Uremia

Background

1. Uremia = clinical syndrome a/w end-stage renal disease (contamination of blood w/ urine)
   1. Correlation exists between uremia symptoms and low GFR (15-20% of nl)
   2. BUN/Cr are inaccurate markers of clinical syndrome of uremia
2. Contributing Factors:
   1. Excretory failure
      1. Leads to toxin accumulation
   2. Biosynthetic failure
      1. Loss of Vitamin D and erythropoietin
   3. Regulatory failure
      1. Uremic state produces excess free radicals -> atherosclerosis, amyloidosis

Clinical Features

Neurologic

1. 1. Uremic encephalopathy
      1. Diagnosis of exclusion
      2. Cognitive defects, memory loss, decreased attentiveness, slurred speech
      3. Asterixis, seizure, coma
      4. Improves w/ dialysis
   2. Dialysis dementia
      1. Similar to uremic encephalopathy except progressive, no improvement w/ dialysis
      2. EEG findings can differentiate uremic encephalopathy from dialysis dementia
   3. CVA
      1. Cerebrovascular disease, trauma, bleeding dyscrasias, anticoagulant, HTN
   4. Subdural hematoma
      1. 10x more likely than in general population
      2. Headache, focal neurologic deficits, seizure, coma
   5. Peripheral neuropathy
      1. Occurs in 60-100% of dialysis pts
      2. Paresthesias, impaired proprioception, weakness
      3. Autonomic neuropathy (postural dizziness, gastroparesis, bowel dysfunction)

Cardiovascular

1. CK-MB and troponin are specific markers of MI even in pts undergoing regular dialysis
2. Mortality from CV disease is 10-30x higher in dialysis pts than general population
3. HTN is common
4. Uremic cardiomyopathy
   1. Diagnosis of exclusion
   2. Circulating digitalis-like substances have been implicated
   3. Dialysis rarely improves LV function
5. Pericarditis
   1. Uremic pericarditis (75% of cases)
      1. Most common when the other symptoms of uremia are most severe
      2. BUN is nearly always >60
      3. Loud friction rub that is often palpable
      4. Typical pericarditis ECG changes are absent (inflammation does not involve myocardium)
         1. If ECG does have typical changes consider infection
   2. Dialysis-related (25% of cases)
      1. Most common during increased catabolism (trauma, sepsis) or missed dialysis sessions
      2. Constitutional symptoms, such as fever, are more common than in uremic pericarditis
   3. Treatment
      1. Dialysis
6. Tamponade
   1. Presents w/ AMS, hypotension, dyspnea
      1. Rarely present w/ classic signs of Beck's triad
   2. Pericardiocentesis should only be attempted if hemodynamically unstable
7. Pulmonary Edema
   1. Commonly ascribed to fluid overload; also consider MI
      1. Treat similar to non-ESRD pt
         1. Lasix 80mg IV may be effective even if minimal Urine output (pulmonary vasodilation)
      2. Preload reduction can be accomplished via:
         1. Induced diarrhea (sorbitol)
         2. Phlebotomy - withdrawal of as little as 150 mL is safe and effective
8. CHF
   1. May be preexisting
   2. May be caused by uremic cardiomyopathy, fluid overload, AV-related high-output failure

Hematologic

1. Anemia
   1. Without tx the hematocrit in ESRD pts should stabilize at 15-20%
   2. Treatment = erythropoietin
2. Bleeding diathesis
   1. Increased risk for all forms of bleeding (GI, ICH, liver hematoma)
   2. Treatment = desmopressin, cryoprecipitate, conjugated estrogen
3. Immunodeficiency

GI

1. 1. Anorexia, N/V
   2. Increased incidence of GI bleeding, diverticular disease, ascites

Renal bone disease

1. 1. Metastatic calcification (calciphylaxis)
      1. When calcium-phosphate product (Ca x PO4) > 70-80, metastatic calcification can ensue
      2. Symptoms of pseudogout, skin/finger necrosis (small vessel involvement)
      3. Life-threatening calcifications can occur in the cardiac and pulmonary systems
      4. Tx = use of low-calcium dialysate and phosphate-binding gels
2. Hyperparathyroidism (osteitis fibrosa cystica)
   1. Calciphylaxis + vitamin D3 deficiency results in depressed Ca, stimulation of PTH
      1. Leads to high bone turnover > weakened bones > increased fracture susceptibility
   2. Tx = phosphate binding gels, vitamin D3 replacement
3. Vitamin D3 deficiency and aluminum intoxication (osteomalacia)
   1. Leads to osteomalacia (defect in bone calcification)
   2. Symptoms similar to hyperparathyroidism (muscle weakness, bone pain)
   3. Tx = desferrioxamine
4. Amyloidosis
   1. Common in pts >50yr who have received dialysis for >10yr
   2. Complications: GI perforation, bone cysts w/ pathologic fx, arthropathies

Source

Tintinalli