R-ISS Stage Calculator (Multiple Myeloma)
Use this tool to estimate ISS stage and R-ISS stage from common baseline data.
Educational use only. This calculator does not replace physician judgment, pathology review, or guideline-based care.
What is the R-ISS calculator?
The R-ISS calculator helps classify multiple myeloma into prognostic groups using the Revised International Staging System. It combines standard ISS lab values with two extra risk features:
- LDH level (normal vs elevated)
- High-risk cytogenetics (present vs absent)
This provides a more complete risk picture than ISS alone and is commonly used in clinical discussions, treatment planning, and trial stratification.
Inputs used in this calculator
1) Beta-2 microglobulin (mg/L)
A key marker in ISS staging. Higher values generally reflect higher disease burden and/or renal impact.
2) Albumin (g/dL)
Used with beta-2 microglobulin to assign ISS Stage I, II, or III.
3) LDH status
Elevated LDH is considered an adverse feature in R-ISS classification.
4) High-risk cytogenetics
Typically includes abnormalities such as del(17p), t(4;14), or t(14;16), depending on local reporting standards and guidelines.
How the staging logic works
ISS staging
- ISS I: beta-2 microglobulin < 3.5 mg/L and albumin ≥ 3.5 g/dL
- ISS III: beta-2 microglobulin ≥ 5.5 mg/L
- ISS II: all other combinations
R-ISS staging
- R-ISS I: ISS I + normal LDH + no high-risk cytogenetics
- R-ISS III: ISS III + (elevated LDH or high-risk cytogenetics)
- R-ISS II: everyone else
How to use this result
Use the calculator output as a structured summary to support conversations with hematology/oncology teams. It is most useful when interpreted together with:
- Patient age, performance status, and frailty
- Renal function and comorbid conditions
- Bone marrow findings and imaging
- Current treatment goals and response depth (e.g., MRD context)
Important limitations
R-ISS is helpful, but it does not capture every prognostic factor. Newer systems and genomic tools may refine risk estimates further. Also, outcomes depend heavily on treatment era and access to modern therapies.
If you are a patient or caregiver, always review results with your care team before drawing conclusions.