Test Directory

This test is used for the measurement of Interleukin-2 Soluble Receptor α (sIL-2Rα) levels in serum.

Specimen Type: Serum

Collection Container: Gold Top, Serum Separator

Alternate Collection Container: Red Top, Plain

Desired Specimen Volume: 0.5 mL

1. Collect specimen in gold top, serum separator tube via venipuncture

1. Separate serum from cells.
2. Transfer 0.5 mL of serum to a LabCorp PP transpak frozen purple tube.
3. Freeze immediately.

Transport to the laboratory frozen. 

• Thawed specimen

See patient report.

sIL-2Rα level is only one out of eight criteria of which five have to be met to make a diagnosis. The combination of these clinical and laboratory criteria should warrant sufficient specificity. In order to reach a high specificity close to 100%, levels >10,000 U/mL are required.

The clinical presentation of HLH can have considerable overlap with other inflammatory conditions. A normal or only modestly elevated sIL-2Rα, despite extremely elevated ferritin, suggests disseminated infection in the context of primary immunodeficiencies, especially in an infant.

Although high levels of sIL-2Rα may be suggestive of sarcoidosis, there is substantial overlap in patients with other interstitial lung diseases.

• IL-2 sRα