Soluble Fms-like tyrosine kinase-1(sFlt-1) and Placental growth factor (PlGF)

Diagnostic Use

sFlt-1 and PlGF are used to determine the ratio of sFlt-1/PLGF. The sFlt-1/PlGF ratio is a biomarker of placental insufficiency and has proven clinical benefit as a rule-out test for pre-eclampsia. Similarly, an elevated ratio is associated with placental insufficiency and may contribute towards a diagnosis of pre-eclampsia in patients with supporting clinical and/or biochemical features of the condition.

Used as a pre-eclampsia marker for women >20 weeks' gestation with:
• Suspected pre-eclampsia
• Isolated or worsening hypertension
• Isolated or worsening proteinuria
• Isolated fetal growth restriction

Department

Endocrinology Lab

Delphic Registration Code

SFPG

Laboratory Handling

Registration

Please contact Endolab on receipt of sample (if within Endolab working hours) who will collect whole blood sample. If received outside of Endolab working hours, please separate and freeze sample.

Separating

Outside of working hours, please separate and freeze sample.

Synonyms

sFlt-1, PlGF

Turnaround Time

3 days

Test Code

SFPG

Specimen Type

• Serum

Specimen Requirements

Tube/Container Type:

Preferred

• Serum (Red Cap)

Preferred if West Coast

• SST II (Gold Cap)

Acceptable

• Serum (Red Cap)
• SST II (Gold Cap)

Preferred Sample Volume (ml)

2

Minimum Sample Volume (ml)

1

No of Samples Required

1

Pre-testing Requirements

Please complete the dedicated sFlt-1/PlGF ratio request form (see Additional Information section for form).
Testing will not take place unless a gestational age is provided. This test is not validated for pregnancies less than 20 weeks’ gestation.

Additional Specimen Information

Turnaround time: 3hours routinely Mon-Fri between 9am-3pm. For urgent requests between 3pm-5pm, please phone the laboratory on x80885 - otherwise testing will take place the next working day. This test is not available out-of-hours.

Once separated, serum is stable for 1 week refrigerated and up to 6 months frozen.

Aliquot Instructions

Sample Type

• Serum

Minimum Volume (ml)

1

Transport to Lab

Chilled (2 - 8 degrees Celsius)
If overnight - Frozen

Additional Referral/Aliquot Information

If analysis is to take place within 48hrs of collection, storage and transport at 2-8°C is acceptable. Serum should be frozen if there is likely to be a delay of 48hrs between collection and analysis.

West Coast: If specimen is unable to be separated, take blood on SST and send chilled to Greymouth Lab. At Greymouth lab freeze serum for transport to CHL.

Interpretation

The sFlt-1/PlGF ratio is interpreted according to gestational age, as per the table below:

Ratio	Gestation
≤38	>20+0	sFlt-1/PlGF ratio is in the normal range.  The probability of developing pre-eclampsia in the next seven days is low.
38-84	20+0 to 33+6	Consistent with placental dysfunction, and a higher risk of adverse pregnancy outcome.
38-109	34+0 to 36+6
≥85	20+0 to 33+6	Consistent with severe placental dysfunction.  In cases of suspected pre-eclampsia, this result is considered confirmatory.
≥110	34+0 to 36+6

 

 

Reference Intervals

Ratio results of >38 will be flagged as abnormal.

See above table for more information on interpretation.

 

References:

Hughes, R et al; The predictive value of the sFlt-1/PlGF ratio in suspected pre-eclampsia in a New Zealand population: A prospective cohort study. Aust NZ J Obstet Gynaecol 2022: 1-8

Test Method

Roche Electrochemiluminescence immunoassay

Non-Funded Test Cost

$332.31 (Exclusive of GST)

Billing Code

2750

Resources

• sFlt-1 PlGF Ratio Request Form (41 KB)

Contact Information

Enquiry Form