bsa                     Body surface area (BSA)
ckd_stage               KDIGO CKD stage from eGFR
convert_creatinine      Convert serum creatinine between mg/dL and
                        umol/L
egfr_bis_cr             Berlin Initiative Study (BIS1) creatinine eGFR
                        (2012)
egfr_capa               CAPA paediatric cystatin C eGFR (2014)
egfr_ckdepi_cr_2009     CKD-EPI 2009 creatinine eGFR (with race
                        coefficient)
egfr_ckdepi_cr_2021     CKD-EPI 2021 creatinine eGFR (race-free)
egfr_ckdepi_cr_cys_2021
                        CKD-EPI 2021 combined creatinine + cystatin C
                        eGFR (race-free)
egfr_ckdepi_cys_2012    CKD-EPI 2012 cystatin C eGFR
egfr_ckdepi_cys_2021    CKD-EPI 2021 cystatin C eGFR (race-free)
egfr_ckid_u25_cr        CKiD U25 creatinine eGFR
egfr_ckid_u25_cr_cys    CKiD U25 combined creatinine + cystatin C eGFR
egfr_ckid_u25_cr_extended
                        CKiD U25 extended creatinine eGFR (to age 30)
egfr_ckid_u25_cys       CKiD U25 cystatin C eGFR
egfr_cockcroft_gault    Cockcroft-Gault creatinine clearance
egfr_ekfc_cr            EKFC creatinine eGFR (2021)
egfr_ekfc_cr_cys        EKFC combined creatinine + cystatin C eGFR
                        (2023)
egfr_ekfc_cys           EKFC cystatin C eGFR (2023)
egfr_fas_cr             Full Age Spectrum (FAS) creatinine eGFR
egfr_lund_malmo         Lund-Malmoe Revised creatinine eGFR (2011)
egfr_mdrd               MDRD 4-variable eGFR (IDMS-standardised)
egfr_neonatal           Neonatal creatinine eGFR (2022)
egfr_schwartz           Schwartz bedside paediatric eGFR (2009)
gfr_bsa_adjust          Normalise or de-normalise GFR using body
                        surface area
