Approach to Chronic Kidney Disease¶

Terra Swanson

Definition of CKD¶

Decreased kidney function or one or more markers of kidney damage for 3 or more months
History of kidney transplant
GFR \< 60; Staging helps risk-stratify pts likely to progress or develop complications of CKD
- CKD IIIa: eGFR 45-60
- CKD IIIb: eGFR 30-44
- CKD IV: eGFR 15-30
- CKD V: eGFR \< 15
Markers of kidney damage
- Albumin/Cr ratio
  - Mild: 0-30 mg/g
  - Moderate: 30-300 mg/g
  - Severe: >300 mg/g
Urine sediment: RBC casts, WBC casts, oval fat bodies or fatty casts, granular casts
Electrolyte derangements
Abnormalities on histology
Structural abnormalities: (cysts, hydronephrosis, scarring, masses, renal artery stenosis)

eGFR \< 45
Persistent urine albumin/creatinine ratio > 300 mg/g
Urine protein/creatinine ratio greater than 500 mg/g
Rapid loss of kidney function (> 30% decline over 4 months)
Hematuria not 2/2 urologic condition or if there are RBC casts on UA
Inability to identify presumed cause of renal dysfunction
Difficult to manage complications (hyperkalemia, anemia, bone-mineral disease, HTN)
Confirmed or presumed hereditary kidney disease (PCKD suspected)

Imbalance of water homeostasis
- As renal mass declines the ability to both concentrate and dilute the urine is impaired
- This manifests as hyponatremia (no end-organ to respond to ADH) and edema
- Treat this with water restriction, diuretics or, eventually, ultrafiltration

Correcting serum bicarbonate to a goal of 23-30 meq/L slows decline in renal function and protects against bone-mineral complications of chronic metabolic acidosis
Can calculate bicarbonate deficit to estimate dose of bicarbonate
If bicarb \< 22, consider:
- Sodium bicarb 650 mg TID (8mEq bicarb per 650mg tablet) up to 5850mg/day (70 mEq or 3 tabs TID)
- Sodium citrate (Bicitra): 1mL = 1 mEq * Careful in cirrhosis since citrate cannot be metabolized
- Baking soda (sodium bicarbonate): 1 teaspoon = 59 mEq HCO3 (careful of Na load)

Goal BP \< 120/80 (Class 2B recommendation) based on SPRINT trial, ACC/AHA 2017, and KDIGO 2021 guidelines
All comers: Diet (e.g. DASH) and lifestyle modifications
CKD without albuminuria or DM:
- Start pharmacotherapy based on ASCVD risk as well as risk for other target organ damage
CKD with moderate to severe albuminuria w/ or w/out DM
- ACEi or ARB titrated to maximally tolerated dose (Class 1B recommendation)
- Thiazide-like diuretics (see CLICK trial for chlorthalidone in advanced CKD)
- Loop diuretics can assist with volume driven HTN in patients with CKD 4-5
HTN in kidney transplant
- CCBs or ARBs are first line (Class 1C recommendation)
Consider stopping ACE-i/ARB if:
- GFR declines >30% over 4 months. Consider evaluation for renal artery stenosis
- K > 5.5 despite low K diet, optimizing dose of diuretics, or adding K-binders

Multifactorial: decreased EPO production, impaired iron absorption, uremic toxins suppressing bone marrow, loss of blood in dialysis circuit, and from GI AVMs
Indications for iron supplementation in non-dialysis patients:
- ALL patients with TSAT \<20% and ferritin \<100 ng/mL
- Patients with Hb \<13 and TSAT \<30% and ferritin \<500 ng/mL
- Can start with PO supplementation (see Anemia section). Reassess iron levels in 1-3 mos; if not appropriately ↑, consider IV iron repletion
Dialysis patients:
- IV Iron preferred method of repletion for HD patients with
  - TSAT \< 20% and ferritin \< 200
  - TSAT \<30% and ferritin \<500 AND with Hb \< 10 OR are on EPO
Dosing: usually administered at HD sessions - 125 mg ferric gluconate at consecutive HD sessions x 8 doses - 100 mg iron sucrose at consecutive HD sessions x 10 doses - Ferumoxytol 510mg at the end of two HD sessions 1-4 weeks apart
Indications for EPO
- Pts w/ Hb \<10 who are not iron deficient (ferritin >500) or who’s anemia persists despite adequate iron repletion

Patients with diabetic nephropathy (T4 RTA) and CKD 5-ESRD are at the highest risk
Strategies to mitigate hyperK
- Low K diet (\< 40-70 mEq/day or 1500-2700 mg/day)
- Loop diuretics
- GI cation exchangers
  - Patiromer (Veltassa): binds K in colon in exchange for calcium
  - Sodium zirconium cyclosilicate (Lokelma): binds K throughout intestine in exchange for sodium and H+
  - Do not use Kayexelate as chronic therapy
Treat metabolic acidosis

Individualize A1C goals. Both the ADA and VA-DOD have guidelines for selecting A1C targets
Treatment:
- Metformin remains first-line but should be dose-reduced based on eGFR
  - eGFR > 45: Maximum daily dose of 2000mg/day (1000mg bid)
  - eGFR \< 45: Reduce max daily dose to 1000mg/day (500mg bid)
  - eGFR \< 30: Discontinue if high risk for volume mediated AKI/chronically ill
- SGLT-2 inhibitors for patients with eGFR > 30 reduces progression to ESRD and death from renal or cardiovascular cause (Evidence: DAPA-CKD, CREEDENCE)
- Finerenone (non-steroidal MRA)- would ask nephrology for help if considering this option since relatively new and increased risk for hyperkalemia. (Evidence: FIDELIO)

Early (CKD3a or 3b) referral to nephrology has better outcomes
Uremic symptoms: fatigue, sleep disturbance, N/V, decreased appetite, dysgeusia, itching, hiccupping
Refractory hyper K
Refractory hypertension
Plot your patient’s eGFR using the graph function in EPIC or CPRS to determine trajectory (normal age-related decline after age 60 is ~ 1ml/min/m2)