Internal Medicine - Renal

Front 1

Acute Renal Failure
Diagnosis

Back 1

1. Blood tests
- Elevation in BUN and Cr levels
- Electrolytes (K, Ca, PO), albumin levels, CBC with differential
2. Urinalysis
- Dipstick test + for protein (3+, 4+) suggests intrinsic renal failure due to glomerular insult
- Microscopic examination of urine sediment
- Hyaline casts (prerenal failure)
- RBC casts (glomerular disease)
- WBC casts (renal parenchymal inflammation)
- Fatty casts (nephrotic syndrome)
3. Urine chemistry
- Urine Na, Cr, osmolality
- FENa: < 1% (prerenal failure); >2%-3% (ATN)
- Renal failure index: <1% (prerenal); >1% (ATN)
4. Urine culture (if infection is suspected)
5. Renal ultrasound
- Evaluate kidney size, excluding urinary tract obstruction (postrenal failure)
6. CT scan (abdomen and pelvis)
7. Renal biopsy: suspicion of acute GN or acute allergic interstitial nephritis
8. Renal arteriography: evaluate for renal artery occlusion

Front 2

Acute Renal Failure
Treatment

Back 2

1. General measures
- Avoid meds that decrease renal blood flow (NSAIDs) and/or that are nephrotoxic (aminoglycosides, radiocontrast)
- Adjust medication dosages for level of renal function
- Correct fluid imbalance
- Correct electrolyte disturbances
- Optimize cardiac output (BP should be 120-140/80-90
- Order dialysis if symptomatic uremia, intractable acidemia, hyperkalemia, or volume overload develop
2. Prerenal
- Treat underlying disorder
- Give normal saline to maintain euvolemia and restore blood pressure (but not to patients with edema or ascites). May need to stop anti-hypertensive meds
- Eliminate any offending agents (ACE-I, NSAIDs)
3. Intrinsic
- Once ATN develops, therapy is supportive. Eliminate the cause.
- If the patient is oliguric, furosemide may help to increase urine flow.
4. Postrenal - a bladder catheter may be inserted to decompress the urinary tract. Consider urology consultation.

Front 3

Chronic Renal Failure
Diagnosis

Back 3

1. Urinalysis - examine sediment
2. Measure Cr clearance to estimate GFR
3. CBC (anemia, thrombocytopenia)
4. Serum electrolytes (K, Ca, PO, serum protein)
5. Renal ultrasound
- Small kidneys are suggestive of chronic renal insufficiency
- Presence of normal-sized or large kidneys does not exclude CRF.
- Renal biopsy - to determine specific etiology

Front 4

Chronic Renal Failure
Treatment

Back 4

1. Diet
- Low protein: 0.7-0.8 g/kg
- Low-salt diet if HTN, CHF, or oliguria are present
- Restrict potassium, phosphate, and magnesium intake
2. ACE inhibitors: dilate efferent arteriole of glomerulus
- Reduce risk of progression to ESRD, slow progression of proteinuria
- Use with caution because they can cause hyperkalemia
3. BP control
- Strict control decreases rate of disease progression
- ACE inhibitors are preferred
4. Glycemic control (for diabetic patients)
5. Correction of electrolyte abnormalities
- Correct hyperphosphatemia with calcium citrate (phosphate binder)
- Prevent secondary hyperparathyroidism and uremic osteodystrophy with long-term oral calcium and Vit. D
- Acidosis: Oral bicarbonate replacement
6. Anemia: Treat with EPO
7. Pulmonary edema: Dialysis if condition is unresponsive to diuresis
8. Pruritis: Capsaicin cream or cholestyramine and UV light
9. Dialysis
10. Transplantation (the only cure)

Front 5

Dialysis
Absolute Indications

Back 5

Acidosis: Significant, intractable metabolic acidosis
Electrolytes: Sever, persistent hyperkalemia
Intoxications: Methanol, ethylene glycol, lithium, aspirin
Overload: Hypervolemia not managed by other means
Uremia (severe): based on clinical presentation, not lab values

Front 6

Hematuria

Back 6

Diagnosis:
1. Urine dipstick: sensitivity >90%
2. Urinalysis: crucial in evaluation
- Examine urine sediment for etiology
- If RBC casts and proteinuria are also present, a glomerular cause is almost always present (i.e. GN)
- If pyuria is present, send for urine culture
- If dipstick is positive for blood, but urinalysis is negative for microscopic hematuria (no RBCs), hemoglobinuria or myoglobinuria is likely present
3. Urine specimen: for cytology
- To detect cancers (bladder cancer)
- If suspicion is high, perform cystoscopy
4. 24-hour urine: Test for Cr and protein to assess renal function
5. Blood tests: coagulation studies, CBC, BUN/Cr
6. IVP, CT scan, ultrasound: if no cause is identified by the above tests; look for stones, tumors, cysts, ureteral strictures, or vascular malformations
7. Renal biopsy: if suspected glomerular disease

Treatment:
Treat underlying cause
Maintain urine volume

Front 7

Acute Interstitial Nephritis

Back 7

Diagnosis:
1. Renal function tests (increased BUN and Cr)
2. Urinalysis
- Eosinophils in the urine
- Mild proteinuria or microscopic hematuria may be present
3. Renal biopsy is the only way to distinguish between AIN and ATN
4. History of recent infection, start of new medication, rash, fever, general aches/pains may suggest diagnosis of AIN

Treatment:
1. Removing the offending agent is usually enough to reverse clinical findings
2. Treat infection if present.