Directions for collecting and sending samples

Metabolic investigation

Amniotic fluid supernatant

The sample must be collected in the 16th - 18th week of gestation. After the removal of cells by centrifugation, the amniotic fluid supernatant is stored at -20°C and sent frozen on dry-ice. Please contact Dr. Mirjam Wamelink prior to sending amniotic fluid.

Plasma and serum

In general heparinized plasma is preferred to EDTA plasma, citrate plasma, fluoride plasma or serum. Only for the assay of homocysteine EDTA plasma is preferred. After collection, the blood must be centrifuged as soon as possible for 10 minutes at 1800 g. The plasma or serum is stored and sent at -20°C.


A random urine sample (minimum of 10 ml required) can be sent. The urine is stored and sent at  -20°C. In special cases urine can be spotted on filter-paper, dried and send to our laboratory by regular mail. Please contact Dr. Mirjam Wamelink prior to sending samples.

Deproteinated CSF or heparinized blood for lactate and pyruvate

The samples must be collected on ice-water, the sample must be deproteinated as soon as possible after collection (within 15 minutes) in the following way:

  • take 1.0 ml CSF or heparinized blood
  • place it in ice-water
  • add 2.0 ml 5% ice-cold HCLO4 (w/v) and mix thoroughly
  • keep 15 minutes in ice-water
  • centrifuge for 10 minutes at 1800 g
  • store the supernatant at -20°C


Analysis of neurotransmitters and other classes of compounds in CSF have specific sampling conditions, see our CSF protocol .

Enzyme analysis


For biotinidase activity we need 1 ml heparin plasma. After collection, the blood must be centrifuged as soon as possible for 10 minutes at 1800 g. The plasma is stored and sent at -20°C. 

Lymphoblasts or fibroblasts

Sent culture-flask with cells and fully filled with medium at room temperature by courier (door to door service). It is very important that the cells remain at room temperature, also during transportation. It is essential that they are not frozen at any time.


Send 2 ACD or EDTA blood tubes of the patient and 2 tubes of a healthy donor (taken at the same time). If family members are willing to give blood as well, please send 2 additional tubes per family member (parents, brothers or sisters). The tubes should be filled with 10 ml blood of the patient/control person; a total of 20 ml blood of each person. Label the tubes with the name, date of birth and date of sampling. If the patient is very young and it is not possible to obtain 20 ml blood, 10 ml is sufficient. If this is still too much, please contac us.

It is very important that the blood remains at room temperature, also during transportation. It is essential that it is not frozen at any time. The samples should arrive at our laboratory within 48 hours. Please contact Dr. Mirjam Wamelink prior to sending samples.

Moleculair studies  

Blood and DNA 

2 ml EDTA blood or isolated DNA can be sent at room temperature. In the case that an email address is provided we will send a confirmation upon arrival of the package. Please contact  Prof. Gajja Salomons for instructions about molecular prenatal diagnosis.

Directions for sending samples 

Samples must be sent on dry-ice (except for cultured cells or blood for lymphocyte or DNA isolation). Make sure the samples will be kept frozen for a period of 48 hours. Please use our request forms and provide the necessary information like patient data, requesting physician and sample information.

If you have any questions or you require additional information, do not hesitate to contact Dr. Mirjam Wamelink or Prof. Gajja Salomons .

The parcel should be sent in the beginning of the week (i.e. Monday to Wednesday) in order to reduce the risk that samples will arrive in the weekend.

Shipping address:

VU University Medical Center 
Metabolic Laboratory (PK 1X 009)
To: Prof. G.S. Salomons
Goederenontvangst - BS6
Van der Boechorststraat 6
1081 BT Amsterdam
The Netherlands