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Flashcards in Nephrology Deck (27)
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1
Q

What are the symptoms and signs of acute renal failure?

A

Symptoms: Fatigue, nausea and vomiting, anorexia, shortness of breath, mental status changes. Signs: Increased levels of blood urea nitrogen (BUN) and creatinine, metabolic acidosis, hyperkalemia, tachypnea (caused by acidosis and hypervolemia), and hypervolemia (bilateral rales on lung examination, elevated jugular venous pressure, dilutional hyponatremia).

2
Q

What are the three broad categories of renal failure?

A

Prerenal, renal/intrarenal, and postrenal.

3
Q

Define prerenal failure. What are the causes? How do you recognize it?

A

In prerenal failure, the kidney is not adequately perfused. The most common cause is hypovolemia (dehydration, hemorrhage). Look for a BUN-to-creatinine ratio greater than 20 and signs of hypovolemia (e.g., tachycardia, weak pulse, depressed fontanelle). Give intravenous fluids and/or blood. Other com- mon prerenal causes are sepsis (treat the sepsis and give intravenous fluids), heart failure (give digoxin and diuretics), liver failure (hepatorenal syndrome; treat supportively), and renal artery stenosis (RAS).

4
Q

Define postrenal failure. What causes it?

A

In postrenal failure, urine is blocked from being excreted at some point beyond the kidneys (ureters, prostate, urethra). The most common cause is benign prostatic hypertrophy (BPH). Patients are men older than age 50 with BPH symptoms (e.g., hesitancy, dribbling); ultrasound demonstrates bilateral hydronephrosis. Treat with catheterization (suprapubic, if necessary) to relieve the obstruction and prevent further renal damage. Then consider surgery (transurethral resection of the prostate). Other causes are nephrolithiasis (but remember that stones generally have to be bilateral to cause renal failure), retroperitoneal fibrosis (watch for a history of methysergide, bromocriptine, methyldopa, or hydralazine use), and pelvic malignancies.

5
Q

What is the most common cause of intrarenal failure?

A

Intrarenal failure, which results from a problem within the kidney itself, is most commonly caused by acute tubular necrosis from various causes.

6
Q

What do you need to know about intravenous contrast and renal failure?

A

Intravenous contrast can precipitate renal failure, usually in diabetic patients and patients with preex- isting renal disease. Avoid contrast in such patients if possible. If you must give intravenous contrast, give lots of intravenous hydration before and after the contrast is given to decrease the chance of renal failure. Also consider the use of oral acetylcysteine on the day before and the day of contrast administration.

7
Q

True or false: Muscle breakdown can cause renal failure.

A

True. Myoglobinuria or rhabdomyolysis caused by strenuous exercise (e.g., marathon runners), alcohol, burns, muscle trauma, muscle compression (e.g., prolonged immobilization after a fall), heat stroke, and neuroleptic malignant syndrome may cause renal failure. The cellular debris that results from muscle breakdown plugs the renal filtration system. Look for very high levels of creatine phosphokinase (CPK). Treat with hydration and diuretics.

8
Q

What medications commonly cause renal insufficiency or failure?

A

NSAIDs; may cause acute tubular necrosis or papillary necrosis), cyclosporine, aminoglycosides, and methicillin.

9
Q

Define Goodpasture syndrome. How does it present?

A

Goodpasture syndrome is caused by the presence of measurable antiglomerular basement mem- brane antibodies, which cause a linear immunofluorescence pattern on renal biopsy. These antibodies react with and damage both kidneys and lungs. Look for a young man with hemoptysis, dyspnea, and renal failure. Treat with steroids and cyclophosphamide.

10
Q

Define Wegener granulomatosis. How does it present?

A

Wegener granulomatosis is a vasculitis that also affects the lungs and kidneys. Look for nasal involvement (bloody nose, nasal perforation) or hemoptysis and pleurisy as presenting symptoms, along with renal disease. Patients test positive for titers of antineutrophil cytoplasmic antibody (ANCA). Treat with cyclophosphamide and glucocorticoids. Methotrexate is an alternative.

11
Q

What is the prototypical cause of glomerulonephritis? How does it present?

A

Poststreptococcal glomerulonephritis is the classic example on board examinations. It usually affects children with a history of upper respiratory infection or strep throat 1 to 3 weeks earlier. Presenting symp- toms include edema, hypervolemia, hypertension, hematuria, and oliguria. Red blood cell (RBC) casts on UA clinch the diagnosis. Treat supportively. Also watch for lupus erythematosus as a cause of glomerulonephritis. Renal failure is a major cause of morbidity and mortality in patients with lupus.

12
Q

What are the indications for dialysis in patients with renal failure?

A

Whenever renal failure is present, first try to determine the cause and fix it, if possible, to correct the renal failure. Indications for acute dialysis include uremic encephalopathy, pericarditis, severe meta- bolic acidosis (roughly pH

13
Q

Define nephrotic syndrome. What causes it? How is it diagnosed?

A

Nephrotic syndrome is defined by proteinuria (>3.5 g/day), hypoalbuminemia, edema (the classic pattern is morning periorbital edema), and hyperlipidemia with lipiduria. In children it is usually caused by minimal change disease (podocytes with missing ”feet” on electron microscopy), which often follows an infection. Measure 24-hour urine protein or spot urine protein-to-creatinine ratio to clinch the diagnosis. Treat with steroids. Causes in adults include diabetes, hepatitis B, amyloidosis, lupus erythematosus, and drugs (e.g., gold, penicillamine, captopril).

