COVID-19 and Cytokine Storm/Cytokine Release Syndrome (CRS)

May 6, 2020

COVID-19 and Cytokine Storm/Cytokine Release Syndrome (CRS)

During this COVID-19 crisis, coders are beginning to see the providers document cytokine storm as a secondary diagnosis in patients who have been diagnosed with a primary diagnosis of COVID-19.

Some of the acutely ill COVID-19 patients are developing a cytokine storm which is a Cytokine Release Syndrome (CRS). The sickest patients are the ones who have CRS that can lead to the patient developing secondary hemophagocytic lymphistiocytosis (sHLH) which then causes the patient to develop acute respiratory distress syndrome (ARDS).1

CRS “is caused by a large, rapid release of cytokines into the blood from immune cells” “Cytokines are immune substances that have many different actions in the body.” In some patients, excessive or uncontrolled levels of cytokines are released which then activate more immune cells, resulting in hyperinflammation. It is the overreaction of the immune system.

Coders and CDI Specialists should be very careful when querying the provider for clarification of cause of the signs/symptoms and/or clinical indicators for appropriate code assignment. 1,2 The symptoms of CRS can mimic other conditions.

Cytokine storms can be seen in the below conditions which have similar pathophysiology but have very different treatment options. Therefore, it is imperative to capture the conditions correctly through coding.

  • Sepsis
  • Non-infectious SIRS
  • Macrophage activation syndrome (MAS)
  • Secondary hemophagocytic lymphohistiocytosis

Possible Signs/Symptoms of CRS:

  • Trouble breathing
  • Low blood pressure
  • Rapid heart rate
  • Fever
  • Headache
  • Nausea
  • Rash
  • Multi-organ dysfunction – in severe cases

Possible Laboratory Clinical Indicators of CRS:

  • Elevated serum ferritin2
  • Markedly increased interleukin-6 (IL-6)2
  • High levels of C-reactive protein2
  • Elevated blood nitrogen levels5
  • Elevated D-dimer5

Coding Guidance:

Currently, as of April 1, 2020, neither CRS nor cytokine storm can be indexed in the ICD-10-CM code book.

Per the AHA Coding Clinic for ICD-10-CM/PCS, Second Quarter 2019 Pages 24-25, and First Quarter 2020 Page 37, with there not being a specific code for CRS and it cannot be indexed in the code book, coders must follow the ICD-10-CM Official Guidelines for Coding and Reporting Section I.B.15 Syndromes where there are instructions to code the manifestations of the syndrome based on physician documentation. Any additional manifestations that are not typically integral to the condition may also be assigned if the condition does not have its own unique code. 4

NOTE: Changes to the official coding guidelines and rules beyond April 1, 2020 will render the Coding Guidance educational content invalid for future educational purposes.

Lorrie Strait, RHIT, CCS

Manager HIM Services, Excite Health Partners


  2., April 8, 2020
  4. AHA Coding Clinic for ICD-10-CM/PCS, Second Quarter 2019 Pages 24-25, and First Quarter 2020 Page 37
  5. Merck Manual,