Renal Flashcards
This man has edema, hematuria, azotemia, hypertension, and oliguria, which are all features of ______ syndrome. It is a condition caused by glomerular inflammation (e.g., from post-streptococcal glomerulonephritis or rapidly progressive glomerulonephritis). This inflammatory process releases cytokines and results in damaged, porous glomerular capillaries.
nephritic
Microscopic hematuria (>3 RBC) and pyuria (>5 WBC) with hypertension and mild proteinuria (< 3+ on dipstick test) indicate nephritic syndrome. The acute onset of hemoptysis, dyspnea, and pulmonary infiltrates in a patient with nephritic syndrome indicates pulmonary-renal syndrome. The absence of features of systemic vasculitis (e.g., purpura, livedo reticularis) suggests a diagnosis of Goodpasture syndrome. Further evaluation is most likely to show increased serum titers of which of the following?
Goodpasture syndrome is caused by autoantibodies against the noncollagenous domain of the α-3 subunit in type IV collagen. The autoantibodies in Goodpasture syndrome specifically damage the glomerular basement membrane (anti-GBM antibodies) and the alveolar basement membrane, causing nephritic syndrome and alveolar hemorrhage without ever resulting in systemic vasculitis. IgG shows in inmunofluorescence.
A 42-year-old woman comes to the physician because of right flank pain that started 3 days following a procedure. Her vital signs are within normal limits. Physical examination shows right costovertebral angle tenderness. An intravenous pyelogram shows a dilated renal pelvis and ureter on the right with a lack of contrast in the lower third of the ureter. This patient most likely recently underwent which of the following procedures?
The lower third of the ureter (pelvic ureter) lies just below the cardinal ligament, which contains the uterine artery. Because the uterine arteries are ligated during a hysterectomy, the ureters are at risk of being injured. The ureters are also susceptible to injury during ovarian surgeries (e.g., oophorectomy) as they lie below the infundibulopelvic ligament, which contains the ovarian arteries.
A 68-year-old woman comes to the emergency department because of abdominal pain for 3 days. Physical examination shows guarding and tenderness to palpation over the left lower abdomen. Test of the stool for occult blood is positive.
This patient’s CT scan shows a horseshoe kidney. Her abdominal symptoms are likely unrelated to the renal pathology as a horseshoe kidney is often an incidental finding.
Which of the following mechanisms best explains the patient’s imaging findings?
Impaired organ ascent explains the presence of this horseshoe kidney at an inferior position relative to normal kidneys. The fused inferior poles of the horseshoe kidneys get caught under the inferior mesenteric artery, impeding the normal ascension of the kidneys to their retroperitoneal locations. However, this obstructed migration is generally benign, does not affect kidney function, and is not commonly associated with ischemia or abdominal pain.
A 33-year-old man is brought to the emergency department after being involved in a bar fight. Physical examination shows tenderness to palpation over the left side of the back. An x-ray of the chest shows a fracture of the 12th rib on the left side. Further evaluation is most likely to show which of the following injuries?
The kidneys normally lie in a paraspinal, retroperitoneal position that extends from T12–L3. The right kidney is displaced more inferiorly because of the liver. Inferior rib fractures (10–12th ribs) are commonly associated with solid organ injuries to the liver, spleen, and/or kidneys. This patient has sustained a fracture of the posterior aspect of the left 12th rib as is evident from the tenderness over his back and the x-ray findings, which makes a kidney laceration the most likely associated injury.
. Splenic injury is more common than kidney injury.
A 47-year-old man with bipolar I disorder and hypertension comes to the physician because of a 2-week history of increased thirst, urinary frequency, and sleep disturbance. He says that he now drinks up to 30 cups of water daily. He has smoked 2 packs of cigarettes daily for the past 20 years. Examination shows decreased skin turgor. Serum studies show a sodium concentration of 149 mEq/L, a potassium concentration of 4.1 mEq/L, and an elevated antidiuretic hormone concentration. His urine osmolality is 121 mOsm/kg H2O (low <300). Which of the following is the most likely explanation for these findings?