14
Q

Define nephritic syndrome. What is the classic cause? How is it treated?

A

Nephritic syndrome generally is defined as oliguria, azotemia (rising BUN/creatinine), hypertension, and hematuria. The patient may have some degree of proteinuria, but not in the nephrotic range. The classic cause is poststreptococcal glomerulonephritis. Treatment is supportive, including control of hypertension and maintenance of urine output with intravenous fluids and diuretics.

15
Q

What causes chronic kidney disease (CKD)?

A

Any of the causes of acute renal failure can cause chronic renal failure if the insult is severe or prolonged. Most cases of CKD are a result of diabetes mellitus (number one cause) or hypertension (number two cause). A popular Step 2 cause is polycystic kidney disease. Watch for multiple cysts in the kidney and a positive family history (usually autosomal dominant; autosomal recessive form presents in children), hypertension, hematuria, palpable renal masses, berry aneurysms in the circle of Willis, and cysts in liver (Fig. 22-1).

16
Q

What metabolic derangements are seen in CKD?

A
17
Q

How is CKD treated?

A

Treat CKD with regular hemodialysis (usually 3 times/week), water-soluble vitamins (which are removed during dialysis), phosphate restriction and binders (calcium carbonate, calcium acetate, or sevelamer), erythropoietin as needed, and hypertension control. The only cure is renal transplant.

18
Q

What are the signs and symptoms of urinary tract infection (UTI)? What are the most likely organisms?

A

Symptoms and signs include urgency, dysuria, suprapubic and/or low back pain, and low grade fever. UTIs usually are caused by Escherichia coli (75% to 85% of cases) but may also be caused by Staphylococcus saprophyticus or Proteus, Pseudomonas, Klebsiella, Enterobacter, and/or Enterococ- cus species (or other enteric organisms). Patients who acquire UTIs in the hospital or from a chronic, indwelling Foley catheter are more likely to have organisms other than E. coli.

19
Q

What factors increase the likelihood of UTIs?

A

Female gender and conditions that promote urinary stasis (BPH, pregnancy, stones, neurogenic blad- der, vesicoureteral reflux) or bacterial colonization (indwelling catheter, fecal incontinence, surgical instrumentation) predispose to UTI.

20
Q

How do you diagnose and treat UTIs?

A

The gold standard for diagnosis is a positive urine culture with at least 100,000 colony-forming units (measure of bacterial load) of specific bacteria. At the least, get a midstream sample; the best method is a catheterized sample or suprapubic tap. Urinalysis shows white blood cells, bacteria (on Gram stain of the urine), positive leukocyte esterase, and/or positive nitrite. Empirical treatment usually is based on symptoms and urinalysis while awaiting culture results. Commonly used antibiotics include trimethoprim-sulfamethoxazole, amoxicillin, nitrofurantoin, cipro- floxacin, or a first-generation cephalosporin for about 5 days.

21
Q

Why are UTIs in children of special concern?

A

In children, a UTI is cause for concern because it may be the presenting symptom of a genitourinary malformation. The most common examples are vesicoureteral reflux and posterior urethral valves. Urine culture should be obtained. Order an ultrasound and either a voiding cystourethrogram or radionuclide cystogram to evaluate the urinary tract in any child 2 months to 2 years old with a first UTI. Recommendations for imaging in older children are less clear-cut.

22
Q

True or false: You should treat asymptomatic bacteriuria in most patients.

A

False. The exception is the pregnant patient, in whom asymptomatic bacteriuria is treated because of the high risk of progression to pyelonephritis. Use antibiotics that are safe in pregnancy, such as penicillins.

23
Q

How does pyelonephritis usually occur? What are the signs and symptoms? How is it treated?

A

Pyelonephritis most often is a result of an ascending UTI caused by E. coli (>80% of cases). Present- ing symptoms include high fever, shaking chills, costovertebral angle tenderness, flank pain, and/or UTI symptoms. Order urinalysis and urine and blood cultures to establish the diagnosis, but treat this life-threatening infection on an inpatient basis with intravenous antibiotics while awaiting results. A typical regimen consists of an oral fluoroquinolone or intravenous ceftriaxone or fluoroquinolone in uncomplicated pyelonephritis. Always choose an antibiotic regimen with good E. coli coverage.

24
Q

How do you differentiate among HUS, HSP, TTP, and ITP in terms of: age at presentation previous infection? RBC count Platelet count Peripheral smaer Effects on kidney Treatment Other signs and symptoms

A

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25
Q

Which is more likely to be seen on a plain abdominal radiograph: kidney stones or gallbladder stones?

A

Kidney stones (85%), which more commonly calcify (Fig. 22-3), are more likely to be seen than gallstones (15%).

26
Q

What are the signs and symptoms of renal stones? How are they diagnosed and treated?

A

Kidney stones (nephrolithiasis) generally present with severe, intermittent, unilateral flank and/or groin pain when the stone dislodges and gets stuck in the ureter (ureterolithiasis). Most stones can be seen on abdom- inal radiographs and are composed of calcium. Renal ultrasound or computed tomography (CT) scan can be used to detect a stone if clinical suspicion is high but plain abdominal radiographs are negative. Symptom- atic urolithiasis should be treated with lots of hydration and pain control (to see if the stone will pass). If the stone does not pass, it needs to be removed surgically (preferably endoscopically) or by lithotripsy.

27
Q

What causes kidney stones?

A

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