Course Case Studies

Pathophysiology: The Renal System

Course #38860 - $75 • 15 Hours/Credits

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    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.
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ACUTE GLOMERULONEPHRITIS

Patient A, a man 27 years of age, presents to an outpatient clinic complaining of two days of facial and hand swelling. He first noticed swelling around his eyes, along with difficulty putting on his wedding ring because of swollen fingers. Around the same time, he began to notice that his urine appeared reddish-brown. He reports having less urine output over the past several days. He has no significant medical history. His only medication is ibuprofen, which he took more than one week ago for fever and sore throat that have since resolved. On examination, he is afebrile, with a heart rate of 85 beats per minute and a blood pressure of 172/110 mm Hg. Patient A has periorbital edema; his funduscopic examination is normal, without arteriovenous nicking or papilledema. His chest is clear to auscultation. His heart rhythm is regular, with a nondisplaced point of maximal impulse, and he has no abdominal masses or bruits. The patient also has edema of his feet, hands, and face. A dipstick urinalysis in the clinic shows specific gravity of 1.025 with 3+ blood and 2+ protein, but is otherwise negative. A fresh-spun urine specimen is positive for red blood cell casts.

The physician diagnoses acute (likely poststreptococcal) glomerulonephritis. This condition is most likely to affect children with a history of upper respiratory infection or a history of strep throat one to three weeks earlier, although adults may also be affected. Patients present with edema, hypervolemia, hypertension, hematuria, and oliguria. Red blood cell casts on urinalysis verify the diagnosis. Systemic lupus erythematosus is another possible cause, but this patient has no signs or symptoms indicating this etiology.

Treatment of poststreptococcal glomerulonephritis focuses on managing hypertension and edema. Patient A is placed on a low-salt diet and liquid intake is restricted. If the edema was more severe, loop diuretics would be prescribed. However, the edema begins to resolve and his blood pressure begins to lower with conservative management. Additionally, Patient A is prescribed oral penicillin G at a dosage of 250 mg four times per day for 7 to 10 days to eradicate the nephritogenic strain. The patient is instructed to rest and avoid vigorous physical activity for a day or two.

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HEMATURIA

Patient B, a man 40 years of age with no past medical history, presents to the clinic to establish care. He reports that he had a prior urinalysis that revealed blood as an incidental finding. The urinalysis was done as a standard screening test by his former employer. He denies ever seeing any blood in his urine and denies any voiding difficulties, dysuria, sexual dysfunction, or any history or risk factors for sexually transmitted infections. His review of systems is otherwise negative. He reports having smoked a half-pack of cigarettes per day for the past 10 years and jogging 15 minutes and light weight training daily. On examination, his vital signs are normal, and the entire physical examination is unremarkable. A complete blood count and a chemistry panel (electrolytes, blood urea nitrogen, and creatinine) are normal. The results of a urinalysis are:

  • Specific gravity: 1.015

  • pH: 5.5

  • Leukocyte esterase: Negative

  • Nitrites: Negative

  • White blood cell count: 0

  • Red blood cell count: 4–5 per high-power field

The likely diagnosis is determined to be asymptomatic microscopic hematuria. Repeat urinalysis is ordered to assess for risk factors. A urine culture is necessary to rule out infection. Imaging studies are also ordered. The primary concern is to rule out malignancy, including renal cell carcinoma and transitional cell carcinoma. The nurse counsels Patient B on the importance of an appropriate work-up, but reassures him that the prevalence of renal cancers is low. Because the patient is a smoker, bladder cancer should be ruled out (or identified) as soon as possible.

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NEPHROTIC SYNDROME

Patient C, a Hispanic woman 48 years of age, presents to a medical office complaining of persistent swelling of her feet and ankles, to the degree that she cannot put on her shoes. She first noted mild ankle swelling approximately two to three months previously. She borrowed some diuretic pills from a friend, and the pills seemed to help, but now she has run out. She also reports that she has gained 20 pounds over the last few months, despite regular exercise and trying to adhere to a healthy diet. Her medical history is significant for type 2 diabetes, for which she takes a sulfonylurea agent. She neither sees a physician regularly nor monitors her blood glucose at home. She denies dysuria, urinary frequency, or urgency, but she does report that her urine has appeared foamy. She has had no fever, joint pain, skin rashes, or gastrointestinal symptoms.

Her physical examination is significant for mild periorbital edema, multiple hard exudates, and dot hemorrhages on funduscopic examination. She also has pitting edema of her hands, feet, and legs. Her heart rhythm is regular without murmurs, and her abdominal examination is benign. She has diminished sensation to light touch in her feet and legs to mid-calf. A urine dipstick performed in the office shows 2+ glucose, 3+ protein, and negative leukocyte esterase, nitrates, and blood.

The presumed diagnosis is nephrotic syndrome secondary to diabetic nephropathy. A 24-hour urine collection is taken to measure proteinuria and to verify the diagnosis. Usual causes in adults include diabetes, hepatitis B, amyloidosis, lupus erythematosus, and drugs such as penicillamine and captopril.

Maintenance of glycosylated hemoglobin (HbA1c) to 7.0% or lower is recommended, and Patient C is started on diabetes care (with regular follow-up and screening). To address the nephrotic syndrome, an ACE inhibitor is prescribed to control her blood pressure. In order to meet her blood pressure targets more quickly, a diuretic is also prescribed. Patient C is instructed to limit her intake of fluids and protein (to less than 2 g/day). She is asked to return in several weeks for additional screening and to call if the edema does not resolve.

