1.5.0.0 Stag­ing of Chron­ic Kid­ney Dis­ease

Stages 1–2 CKD have been defined by ev­i­dence of kid­ney dam­age (usu­al­ly al­bu­minuria) with eGFR ≥60 mL/‍min/‍1.73 m2, while stages 3–5 CKD have been defined by pro­gres­sively lower ranges of eGFR (14) (Table 11.1). At any eGFR, the de­gree of al­bu­minuria is as­so­ci­at­ed with risk of CKD pro­gres­sion, car­dio­vas­cu­lar dis­ease (CVD), and mor­tal­i­ty (7). There­fore, Kid­ney Dis­ease: Im­prov­ing Glob­al Out­comes (KDIGO) rec­om­mends a more com­pre­hen­sive CKD stag­ing that in­cor­po­rates al­bu­min-‍uria at all stages of eGFR; this sys­tem is more close­ly as­so­ci­at­ed with risk but is also more com­plex and does not trans­la­te di­rect­ly to treat­ment de­ci­sions (2). Re­gard­less of clas­sification scheme, both eGFR and al­bu­minuria should be quan­ti-‍ fied to guide treat­ment de­ci­sions: CKD com­pli­ca­tions (Table 11.2) cor­re­late with eGFR, many drugs are lim­it­ed to ac­cept­able eGFR ranges, and the de­gree of al­bu­minuria may influence choice of an­ti­hy­per­ten­sive (see Sec­tion 10 “Car­dio­vas­cu­lar Dis­ease and Risk Man­age­ment”) or glu­cose-low­er­ing med­i­ca­tions (see below). Ob­served his­to­ry of eGFR loss (which is also as­so­ci­at­ed with risk of CKD pro­gres­sion and other ad­verse health out­comes) and cause of kid­ney dam­age (in­clud­ing pos­si­ble caus­es other than di­a­betes) may also af­fect these de­ci­sions (15).

Table 11.1—CKD stages and cor­re­spond­ing focus of kid­ney-re­lat­ed care

Table_11.1

CKD, chron­ic kid­ney dis­ease; eGFR, es­ti­mat­ed glomeru­lar filtra­tion rate. †CKD stages 1 and 2 are defined by ev­i­dence of kid­ney dam­age (+), while CKD stages 3–5 are defined by re­duced eGFR with or with­out ev­i­dence of kid­ney dam­age (+/-). At any stage of CKD, the de­gree of al­bu­minuria, ob­served his­to­ry of eGFR loss, and cause of kid­ney dam­age (in­clud­ing pos­si­ble caus­es other than di­a­betes) may also be used to char­ac­ter­ize CKD, gauge prog­no­sis, and guide treat­ment de­ci­sions.

*Kid­ney dam­age is most often man­i­fest as al­bu­minuria (UACR ≥30 mg/g Cr) but can also in­clude glomeru­lar hema­turia, other abnor­malities of the uri­nary sed­i­ment, ra­dio­graph­ic abnor­malities, and other pre­sentations.

**Risk fac­tors for CKD pro­gres­sion in­clude el­e­vat­ed blood pres­sure, hy­per­glycemia, and al­bu­minuria.

***See Table 11.2.

Table 11.2—Se­lect­ed com­pli­ca­tions of CKD

Table_11.2

Com­pli­ca­tions of chron­ic kid­ney dis­ease (CKD) gen­er­ally be­come preva­lent when es­ti­mat­ed glomeru­lar filtra­tion rate falls below 60 mL/‍min/‍1.73 m2 (stage 3 CKD or greater) and be­come more com­mon and se­vere as CKD pro­gress­es. Eval­u­a­tion of el­e­vat­ed blood pres­sure and vol­ume over­load should occur at every clin­i­cal con­tact pos­si­ble; lab­o­ra­to­ry eval­u­a­tions are gen­er­ally in­di­cat­ed every 6–12 months for stage 3 CKD, every 3–5 months for stage 4 CKD, and every 1–3 months for stage 5 CKD, or as in­di­cat­ed to eval­u­ate symp­toms or changes in ther­a­py. PTH, parathy­roid hor­mone; 25(OH)D, 25-‍hy­drox­yvi­ta­min D.