Hyaluronic acid (HA or hyaluronan) is a high molecular weight polymer belonging to the glycoaminoglycan family. It is synthesized on the cytoplasmic membranes of mesenchymatous cells, notably fibroblasts.

It is broken down by endothelial cells in the hepatic sinusoids and clearance vi a the kidneys is negligible.

The assay for hyaluronic acid is based on a radioimmunological method.

Given the different concentrations, the sample type should be clearly indicated on the order.

HA levels have been extensively measured in patients with chronic liver disease, namely primary biliary cirrhosis and chronic hepatitis C. There is a clear correlation between HA level and the histological grade of the fibrosis.
As a predictor for cirrhotic progression, HA seems to be more sensitive than the Procollagen III peptide.

A mesothelioma is a primary tumor derived from a mesothelial cell in the pleural, peritoneal or pericardial cavity. Exposure to asbestos is the main risk factor for malignant forms of this type of tumor (asbestosis which tends to develop 30 to 40 years after exposure).
Malignant mesothelioma accounts for 2 to 3 % of all pleural cancers.

This disease is not always easy to diagnose, despite the usefulness of immunohistological techniques. A high HA level in the pleural fluid is a suggestive element, either on its own or combined with ACE levels and cytokeratin makers (TPA and above all Cyfra21-1).
All three of these tests are available (on serum) for the monitoring of patients who are at high risk of developing asbestosis..