Albumin Mass Spectrometry for Familial Dysalbuminaemic Hyperthyroxinaemia (FDH), Serum

Diagnostic Use

Familial Dysalbuminaemic Hyperthyroxinaemia (FDH) is a relatively common (1/10,000) euthyroid condition where variant albumin has increased affinity for thyroxine (T4). The most common FDH albumin variant is 218Arg>His (protein nomenclature).

Dystransthyretin Hyperthyroxinaemia (DTTRH) is another euthyroid condition where variant transthyretin (pre-albumin) has increased affinity for T4.

Presence of FDH and DTTRH variants can result in abnormal thyroid function tests and diagnosis of variants is required to prevent unnecessary intervention in clinically euthyroid patients.

While the most common FDH albumin variant 218Arg>His has a characteristic mass change (decrease of 19 Da), other albumin variants or transthyretin variants may have less specific mass changes and may require genetic testing of Albumin (ALB) or transthyretin (TTR) genes for confirmation of whether the variant is clinically significant. If this is needed, EDTA whole blood will be required for DNA extraction and testing.

Department

Specialist Biochemistry

Delphic Registration Code

MOLP

Laboratory Handling

Test Adds

Chilled (2 - 8 degrees Celsius)

Constituent Tests

• Familial Amyloidotic Polyneuropathy (FAP): TTR gene analysis

Synonyms

Albumin variants
FDH
Pre-albumin variants
Transthyretin variants
Dystransthyretin Hyperthyroxinaemia
DTTRH

Turnaround Time

6 weeks

Test Code

MPST

Specimen Type

• Serum
• Plasma
• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• Serum (Red Cap)

Acceptable

• Serum (Red Cap)
• SST II (Gold Cap)
• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1

Minimum Sample Volume (ml)

0.5

No of Samples Required

1

Interferences

Gross haemolysis

Additional Specimen Information

Confirmation of a variant by DNA sequencing of albumin and/or transthyretin genes can be performed in addition to mass spectrometry analysis. Ideally, one 4 mL EDTA blood tube would also be collected and transported at room temperature for DNA extraction if needed following analysis by ESI TOF LCMS.

Aliquot Instructions

Sample Type

• Serum
• Plasma
• Whole Blood

Minimum Volume (ml)

1

Transport to Lab

If overnight - Chilled (2 - 8 degrees Celsius)

Additional Referral/Aliquot Information

Confirmation of a variant by DNA sequencing of albumin and/or transthyretin genes can be performed in addition to mass spectrometry analysis. Ideally, one 4 mL EDTA blood tube would also be collected and transported at room temperature for DNA extraction if needed following analysis by ESI TOF LCMS.

Test Method

Serum (or plasma) is analysed by direct injection ESI time-of-flight (TOF) mass spectrometry. Deconvolution of multiply charged ions enables assessment of albumin and transthyretin. Mass changes are used to identify albumin and transthyretin variants.

Genetic testing to confirm variants is performed by amplifying patient DNA using polymerase chain reaction, followed by bidirectional fluorescent DNA sequencing. Sequencing data is compared to the reference sequence of ALB or TTR and MS data to identify and/or confirm a variant.

Non-Funded Test Cost

$150 (Exclusive of GST)

Depending on the abnormality detected by mass spectrometry, genetic analysis may also be required.

Contact Information

Enquiry Form

Contact Information

Enquiry Form