Nephrology
12.1 Acute Renal Failure
Cause:
Pre-renal: Hypovolemia, anemia.
Renal: Drug toxicity [eg, NSAIDs (Am J Epidem 2000;151:488)—even topical (BMJ 2000;320:93)] and salicylates and acetaminophen possibly implicated in chronic renal failure (CRF) (Nejm 2001;345:1801); acute tubular necrosis (ATN)—as seen in shock, crush injuries, hypothermia, heavy metal toxicity, snake venom toxicity, organic solvent toxicity, intravascular hemolysis; rhabdomyolysis from drug abuse, such as ethanol, iv heroin, and more recently iv temazepam (Qjm 2000;93:29) or wild mushroom intoxication (Nejm 2001;345:798); iv dye reaction in those with underlying renal insufficiency; multiple myeloma (Nephron 2000;85:96); HIV with many etiologies such as interstitial nephritis (Am J Kidney Dis 2000;35:557).
Post-renal: Obstruction.
Epidem: Community-acquired is much more common (3×) in the black population compared to whites (Arch IM 2000;160:1309), with possibly higher mortality rates.
Pathophys: Many physiologic effects from cellular death and ATP depletion, many competing theories of most significant mechanism (Semin Nephrol 2000;20:4). Ensuing acidosis, calcium
phosphorus imbalances, hyperkalemia, anemia, HT, peripheral and autonomic neuropathy from PTH; delayed hypersensitivity immune suppression, pruritus probably from histamine.
phosphorus imbalances, hyperkalemia, anemia, HT, peripheral and autonomic neuropathy from PTH; delayed hypersensitivity immune suppression, pruritus probably from histamine.
Uremia may lead to sallow skin, pericardial effusion.
Sx: Lassitude, pruritus, nausea/vomiting, anorexia, muscle cramps, sleep disturbance.
Si: Uremic breath, increased pigmentation, postural hypotension or hypertension, absent tendon reflexes and other peripheral neuropathies—reversible.
Crs: Variable, even straightforward causes (eg, hypovolemia) may progress to a chronic process; poorer prognosis with increased age, recent MI, CHF, requiring respiratory support, or liver dysfunction (Clin Nephrol 2000;53:10).
Cmplc: Chronic renal failure; secondary infection (Nephrol Dial Transplant 2000;15:212).
Lab: CBC with diff; metabolic profile including calcium, magnesium, phosphorus; UA; urine culture; venous pH/ABG; type and screen; EKG. Screening for renal dysfunction before iv contrast with serum creatinine has been advocated, and may even consider urine dipstick for protein as a screen (Emerg Radiol 2004:319)—obviously, risk benefit decision on the utility of the study vs time for screening of renal dysfunction must be weighed.
X-ray: Renal US.
Calculating Creatinine Clearance (CrCl or CCr) (Nephron 1976;16:31):
CrCl = [(140 − age) × weight (kg)/ (72 × serum creatinine)] × (0.85 for women)
Emergency Management:
Hold all potentially offending drugs; place indwelling catheter.
Consider iv fluid bolus for hypovolemia (Drugs 2000;59:79), correction of anemia.
Trial of α-blocker Alfuzosin 10 mg/d for 3 d with catheter removal after two doses and one additional dose after catheter removal with an odds ratio for success almost 2, with failures seen with older age (> 65 yr of age) and higher initial retention volumes (> 1000 ml)—this was studied in those with BPH (J Urol 2004;171:2316).
Treat underlying arrhythmias/hyperkalemia, as warranted.
Thyroxine of no help in euthyroid patients (Kidney Int 2000;57:293).
Dialysis to prevent complications and death (Kidney Int 1972;1:190), better with daily treatment (Nejm 2002;346:305).
Prevention:
Hydration with 154 mEq/L of sodium bicarbonate with a 3 cc/kg bolus 1 hr before the procedure and follow this with 1 cc/kg per hr for 6 hr after the procedure to decrease the incidence of contrast-induced nephropathy from 13.6% to 1.7% when comparing against NS (same volumes) (Jama 2004;291:2328)—whether this translates into treatment of actual clinical disease is debatable.
Acetylcysteine 600 mg po bid × 2 d prior to procedure with iv dye in those with moderate CRF (Jama 2003;289:553)—same caveat as to whether this prevents actual clinical disease.
Perhaps use iso-osmolar dimeric, nonionic contrast (iodixanol) in those who need iv dye (Nejm 2003;348:491).
12.2 Dialysis Patient Issues
Cause: Patients receiving either peritoneal dialysis or hemodialysis have a time intensive commitment, but those with hemodialysis have less flexibility and more side effects.
Pathophys: Continuous ambulatory peritoneal dialysis (CAPD) with similar biochemical results as hemodialysis (HD) (Arch IM 1986;146:1138).
Adverse Effects: Similar in the two types of dialysis patients:
Folate deficiency (BMJ 1969;2:18)
EKG artifacts from fistula/cannula arm
Pericarditis (Am J Med 1977;63:874)
Pneumonia, atelectasis, and pleural effusion from CAPD (Lancet 1966;2:75)
Mortality = 10-20% per yr, 5% per yr from peritonitis in those with CAPD (Perit Dial Int 1997;17:S15)
Zinc deficiency (Am J Clin Pathol 1971;56:17) causes primary gonadal impairment, reversible with 2.5 mg po qd.
Amyloidosis (Kidney Int suppl 1993;41:S78)
Rare antacid Magnesium intoxication
Rare Cu intoxication from tubing (Nejm 1967;276:1209)
Iron deficiency
Increased ASHD (Lancet 1980;1:276)
Gynecomastia (Plast Reconstr Surg 1982;69:41)
Hepatitis C (Nephron 1993;65:40)
CaPO4 deposits in joints (Contrib Nephrol 1984;84:58).
Catheter displacement in those with CAPD (Clin Nephrol 1999;52:124).
Secondary hyperparathyroidism with change in bony structure (Kidney Int suppl 1993;41:S116).
Bleeding complications, secondary to platelet dysfunction and perhaps exacerbated by heparin use in those with hemodialysis (J Am Soc Nephrol 1991;2:961).
Infection at central catheter or shunt site in hemodialysis; tunnel infection and peritonitis in peritoneal dialysis (Arch Surg 1984;119:1325).
Scrotal swelling if patent processus vaginalis in those receiving peritoneal dialysis (Brit J Surg 1984;71:477)
Pure red cell aplasia with recombinant erythropoietin (Nejm 2002;346:469).Related posts:
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