CKD

Causes:

• • DM: diffuse glomerulosclerosis, nodular glomerulosclerosis (Kimmelstiel-Wilson lesions)

  • Idiopathic failure

  • HTN nephrosclerosis

  • Chronic GN

  • Chronic tubulointerstitial diseases

  • Polycystic kidney disease

Renal function in Chronic renal failure:

• • Usually Asx until GFR <50% of baseline.

  • Water and sodium balance: Decreased urine concentrating ability, easy dehydration, sodium wasting - initially. Later, there is volume overload after the kidneys are unable to excrete dietary sodium.

  • Potassium: When GFR is markedly lowered, K excreting capacity is lost.

  • Acid-Base balance: When GFR <50% of baseline the tubular excretion of H+ is impaired because renal production of ammonia is impaired, causing anion gap metabolic acidosis.

  • Calcium and phosphate:

  • Hypocalcemia, hyperphosphatemia

  • Decreased activation of vitamin D due to loss of 1-hydroxylase activity

  • 2° hyperparathyroidism

  • Severe bone resorption

  • Ectopic calcifications

  • Serum creatinine increases

  • BUN increases, but to a lesser extent than the creatinine

Si and Sx:

• • Uremic synd, nephrotic synd

  • US reveals shrunken kidneys with cortical thinning. Large kidneys seen in DM, HIV, PKD, amyloidosis, lymphoma.

Treatment:

At initial Dx, a 24-h creatinine clearance should be obtained; from then on Cr is followed for GFR.

Treat reversible causes

Diet: modest protein restriction with near normal caloric intake decreases nitrogen intake and avoids catabolism.

Fluids and electrolytes:

Sodium: restrict, but sodium and water depletion should be avoided

Phosphate: Prevent hyperphosphatemia. Minimize dietary phosphate (dairy products)

Dialysis.

CKD stages

• • Stage I: Kidney damage with normal or increased GFR - 90 or more ml/min/1.73 m2

  • Stage II: Kidney damage with mild decrease in GFR - 60 - 89

  • Stage III: GFR of 30 - 59

  • Stage IV: GFR of 15 - 29

  • Stage V: Kidney failure <15 (or dialysis)

The NKF K/DOQI has published guidelines for the evaluation, classification and stratification of chronic kidney disease. These guidelines define chronic kidney disease as:

1. Kidney damage for > 3 months, as defined by structural or functional abnormalities of the kidney, with or without decreased GFR, manifest by either:

a. pathologic abnormalities or

b. markers of kidney damage, including abnormalities in the composition of the blood or urine, or abnormalities in imaging tests

2. GFR < 60 mL/min/1.73 m2 for ? 3 months, with or without kidney damage.

ESRD is defined as a permanent loss of renal function that requires RRT; GFR <10 cc/min.