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Test ID: Galactose-1-phosphate uridyl transferase DBS
Galactose-1-phosphate uridyl transferase DBS
Determination of galactose-1-phosphate uridyl transferase (GALT) activity in blood specimens dried on filter paper to screen newborns for classical galactosemia
Useful For

Screening newborns for classical galactosemia caused by Galactose-1-Phosphate Uridyltransferase (GA LT) deficiency.

 

Method name and description

Semi-quantitative enzymatic assay.

Reporting name

Galactose-1-phosphate uridyl transferase DBS

Clinical information

Galactosemia is an inborn error of metabolism characterized by the inability to metabolize galactose. The most common form is classical galactosemia, which is caused by the inability to transform galactose-1-phosphate into glucose-1-phosphate due to the lack of GALT  activity.   

The genetic disorder is transmitted as an autosomal recessive disease. The mutant gene codes for the synthesis of an altered protein that has little or no transferase activity.

Classic galactosemia  if not diagnosed and treated within the newborn period, it can lead to diarrhea, dehydration, jaundice, hepatic failure, hypoglycemia, cataracts, developmental retardation and death within a few weeks . Sepsis due to Escherichia coli seems to be particularly frequent among galactosemic neonates and is usually the cause of death . Treatment of the disease consists of withdrawal of all foods containing lactose and galactose from the diet.

Reference: GSP Neonatal GALT  kit package insert

 

Aliases

Neonatal Screening Test

Neonatal Screening Testing 

Specimen type / Specimen volume / Specimen container

Specimen type: Whole blood collected from heel prick with direct application onto special Whatman 903 filter paper

Specimen Volume: 5 Circles(spot) if ordered with the whole screening panel. Minimum 3 spot if requested alone i.e., successive collection.                                  

Specimen container: Newborn screening Blood Spot Collection Card 

Collection instructions / Special Precautions / Timing of collection

Collection instructions:

1.Collect blood for newborn screening at 24 hours of age.

Transfused infants :Take the newborn screen sample prior to a blood transfusion. Blood transfusions are known to affect the screening for  galactosemia  because the donor blood. If an infant has a blood transfusion prior to their newborn screen, a repeat  whole blood sample should be obtained 4 to 6 months after their last transfusion.

2.Complete the required patient information on the collection card and ensure that the expiration date of the collection card has not passed.

3.Collect blood from the most medial or lateral portion of the plantar surface of the heel; allow blood to soak through to completely fill each of the preprinted circles; do not apply layers of successive blood drops to the same printed circle; inspect both sides of the collection card to be sure blood is soaked through to the back of the card.

4.Allow blood specimen to air dry for a minimum of three hours on a horizontally level, nonabsorbent, open surface at an ambient temperature of 18 to 25 °C.

5. Fold-over cover provides protection from contamination before blood collection, during specimen transportation and during specimen storage after analysis.

Blood spots must be thoroughly dry before the flap is closed over spots.

6.The collection card/dried blood specimen should be transported to the laboratory with the appropriate tracking documentation and within 24 hours of collection.

Special Precautions

1.Premature infants who are less than 32 weeks of gestational age, screening must be repeated after the infant completes 32 weeks.  

2. Indicate the transfusion status and the date of latest transfusion on the newborn screening collection card.

 

Relevant clinical information to be provided

Complete the required demographic information on the blood spot collection card. 

Transfusion status.

Storage and transport instructions

Transport the specimen at ambient temperature. Newborn screening laboratory specimens have limitations with temperature and humidity conditions between collection and analysis and if the specimens could be subjected to extreme temperature during transit place a cold pack in the specimen transport insulated box.

The specimen must be sent immediately after drying to the laboratory (do not accumulate or batch the specimens). If the blood specimen is taken after midday, or during weekends, the sample should be sent to the laboratory the next working day. Delays in specimen transportation from the collection facility may compromise the integrity of the specimen and could critically impact the newborn.      

Specimen Rejection Criteria

Specimen collected in expired Guthrie card

Insufficient quantity of blood

Errors in patient identifiers.

Specimen spots were damaged or delayed (received after seven (7)  days from the collection date

Specimen appears scratched or abraded.

Specimen appears supersaturated.

Diluted, discolored or contaminated specimens.

Specimen exhibits serum rings.

Specimen appears clotted or layered.

Using white ink on the blood specimen filter paper

Biological reference intervals and clinical decision values

< 2.5 U/dL          Positive

2.5 – 3.5 U/dL    Borderline

>3.5 U/dL           Negative

Factors affecting test performance and result interpretation

Blood transfusions :Specimens from transfused newborns are unsatisfactory because of interference by blood donor RBCs. If possible, the Newborn Screening specimen should be collected before any RBC transfusion. If a specimen cannot be collected before transfusion, another specimen collected at 120 days following the transfusion is required for valid screening,

 

False-positive results can occur when blood is put into an ethylenediaminetetraacetic acid (EDTA) tube prior to being spotted onto filter paper and in infants with G6PD deficiency.

 

Turnaround time / Days and times test performed / Specimen retention time

 

Turnaround time :3 working days.

Days and times test performed: Saturday -Thursday 7:00am-3:00PM

Specimen retention time: Indefinite