Renal Pharmacy Group Beginners Lectures 2018 Introduction to the renal patient pathway

Stages of CKD CKD stage Comment eGFR (ml/min/1.73 m2) 1 Kidney damage with normal or  GFR 90ml/min 2 Kidney damage with mild  GFR 60-89ml/min 3A Kidney damage with Moderate  GFR 45-59ml/min 3B 30-44ml/min 4 Severe  GFR 15-29ml/min 5 Established renal failure <15ml/min (or dialysis)

Acute Kidney Injury Network (AKIN) Staging Stage Serum creatinine (SCr) criteria Urine Output criterai 1 Increase in SCr ≥ 26µmol/l within 48hrs Or Increase ≥ 1.5 – 1.9 x reference SCr < 0.5ml/kg/hr for more than 6 consecutive hours 2 Increase ≥ 2 - 2.9 x reference SCr < 0.5ml/kg/hr for more than 12 consecutive hours 3 Increase ≥ 3x reference SCr Increase ≥ 354µmol/l Commenced on renal replacement therapy (RRT) irrespective of stage < 0.3ml/kg/hr for more 24 hours Anuria for 12 hours

Cockcroft and Gault Equation Provides calculated creatinine clearance, which is a surrogate marker of GFR CrCl (ml/min) = F x (140-age) x wt (kg) serum creatinine (mol/L) F = 1.04 Female = 1.23 Male Overestimates in obese and underestimates in small patients – Use actual body weight if BMI<18.5, IBW if BMI 18.5-24.9 or adjusted body weight if BMI>25 Not accurate in rapidly changing renal function Most drug dosages based on this equation Only validated in Caucasians

The 4 variable Modification of Diet in Renal Disease (MDRD) Equation Provides estimated GRF (eGFR) normalised to BSA of 1.73m2 Best mathematical estimation – esp CKD stages 3, 4 & 5 eGFR = 175((serum creatinine (mol/l)/88.4)-1.154) x (age (years)-0.203) x 0.742 if female and x 1.21 if African American or African Caribbean eGFR units = ml/min/1.73m2 Main advantage – no need for weight Endorsed by UK CKD guidelines Validated in Caucasians and African Americans In patients with near normal renal function this equation can underestimate renal function

CKD-EPI calculation NICE in 2014 suggested that the CKD-EPI equation should be used to estimate GFR using creatinine to confirm or rule out CKD if eGFR using MDRD is 45-59 and no proteinuria on two occasions There are two CKD-EPI equations, one using creatinine and one using cystatin-C GFR = 141 × min(Scr/κ, 1)α × max(Scr/κ, 1)-1.209 × 0.993Age × 1.018 [if female] × 1.159 [if black] where: Scr is serum creatinine in µmol/L, κ is 61.9 for females and 79.6 for males, α is -0.329 for females and -0.411 for males, min indicates the minimum of Scr/κ or 1, and max indicates the maximum of Scr/κ or 1 The equation does not require weight because the results are reported normalized to 1.73 m² body surface area, which is an accepted average adult surface area.

Comparison of estimates of GFR for two patients with the same serum creatinine CrCl – Using Cockcroft and Gault (ml/min) eGFR – Using MDRD eGFR calculator (ml/min/1.73m2) Young, muscular, black male (20yr, 90kg) Serum creatinine 110mol/l 120ml/min >90ml/min/1.73m2 (normal renal function) Thin, elderly female (75yr, 50kg) Serum creatinine 110 mol/l 29ml/min 40ml/min/1.73m2 (stage 3 CKD)

Ways that patients may present to the renal team AKI – no previous CKD, patient recovers or continues with degree of CKD Acute on chronic – unknown CKD presents with AKI GP finds an increase in creatinine and refers to nephrology clinic – could be AKI or CKD Nephrology clinics follow up all patients with CKD

Low clearance clinic Patient monitored and symptoms controlled Assessed for suitable type of RRT Slowing of time to RRT

Types of RRT HD PD Transplant Conservative management

Peritoneal dialysis Haemodialysis Transplant Pre dialysis clinic

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