PHRM 802 Chronic Kidney Disease and End Stage Kidney Disease

Chronic Kidney Disease

Long term kidney disease, happens over lifetime and leads to end stage kidney disease

• Diabetes mellitus and hypertension are major causes, Polycystic Kidney Disease is another cause

CKD staging by KDIGO

Based on GFR and Albuminuria

• Albuminuria - presence of albumin in urine, problem with kidney filtration, from A1 to A3

• GFR from G3a to G5 progressive decrease in kidney function until kidney failure (G5), which requires dialysis (ESKD)

Cockroft and Gault formula

• Used for estimation of creatinine clearance and dosing medications

• Very accurate for pts with stable kidney function

• Tends to overestimate renal function in pts with moderate/sever kidney impairment

• Men: (140 - age)/IBW (Scr x 72)

• Women: CrCl x 0.85

Uremia

Build up of waste products in the blood

• Increase in Blood urea nitrogen, confusion, N/V, anorexia

• Kidney supposed to excrete nitrogenous wastes of metabolism from the blood

• Monitor BUN to asses signs/symptoms of Uremia

  • Uremic fetor (urine breath)

  • Uremic frost on skin (uric acid crystals)

Fluid Retention

Problem with water retention, edema and increase in blood pressure

• No need to fluid restrict IF Na+ lvls are controlled(look at diet)

• Diuretics(Won’t work in pts w/o functioning kidneys): volume overload and HTN in pts w/renal insufficiency or pts making some urine

  • Thiazides ineffective Crcl < 30ml/min, loops will work

  • Avoid Potassium sparing diuretics (Spironolactone, Eplerenone)

Ethacrynic Acid

Loop diuretic that contains no sulfa component, good for pts with sulfa allergies

Electrolyte imbalances - Na+

• No need to severely restrict beyond no salt added diet UNLESS needed for hypertension/edema. Less than 2g Na/day or less than 5g NaCl/day

  • Caution using saline IV solutions

  • Make pts aware of high Na content foods

Electrolyte imbalances - K+

• Restrict to 3gm/day, goal of ESRD pt is pre-dialysis K of 4.5 to 5.5 mEq/L

  • Avoid high potassium foods(tomatoes, salt substitutes

Mineral and Bone Disorder

Disorder where Progressive kidney disease leads to hyperphosphatemia, decreased active vitamin D(1.25 - dihydroxyvitamin D₃).

• This leads to increased PTH production mainly from hypocalcemia

• This leads to increased Renal calcium reabsorption, which the body starts to break down bones for (vertebrae first)

Phosphate binders

Drug class that is used to treat Hyperphosphatemia, binds to dietary phosphate ingested in food and the chelate is eliminated in the feces. B/c of this HAVE to be given with meals.

Calcium Carbonate (tums)

• The Cheapest Calcium containing phosphate binder, around 40% elemental calcium

• Don’t exceed 1500mg of elemental Ca/day, 500mg/ TID with meals

• Common side effect is Constipation

Calcium Acetate (PhosLo)

• around 25% elemental calcium

• Important to not exceed 1500mg of elemental Ca/day

• Binds twice as much phosphate compared to calcium carbonate when given at same elemental dose, may have fewer hypercalcemic events as well

Sevelamer Carbonate (Renvela)

• Non Calcium containing phosphate binder, Non Absorbable hydrogel which lowers risk of systemic toxicity

• Decreases Uric acid levels - Good for gout pts

• Decreases LDL lvls by 15-30%

• No risk of Hypercalcemia

Lanthanum Carbonate (fosrenol)

• Non Calcium containing phosphate binder, comes in chewable tablet form

• Can titrate up to 1500-3000 mg/day

• Does not cross the BBB, no long term accumulation

• Eliminated through the feces

Sucroferric Oxyhydroxide (Velphoro)

• Non-calcium containing phosphate binder

• 500 mg chewable tablet BID with meals, titrate by 1 tablet per day each week

• may cause darkened stools due to iron content, however, no effect on iron parameters

Auryxia (ferric citrate)

• Non-calcium containing phosphate binder, Mainly for CKD patients on dialysis

• 2 tablets TID per day with meals, 1g ferric citrate/tab

• Can cause discolored feces

• Increase both TSAT (Transferrin saturation, transport) as well as Ferritin (Stored iron) lvls

Aluminum Hydroxide (Amphojel)

• Cheap Non-calcium containing phosphate binder, used rarely

• Aluminum toxicity is a side effect (Al is removed by the kidneys)

• Should only be for short term use (less than 4 weeks)

Dietary restrictions - Phosphorous

• Should be restricted to 800-1000 mg/day

  • CKD stage 3 and 4 (Phos > 4.6mg/dL) or CKD stage 5

  • PTH > target range for stage 3,4, or 5

• Avoid foods high in phosphorous (Meats, nuts, beer, dairy, etc…)

Vitamin D and secondary hyperparathyroidism (SHPT)

• Hyperphosphatemia and kidney’s inability to activate Vitamin D leads to decrease in calcium. This leads to more PTH being produced to start taking calcium from the bones

Treatment of Secondary hyperparathyroidism (SHPT)

• Unactive Vitamin D (Ergocalciferol) and active Vitamin D sterols (Calcitriol, paricalcitol, doxercalciferol) increase Vitamin D concentrations, lowering PTH concentrations through negative feedback mechanism

• CKD stage 3, 4 pts can convert ergocalciferol to calcitriol, BUT stage 5 pts need the already active forms of Vitamin D due to not having enough kidney function left