renal disease

renal physiology

clears nitrogenous waste from breakdown of protein, regulates volume status, maintains electrolyte levels, eliminates some drugs, synthesizes and metabolizes some hormones

renal anatomy

each kidney has approximately 1 million nephrons

glomerulus: blood filters

proximal tubule: substances are actively/passively reabsorbed, secreted, or metabolized

loop of henle: fluid and electrolyte regulation

collecting duct: where urine is collected

GFR

noted as best overall value for determining kidney function

estimated clinically

usually creatinine is used to estimate GFR

creatinine

good estimation of creatinine breakdown in the muscle, excreted by the kidney

what is filtered by the kidney

electrolytes: sodium, potassium, chloride

minerals: calcium, phosphorous, mg, zn, selenium

gluocose, small protein, AA, vitamins

vitamin d activation

important for renal physiology

vit D activated in kidney through 1 alphahydroxylase

parathyroid hormone

activates more vitamin d and active form of vitamin D and it can lead to improved absorption of calcium and phosphorous and phosphorous excretion to rebalance

as parathyroid hormone increases

it leads to bone resorption and calcium release from the bones

erythropoietin EPO

hormone produced in the kidney, stimulates RBC production in the bone marrow

it is a stimulating agent given to pts on dialysis

what else is needed for pts on EPO

IV iron also necessary due to low levels of iron, make sure they have enough to make some

gng in kidney (most is in the liver but rarely)

in fed state it makes up 10% of the gng, in fasted state it takes up 40% of the gng especially prolonged

when GFR is reduced what happens to kidney gng

it is reduced, which leads to an impaired response to hypoglycemia

concern for those with diabetes

hypoglycemia

related to anorexia with decreased food intake, seen with CKD with ^ nitrogenous waste and decreased appetite, oral intake, shift in catabolic state.

hyperglycemia

diabetes often occur together, with insulin resistance in T2D

-the decrease in renal glucose excretion leads to it

-inflammation in CKD

-accumulation of counterbalance hormones that kidneys can’t get rid of

acute kidney injury

abrupt decline in kidney function over hours to days, reduced glomerular filtration and tubular function

what does acute kidney injury lead to

-hyperkalemia, hyperphosphatemia, glucose intolerance, fluid overload, acidosis, and azotemia

-30-80% mortality rate

pts with AKI

may be in catabolic state, releasing cell contents from breakdown of tissue, needs to be filtered by kidneys that are already strained

azotemia

accumulation of blood urea nitrogen and nitrogenous waste products

continuous renal replacement therapy CRRT

often used for AKI, slowly filters the blood while avoiding large volume shifts that are seen with hemodialysis (More unstable)

in pts with AKI

you will see rising serum creatinine and decreasing urine output

acute injury three causes

prerenal cause-before the kidney

intrinsic causes-within the kidny

post renal cause- after the kidney

prerenal causes

shock, myocardial infarction, severe dehydration, 50-60% AKI causes

intrinsic causes

toxic drugs, allergies, prolonged ischemia, ischemic acute tubular necrosis, glomerulenephritis, strep, 20-30% of causes

post renal

bladder cancer, benign prostatic hypertrophy, stricture or obstruction in ureters and or urethra

5-15% of causes

nutrition intervention AKI advice

preserve LBM, prevent or treat malnutrition, provide adequate calories and protein, prevent nutritional deficiencies and maintain balance

nutrition for AKI calories energy, etc

protein 0.8-1.2, energy 25-35 kcal/kg, sodium 2-3g, potassium 2-3g, phosphorous 8-15mg, fluid 500mg over urine output

dont supplement AKI

vitamin A

chronic kidney disease

abnormalities of kidney stricture or function that are present for at least 3 months

CKD progressive

rate varies at each stage, depends on BP, BG, comorbidities of HTN, diabetes influence progression

how long does kidney remain functioning

until more than 60% of the nephron fail

risk factors for CKD

diabetes, htn, autoimmune disease, systemic infections, UTIs, urinary stones, family history, drugs, low birth weight

demographic factors ckd

age, exposure to chemicals/environments, low income/education, ethnicity

stage 1 CKD

eGFR= 90-130mL/min

kidney damage, normal to increased kidney function

stage 2 ckd

eGFR 60-89

mild decrease in kidney function

stage 3 ckd

30-59 ml/min

moderate decrease in kidney function

stage 4 ckd

15-29 mL/min

severe decrease in kidney function

stage 5 ckd

less than 15 eGFR

kidney failure with treatment needed, end stage renal disease

treatment of ckd

hemodialysis, peritoneal dialysis

hemodialysis

maintains fluid and electrolyte balance and prevents accumulation of nitrogenous waste products and other waste products

blood pumps through filter with semipermeable membrane; dialysate sent in opposite direction, helps get rid of excess fluid

peritoneal dialysis

home therapy, less common

peritoneum acts like semipermeable membrane where solutes and water cross from blood to peritoneal fluid

dextrose based fluid

continuous vs cycling

kcal/kg rec for hemodialysis and CRRT

30-35 kcal/kg

protein for non dialysis kidney disease is low bc it will slow the progression, but some dialysis you need to ^ needs

zinc

low serum zn seen in pts with PD

improved taste after supplementation and appetitie

aluminum

this toxicity is seen in pts with CKD 4 or 5 with or without renal replacement therapy

erythropoietin

stimulates production of RBCs

converting to 1,25 dihydroxy D3 the active form

what stage of vitamin D metabolism occurs in the kidneys

generally unrestricted

potassium guidelines for a patient on peritoneal dialysis

protein needs predialysis

generally low because low protein slows the progression of CKD

protein needs dialysis

generally increase while on dialysis(to more normal levels) because the dialysate recycles protein

loop of henle

functional unit of the nephron that is responsible for water/sodium balance