The test is carried out using a ;piece of equipment called a Chrono-Log Series 700 Lumi-aggregometer.   A sample of blood is placed in a chamber or cartridge inside the equipment.  A beam of light is shone through the sample.  Particular chemicals are added to each sample. The chemicals are called ‘agonists’ and they are known to cause platelets to stick together, or aggregate.  The test may be repeated a number of times on separate samples with the chemical being  used at increasing concentrations.  When the platelets aggregate more light can pass through the sample and this is used to plot the rate and amount of aggregation.

In addition two other chemicals are added to the samples, called Luciferin and Luciferase.  These are extracted from Fireflies).  If ATP is released from the platelets then the additional chemicals give of light (bioluminescence) that is detected by the machine.

Typical results from Lumi-Aggregometry

How Lumi-aggregometry with ATP-release works

This test focuses on the cause of the bleeding disorder as a means of distinguishing it from the various types of oculocutaneous and ocular albinism.

The purpose of the test is:

1) To determine how well blood platelets stick together (aggregate) and,

2) To infer whether platelet dense granules are present or absent or not secreting ATP.

Normal blood platelets contain dense granules. The dense granules contain chemicals called ADP and ATP.  The test involves stimulating a sample of blood platelets.  If they are normal then they will ‘release’ (secrete) detectable amounts of ATP from their dense granules.  If  they lack dense granules then ATP will be completely or nearly absent from the results of the test


HPS is a difficult syndrome to accurately test for and diagnose.  The severity of the bleeding disorder can vary greatly  between patients.  Also diagnostic tests can have limitations.  For this reason it is best if both Lumi-Aggregometry with ATP-release and a Nucleotide assay are used in combination.

Above: Chrono-Log 700 series Lumi-aggregometer.

Chart showing results of Lumi-Aggregometry for a patient with HPS and normal control. A Chrono-Log 700 Lumi-Aggregometer used to tst for Hermansky-Pudlak Syndrome.

Nucleotide assay

The results from Lumi-Aggregometry with ATP-release may strongly suggest that HPS is a likely diagnosi.

However, it is possible for dense granules to be present but NOT releasing, or secreting,  ATP and ADP. The results could look very similar to those for HPS.  For this reason a Nucleotide assay should be carried out as a ‘double check’.

A nucleotide assay involves preparing a sample of blood platelets and measuring the amounts of ATP and ADP in them.  If a patient has HPS then their should be far less ADP than is found in normal platelets. Also, there should be less ATP than normal but the amount of ATP is still greater than the amount of ADP

Click here to see reference ranges for ATP and ADP in platelets.

There are a number of methods used to test for Hermansky-Pudlak syndrome.  These include:

It is the first two that are mostly widely used in the UK and they are discussed on this page. Details about electron microscopy can be found on another page.  These tests are not available in smaller hospitals because they require specialist equipment and laboratories.  There are a number of larger hospitals throughout the UK which have specialist Comprehensive Care Centres (CCC) where these tests can be carried out (Click here).

Above: Results for HPS patient and normal control.

Top of page

Tests for Hermansky-Pudlak Syndrome in the UK