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URINARY TRACT INFECTION-ASSOCIATED SEPSIS

The emergency resident calls up a new admission, describing a female patient, 84 years of age. Patient D was brought to the emergency department by ambulance from her long-term care facility for increased confusion, combativeness, and fever. Her medical history is significant for Alzheimer disease and well-controlled hypertension; otherwise, she has been healthy. The resident states that the patient is "confused" and combative with staff, which, per her family, is not her baseline mental status. Her temperature is 100° F, heart rate is 130 beats per minute, blood pressure 76/32 mm Hg, respiratory rate 24 breaths per minute, and oxygen saturation 95% on room air. On examination, Patient D is lethargic but agitated when disturbed. Her neck veins are flat, her lung fields are clear, and her heart rhythm is tachycardia but regular, with no murmur or gallops. Abdominal examination is unremarkable, and her extremities are warm and pink.

After administration of 2 L of normal saline over 30 minutes, her blood pressure is 95/58 mm Hg. The initial laboratory work indicates a white blood cell count of 14,000/mm3, with 67% neutrophils, 3% bands, and 24% lymphocytes. No other abnormalities are noted. Chest x-ray obtained in the emergency department is normal. Urinalysis of a catheterized sample shows 2+ leukocyte esterase, negatives nitrite, and trace blood. Microscopy shows 20–50 white blood cells per high-power field, 0 to 3 red blood cells, and many bacteria.

Patient D is diagnosed with urinary tract infection that has progressed to sepsis and possibly shock. She has several risk factors that predispose her to urinary tract infection, including older age, female sex, cognitive dysfunction, and fecal incontinence. Blood pressure support is continued, with IV fluids or vasopressors as necessary. Broad-spectrum antibiotics are started immediately. As the infection clears, the patient's combativeness resolves as well.

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ACUTE RENAL FAILURE

Patient E is a man, 42 years of age, who has driven to the mountains to hunt. While tramping through thick woods, a stray bullet (perhaps from another hunter) hits Patient E's thigh, tearing into muscles and blood vessels. He is thrown to the ground and temporarily loses consciousness. When he awakens a few minutes later, his leg is bleeding profusely. He yells for help, but there is no reply.

The patient slows the bleeding somewhat by tying his shirt around his leg and manages, with great effort, to get to a rural roadside where he again loses consciousness. A driver finds him a few hours later, pulls him into his car, and takes him to the hospital.

When he arrives, Patient E is immediately treated for shock that resulted from extensive blood loss. He is taken to surgery, and his leg is repaired. Although the patient's blood pressure increases and his pulse rate decreases with appropriate fluid replacement and cessation of blood loss, his urine output remains low.

Two days after admission, Patient E's total urine output has been 320 mL, with an average specific gravity of 1.013. His blood pressure is 150/95 mm Hg (an increase from his previous average of 125/80 mm Hg). His pulse is 90 beats per minute, and his respirations are 18 breaths per minute. He is complaining of nausea, which seems unrelated to the administration of his pain medication. Significant blood tests reveal a BUN of 48 mg/dL and elevations in serum creatinine and potassium. Urinalysis results are consistent with renal failure findings. A diagnosis of acute renal failure secondary to prolonged hypovolemic shock is made. Patient E's physicians administer trial doses of mannitol and furosemide (Lasix) in an effort to produce diuresis. Because no increase in urine results from this therapy, further diuretics are not employed. However, his physicians hope to manage him conservatively and avoid dialysis, if possible.

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POLYCYSTIC KIDNEY DISEASE

Patient F is a white woman, 35 years of age, with a history of frequent urinary tract infections who now presents with gross hematuria. On physical exam, she is thin with a palpably enlarged right kidney. On questioning, she states that her mother had some sort of "cyst disease" of the kidney. She further states that her mother died of a heart attack several years ago, at 62 years of age. A renal ultrasound reveals numerous large, fluid-filled cysts on the right kidney and several cysts on the left kidney. Further imaging also reveals a fluid-filled cyst visible on the liver. A consultation with nephrology and a geneticist results in a diagnosis of autosomal dominant polycystic kidney disease (ADPKD).

ADPKD is the fourth leading cause and the leading genetic cause of ESRD, and the most common life-threatening hereditary disease in the United States. ADPKD occurs in approximately one of every 1,000 live births. Children of affected individuals have a 50% chance of inheriting the disorder.

Patients with ADPKD can present with flank pain, hematuria, and/or palpable kidneys. Individuals with a family history are considered to have ADPKD if ultrasound reveals two unilateral or bilateral cysts in patients 15 to 30 years of age, two or more cysts in each kidney for patients 30 to 59 years of age, or four or more cysts in each kidney in patients older than 60 years of age. For patients with no known genetic risks (either from family history or genetic testing), the diagnostic criteria are three or more unilateral or bilateral cysts in patients 15 to 39 years of age or two or more cysts in each kidney for patients 30 to 59 years of age.

While the predominant clinical feature of ADPKD is renal disease (50% of affected patients have ESRD by 60 years of age), extrarenal manifestations are also common, which suggests that the disease may involve a generalized collagen disorder. As well as liver and pancreatic cysts, patients have an increased risk of cerebral hemorrhage due to intracranial aneurysms, cardiac valve abnormalities, aortic root dilation, and abdominal hernias.

  • Back to Course Home
  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.