Changes in version 1.1.0                        

  - Fixed the Full Age Spectrum (FAS) creatinine equation
    (egfr_fas_cr()) for ages over 40: the creatinine-ratio exponent is
    now correctly -1 (a plain reciprocal) as published in Pottel et al.
    (2016), rather than -0.88. This changes returned eGFR values for
    patients older than 40.
  - egfr_ekfc_cr(), egfr_ekfc_cys(), and egfr_ekfc_cr_cys() gain an
    optional q argument (q_cr / q_cys for the combined equation) to
    supply a population-, assay-, or individual-specific reference Q
    value. The default (NULL) continues to use the built-in EKFC
    reference Q, so existing code is unaffected.

                        Changes in version 1.0.0                        

                        Changes in version 0.1.0                        

  - Initial release.
  - 20 eGFR / creatinine-clearance equations: CKD-EPI 2021 (creatinine,
    cystatin C, combined), CKD-EPI 2009, CKD-EPI 2012 cystatin C, MDRD,
    Cockcroft-Gault, EKFC (creatinine, cystatin C, combined), FAS,
    Lund-Malmoe, Berlin Initiative Study, Schwartz bedside, CKiD U25
    (creatinine, cystatin C, combined, extended), CAPA, and neonatal
    eGFR.
  - Helpers: bsa(), ckd_stage(), and creatinine unit conversion.