Chronic Kidney Disease

Question 1

what are the three overarching functions of the kidney?

Answer 1

• excretory
• homeostatic
• hormonal

Question 2

excretory function

Answer 2

water
solutes
-electrolytes
-metabolic end products

Question 3

what is the basic filtering unit of the kidney?

Answer 3

nephron

Question 4

what is the first component of a nephron?

Answer 4

the glomerulus

Question 5

permeability or fractional clearances are dependent on?

Answer 5

size and charge. the smaller the molecule size, the more likely that it will get filtered (water, salts, metabolic wastes, small nutrients). The more negative a molecule the less permeable.

Question 6

example molecules

Answer 6

albumin: negatively charged and radius is 36
dextran: positively charged

Question 7

what are all of the components of the nephron?

Answer 7

glomerulus, convoluted tubules and collecting ducts

Question 8

what are the functions of the tubules?

Answer 8

secretion
-cations, anions and charged compounds
-important for acid secretion and maintenance of physiological concentrations of electrolytes, and drug elimination
reabsorption
-electrolytes, glucose, aminoacids, proteins, water, urea
-recover freely filtered substances

Question 9

what are the mechanisms of waste elimination?

Answer 9

urea (50%)
-free filtration
-passive reabsorption
creatinine (110-115%)
-free filtration
-active secretion
hippuric acid (~100%)
-poor filtration
-active secretion

Question 10

what is the glomerular filtration rate (GFR)?

Answer 10

• the rate at which plasma is filtered across the glomerulus (ml/min)
• determines excretory and homeostatic function
• normal: ~100ml/min (range: 90-150 ml/min)

Question 11

glomerular filtration rate can be associated with

Answer 11

• renal disease
• it is important to note that urine volume is not reflective of GFR bc tubular and secretion determines concentration of waste products

Question 12

GFR measurement

Answer 12

-substance filtered/day=substance excreted in urine/day
-[plasma substance level] x plasma fluid filtered/day=substance excreted in urine/day
GFR:
=[urine substance level] x volume/day / [plasma substance level] : UV/P

Question 13

what are the three formulas for GFR estimation?

Answer 13

cockcroft-gault formula: age, weight, sex and creatinine concentration
MDRD formula: creatinine concentration, age, race, sex (more reliable that cockcroft but less so at extremes of age)
CKD-EPI formula: creatinine concentration, age, race, sex

Question 14

GFR and Weight

Answer 14

creatinine
-synthesized by skeletal muscle
-muscular individuals with higher levels
-malnourished individuals with lower levels
BUN (blood urea nitrogen)
-byproduct of protein intake
-poor nutrition may lower the BUN level

Question 15

What is the relationship between GFR and age?

Answer 15

GFR declines with aging, and as a result of decreased muscle

Question 16

What is the relationship between the serum creatinine and GFR?

Answer 16

they are inversely related

Question 17

chronic kidney disease

Answer 17

• definition: progressive in GFR
• irreversible
• progression to end-stage renal failure (ESRD) requiring renal replacement therapy

Question 18

clinical manifestations

Answer 18

stage 1: GFR >90 Normal
stage 2: GFR 60-90 Early Renal Insufficiency
stage 3: GFR 30-60 Chronic Renal Failure
stage 4: GFR 15-30 Pre-End Stage Renal Disease
stage 5: GFR <15 End Stage Renal Disease

Question 19

Epidemiology

Answer 19

prevalence: ~500k
higher incidence among select racial groups
-african-americans
-native americans

Question 20

Etiology

Answer 20

most common causes:
-diabetes mellitus
-hypertensive nephrosclerosis
-chronic glomerulonephrotis
Other
-polycystic kidney disease (familial)
-glomerular/vascular/tubular/interstitial disease

Question 21

progressive renal disease

Answer 21

• irreversible damage of select glomeruli
• intact glomeruli hyperfiltrate
• high blood flow
• glomerular hypertension
• high pressure damage to remaining glomeruli
• increased permeability to protein –> proteinuria
• nephrosclerosis - scarring

Question 22

what is the homeostatic function?