Increased serum antidiuretic hormone (ADH) in a patient with features of diabetes insipidus is suggestive of a nephrogenic cause. Nephrogenic DI is the most common complication of long-term use of lithium, the first-line mood stabilizer for patients with bipolar disorder. Lithium is believed to cause nephrogenic DI by interfering with ADH signaling in the collecting duct cells, which results in reduced expression of water channel aquaporin-2 in these cells.
This patient presents with proteinuria, hypoalbuminemia, edema, and hyperlipidemia – the defining features of nephrotic syndrome. Additionally, the radiographic findings combined with his recent weight loss and history of smoking are highly suggestive of lung cancer. Light microscopic examination of a kidney biopsy shows thickening of glomerular capillary loops and the basal membrane. Which of the following is the most likely diagnosis?
Membranous nephropathy is the most common cause of nephrotic syndrome in White adults. Although the majority of cases are idiopathic, the condition can arise in association with solid malignancies, such as lung cancer, particularly in patients > 65 years. Deposition of antibodies between podocytes and the basal membrane causes thickening of glomerular capillary loops and the basal membrane, which in turn leads to nephrotic syndrome.
This patient presents with features of nephritic syndrome (i.e., oliguria, dark urine due to hematuria, periorbital edema, and hypertension) after a recent skin infection, most likely caused by group A beta-hemolytic streptococci (GAS). The image shows an enlarged hypercellular glomerulus with numerous inflammatory cells, which is characteristic of glomerulonephritis. This patient presents with features of nephritic syndrome (i.e., oliguria, dark urine due to hematuria, periorbital edema, and hypertension) after a recent skin infection, most likely caused by group A beta-hemolytic streptococci (GAS). The image shows an enlarged hypercellular glomerulus with numerous inflammatory cells, which is characteristic of glomerulonephritis.
Elevated anti-DNase B titers indicate a recent infection by GAS. Infection with nephritogenic strains of GAS results in subepithelial immune complex deposition within the glomerular basement membrane (type III hypersensitivity reaction), which activates the complement system. This results in glomerular inflammation and nephritic syndrome, which is then known as poststreptococcal glomerulonephritis (PSGN). Although PSGN is more common in young children and older adults, it can occur at any age. Adults are more likely to suffer from lasting kidney damage after PSGN, while the vast majority (> 90%) of children will fully recover.
A 42-year-old man comes to the physician because of fatigue and decreased urination for the past 3 days. His creatinine is 2.5 mg/dL. This patient’s kidney biopsy shows crescent formation, a sign of rapidly progressive glomerulonephritis (RPGN). Which of the following mechanisms most likely contributed to this patient’s biopsy findings?
Fibrin formation inside the Bowman space is characteristic of RPGN. Damage to the glomerular capillary wall, basement membrane, and Bowman capsule can lead to leakage of plasma proteins and inflammatory cells (e.g., macrophages, T cells) from both the renal interstitium and plasma. The crescent is formed by coagulation factors that create a fibrin clot, and by the proliferation of cells, such as macrophages, fibroblasts, and endothelial cells.
A 54-year-old woman comes to the physician for a follow-up examination after presenting with elevated blood pressure readings during her last two visits. After her last visit 2 months ago, she tried controlling her hypertension with weight loss before starting medical therapy, but she has since been unable to lose any weight. Her pulse is 76/min, and blood pressure is 154/90 mm Hg on the right arm and 155/93 mm Hg on the left arm. She agrees to start treatment with a thiazide diuretic. In response to this treatment, which of the following is most likely to decrease?
Thiazide diuretics (e.g., hydrochlorothiazide) can increase serum calcium levels by decreasing the excretion of calcium in the urine. Other adverse effects include hypokalemia, hypomagnesemia, hyperglycemia, hyperlipidemia, and hyperuricemia. The inhibition of renal Na+-Cl- cotransporters in the early distal tubule causes a net urine loss of positive ions such as sodium. This is compensated by increased renal tubular reabsorption of calcium to maintain electrochemical balance
