/L

Age 18–20 female ≤ 1.2 mg/dL ≤ 106 µmol/L

Age 18–20 male ≤ 1.3 mg/dL ≤ 115 µmol/L

Creatinine (Alkaline Picrate Method)

(Courtesy: Tulip Group of Companies)

For the determination of creatinine in serum and urine

(for in vitro diagnostic use only).

Summary

Creatinine is the catabolic product of creatinine

phosphate which is used by the skeletal muscle. The daily

production depends on muscular mass and it is excreted

out of the body entirely by the kidneys.