Answer 22

volume regulation (tonicity)
-Na* handling
water balance 
acid handling
potassium handling

Question 23

clinical manifestations

Answer 23

• hypervolemia- excess volume
• (Na+ & H2O retention)
• hyponatremia (low Na+ concentration)
• excess water = hypo-osmolality
• hyperkalemia- excess potassium
• metabolic acidosis- excess acid
• anemia- low hemoglobin
• prolonged bleeding time
• renal bone disease
• uremia

Question 24

renal Na+ handling

Answer 24

net Na excretion: <1% (150 mEq/day)

Question 25

describe the clinical and physical findings of hypervolemia

Answer 25

``` decreased Na excretion - dec. GFR -> Na and H2O retention physical findings -hypertension (HBP) -shortness of breath due to pulmonary edema (fluid in the lungs) -peripheral edema (swelling of the legs) ```

Question 26

describe the clinical findings of hypertension

Answer 26

high pressure at the glomerulus -increases kidney damage increases protein in the urine (abnormal) greater cardiovascular morbidity and mortality

Question 27

Describe the aspects of renal water handling

Answer 27

``` filter: 140 L per day reabsorption: -70% proximal tubule -15% descending limb of loop of henle -collecting duct: antidiuretic hormone (8L - 19.5L) ```

Question 28

describe the clinical presentations of hyponatrmia

Answer 28

- poor H2O excretion due to compromised tubular function (poor urinary diluting function) - mostly in the setting of excess free water intake - confusion, seizures with severe derangements

Question 29

describe acid handling

Answer 29

- acid generated with protein rich diet, metabolic processes * protein -> sulfuric acid/phosphoric acid - daily "cid intake" ~ 60-120 mEq - kidneys regulate and eliminate H+ * buffering of H+ * excretion

Question 30

Proximal tube and distal tube are used for?

Answer 30

reabsorption of HCO3 and secretion of H

Question 31

normal levels of H+ are 40 nEq but acidemic states lead to

Answer 31

increase protein breakdown decrease cardiac (myocardial) function increase risk of arrythmias (abnormal heart rhythm) increase bone resorption (breakdown) impaired O2 uptake by hemoglobin (in red blood cells) in the lungs

Question 32

potassium homeostasis

Answer 32

k+ homeostasis important for normal cellular function -determines resting cell membrane potential -depolarization of muscle and neural cells normal K+ : -60mEq/Kg body weight -daily intake: ~50-150 mEq/day, normal plasma K 4 mEq/L -90% absorbed -immediately K is shifted from blood to inside cells until you can excrete into the urine

Question 33

renal potassium handling

Answer 33

``` filtration -glomerulus reabsorption (~100%) -proximal tubule -thick ascending loop of henle -almost no K reached distal tubule excretion** -active K+ secretion ```

Question 34

describe the clinical findings of hyperkalemia

Answer 34

decrease GFR and secretion leads to K+ retention and so cardiac arrest

Question 35

renal hormonal function

Answer 35

``` erythropoeitin vitamin D -stimulate Ca2+ *absorption from the gut -parathyroid hormone suppression *parathyroid hormone stimulation causes bone breakdown ```

Question 36

descibe the clinical presentations of anemia

Answer 36

- hormonal function - dec. erythropoeitin production - poor oral iron intake

Question 37

name the three possible treatments for anemia

Answer 37

transfusion erythropoeitin therapy iron replacement

Question 38

what is the function of vitamin D?

Answer 38

it is needed to absorb calcium from food

Question 39

renal osteodystrophy

Answer 39

poor bone formation due to: * hyperphosphatemia resulting in increased PTH - poor filtration of phosphorus * bone breakdown stimulated by PTH * impaired bone mineralization due to poor vitamin D activation -> low calcium * metabolic acidosis

Question 40

what is the treatment for renal osteodystrophy?

Answer 40

* phosphate binders * active vitamin D * parathyroidectomy in severe hyperparathyroididm

Question 41

Bleeding

Answer 41

platelet disorder: uremic toxins | anemia

Question 42

uremic symptoms

Answer 42

GI: nausea, vomiting, poor taste, decreased appetite Skin: itching CNS: fatigue, lethargy, depression, decreased intellectual and cognitive function, sleep disturbances Musculoskeletal: twitching, neuromuscular irritability, leg and arm craps Sexual dysfunction: decreased libido, amenorrhea Inflammatory symptoms of heart: pericarditis (inflammation of heart lining), pericardial effusion

Question 43

what is the treatment for uremia?

Answer 43

``` blood pressure control treatment of underlying disease -ex. diabetes mellitus lower protein in the urine -protein in urine is abnormal and indicates damage of the glomerulus ```

Question 44

how can one control complications of CKD?

Answer 44

restrict Na and water in diet/diuretics restrict K in diet avoid excess protein in diet but would not restrict it lower phosphate in diet with binders activated vitamin D to suppress PTH anemia: iron, erythropoietin, transfusion

Question 45

Hemodialysis and peritoneal dialysis

Answer 45

hemodialysis: a method that is used to achieve the extracorporeal removal of waste products such as creatinine and urea and free water from the blood when the kidneys are in a state of renal failure peritoneal dialysis: uses the patient's peritoneum in the abdomen as a membrane across which fluids and dissolved substances are exchanged from the blood.

Question 46

renal transplantation

Answer 46

* best long-term prognosis * long waitlist * ABO compatibility * lifelong immunosuppression * risk of infection