Calculate eGFR based on cystatin C measurements

Calculate eGFR based on cystatin C measurements

Usage

calc_egfr_cystatin(
  cystatin = NULL,
  cystatin_unit = "mg/L",
  method = c("grubb", "larsson", "hoek", "ekfc", "ckd_epi"),
  unit_out = NULL,
  age = NULL,
  sex = NULL,
  verbose = TRUE
)

Arguments

cystatin

serum cystatin concentration (mg/L)

cystatin_unit

only "mg/L" available

method

eGFR estimation method, choose from "grubb", "larsson", "hoek", "ekfc", "ckd_epi"

unit_out

eGFR output unit, choose from "ml/min", "ml/hr", "l/min", "l/hr", "ml/min/1.73m2". The Larsson method reports absolute eGFR, so it supports all units except "ml/min/1.73m2". The other methods report eGFR per 1.73 m2, so they only support "ml/min/1.73m2". If NULL (default), uses "ml/min" for the Larsson method, and "ml/min/1.73m2" for the others.

age

age, in years. Required for the "ekfc" and "ckd_epi" methods. Optional for the "grubb" method, where it is only used to warn for patients < 18 years of age.

sex

sex, "male" or "female". Required for the "ckd_epi" method.

verbose

verbosity, show guidance and warnings. TRUE by default

Details

The Grubb, Larsson, and Hoek equations were developed with cystatin C assays calibrated before the introduction of the international reference material for cystatin C (ERM-DA471/IFCC), and may be biased when used with results from standardized assays. The EKFC and CKD-EPI equations were developed with standardized assays.

References

• Grubb: Grubb et al., Clinical Chemistry (2005). Uses the equation derived for adults (>= 18 years), without adjustment for sex. Cystatin C measured with DakoCytomation reagents.

• Larsson: Larsson et al., Scandinavian Journal of Clinical and Laboratory Investigation (2004). Uses the equation for the Dade Behring cystatin C calibration.

• Hoek: Hoek et al., Nephrology Dialysis Transplantation (2003). Cystatin C measured with the Dade Behring N Latex assay.

• EKFC: Pottel et al., NEJM (2023). Validated in adults (>= 18 years) only.

• CKD-EPI (2012): Inker et al., NEJM (2012). Developed in adults (>= 18 years) only.

See also

• calc_egfr() for equations using creatinine alone

• calc_egfr_combined() for equations using both creatinine and cystatin C

Examples

calc_egfr_cystatin(1.0)
#> $value
#> [1] 83.93
#> 
#> $unit
#> [1] "ml/min/1.73m2"
#> 
calc_egfr_cystatin(1.0, method = "larsson")
#> $value
#> [1] 77.239
#> 
#> $unit
#> [1] "ml/min"
#> 
calc_egfr_cystatin(1.0, method = "larsson", unit_out = "l/hr")
#> $value
#> [1] 4.63434
#> 
#> $unit
#> [1] "l/hr"
#> 
calc_egfr_cystatin(1.0, method = "ekfc", age = 50)
#> $value
#> [1] 78.58652
#> 
#> $unit
#> [1] "ml/min/1.73m2"
#> 
calc_egfr_cystatin(1.0, method = "ckd_epi", age = 50, sex = "female")
#> $value
#> [1] 75.42894
#> 
#> $unit
#> [1] "ml/min/1.73m2"
#>