Study Points
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Study Points
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- Outline the epidemiology of diabetes and renal disease in the United States.
- Identify criteria for the diagnosis of diabetes.
- Discuss the essential functions of the kidney.
- Evaluate the causes, diagnosis, and treatment of acute renal failure.
- Analyze the various stages of chronic kidney disease, including diabetic nephropathy.
- Utilize standards of care for the treatment and prevention of renal disease in patients with diabetes.
- Discuss the educational needs for patients with diabetes to prevent or delay renal disease.
Diabetes is the leading cause of kidney failure, accounting for what percentage of new cases?
Click to ReviewDiabetes is the leading cause of kidney failure in the United States, accounting for 44% of new cases [2]. In 2018, 131,636 individuals in the United States began treatment for end-stage renal disease requiring dialysis or transplantation [3]. In the United States, annual end-stage renal disease costs are estimated to be $49.2 billion, with a greater incidence and associated cost among racial minorities [3].
By 2025, what percentage of Americans are expected to have a diagnosis of diabetes or impaired glucose tolerance?
Click to ReviewAccording to the American Diabetes Association (ADA), as of 2020, 10.5% of the U.S. population, or 34.2 million Americans, have a diagnosis of diabetes. In addition, an estimated 7.3 million people have diabetes but remain undiagnosed [7]. By 2025, it is predicted that 15% to 20% of all Americans will have a diagnosis of diabetes or impaired glucose tolerance [8].
All of the following are diagnostic criteria for type 2 diabetes, EXCEPT:
Click to ReviewDIAGNOSTIC CRITERIA FOR TYPE 2 DIABETES
Stage Fasting Plasma Glucose Level Two-Hour Postprandial Plasma Glucose Level Glycated Hemoglobin (HbA1c) Euglycemia ≤100 mg/dL <140 mg/dL <5.7% Prediabetes >100 mg/dL but <126 mg/dL ≥140 mg/dL but <200 mg/dL 5.7% to 6.4% Diabetesa ≥126 mg/dL ≥200 mg/dL ≥6.5% aA random blood glucose level ≥200 mg/dL with symptoms of hyperglycemia is also indicative of diabetes. The approximate mass cutoff of substances for filtration in the kidneys is
Click to ReviewIt is approximated that the glomerular filtration rate (GFR) in a healthy individual with two properly functioning kidneys is 90–120 mL/min/1.73 m2 [20]. The approximate mass cutoff of substances for filtration is 70 kDa [21]. Substances greater than the 70 kDa cutoff are often retained during filtration; smaller particles are excreted in the urine.
What portion of the nephron is formed by the descending and ascending limbs of the renal tubule?
Click to ReviewTypically, approximately 30 mL/min of isotonic filtration is delivered to the loop of Henle, where a countercurrent multiplier mechanism achieves concentration of the urine [21]. The loop of Henle is the portion of the nephron formed by the descending and ascending limbs of the renal tubule [20]. This loop passes down into the medulla of the kidney, where secretion of sodium, chloride, and urea takes place. The thick ascending limb is impermeable to water but allows resorption of sodium, chloride, potassium, calcium, and bicarbonate. Due to the low water and high solute resorption in the loop of Henle, the filtration leaves the ascending limb hypo-osmotic [23].
The kidneys maintain the circulating blood volume by fluid balancing and by altering peripheral vascular resistance via the
Click to ReviewThe kidneys maintain the circulating blood volume by fluid balancing and by altering peripheral vascular resistance via the angiotensin-aldosterone system [23]. First, the sodium concentration in the proximal tubular fluid is sensed at the macula densa, part of the juxtaglomerular apparatus. The juxtaglomerular apparatus also assesses the perfusion pressure, an important indicator of intravascular volume status under normal circumstances. Through the action of these two sensors, either low sodium or low perfusion pressure acts as a stimulus to renin release [21]. Renin, a protease made in the juxtaglomerular cells, cleaves angiotensinogen in the blood to generate angiotensin I, which is then cleaved to angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II raises blood pressure by triggering vasoconstriction directly and by stimulating aldosterone secretion, resulting in sodium and water retention by the collecting duct [20]. All of these effects expand the extracellular fluid and consequently renal perfusion pressure, completing a homeostatic negative feedback loop that alleviates the initial stimulus for renin release [21].
Sympathetic innervation by the renal nerves influences
Click to ReviewThere are other clinically important adaptations to injury. Poor renal perfusion from any cause results in responses that improve perfusion through afferent arteriolar vasodilation and efferent arteriolar vasoconstriction in response to hormonal and neural cues [21]. These regulatory effects are reinforced by inputs sensing sodium balance. Alteration of sodium balance is another way to influence blood pressure and renal perfusion pressure [22]. Sympathetic innervation by the renal nerves influences renin release. Renal prostaglandins play an important role in vasodilation, particularly in individuals with chronically poor renal perfusion [21].
The most common origin of acute renal failure is
Click to ReviewAcute renal failure is a heterogeneous group of disorders characterized by widespread, rapid deterioration of renal function, resulting in accumulation of nitrogenous wastes in the blood that customarily would be excreted in the urine [21]. The most common origin of acute renal failure is impaired renal blood flow. In these patients, the GFR decreases in response to lower filtration pressures. Diminished perfusion can result from renal vasoconstriction, hypotension, hypovolemia, hemorrhage, or inadequate cardiac output [24].
Which of the following is NOT one of the three etiologic categories of acute renal failure?
Click to ReviewThere are three etiologic categories of acute renal failure: prerenal, intrarenal, and postrenal.
What condition is defined as a constellation of symptoms caused as a result of declining renal function and the accumulation of toxins within the plasma?
Click to ReviewThe clinical manifestations of chronic renal failure are often described using the term uremia. Uremia refers to a number of symptoms caused as a result of declining renal function and the accumulation of toxins in the plasma [24]. It has a number of effects on metabolism, including a decrease in a basal body temperature (perhaps due to decreased sodium, potassium, and ATP activity) and diminished lipoprotein lipase activity with accelerated atherosclerosis [21].
Excretory failure results in fluid shifts and includes decreased intracellular
Click to ReviewExcretory failure also results in fluid shifts, with increased intracellular sodium and water and decreased intracellular potassium. These alterations may contribute to subtle alterations in the function of a host of enzymes and transport systems [21].
What is a well-known marker of poor renal outcomes in individuals with type 2 diabetes?
Click to ReviewAlbuminuria is a well-known marker of poor renal outcomes in individuals with type 2 diabetes [31]. Persistent albuminuria is present in the earliest stage of nephropathy in type 1 diabetes and is a marker for development of nephropathy in type 2 diabetes [21]. Albuminuria has been shown to be a predictor of poor cardiovascular outcomes; therefore, serum albumin should be measured in all individuals with diabetes and hypertension and steps should be taken to suppress albuminuria to prevent further renal and cardiovascular events [31].
Which of the following is a classic feature of diabetic damage to the kidney?
Click to ReviewKimmelstiel Wilson nodules (nodular glomerulosclerosis) are a classic feature of diabetic damage to the kidney [32]. If Kimmelstiel Wilson nodes are present on biopsy, this is positive for diabetic nephropathy. The pathology of these nodes is related to histologic renal changes [5]. Progressive histologic changes in glomeruli are indistinguishable in type 1 and type 2 diabetes and occur to some degree in the majority of individuals [33]. The mesangium surrounding the glomerular vessels is increased due to the deposition of basement membrane-like material and can encroach on the glomerular vessels; the afferent and efferent glomerular arteries are also sclerosed. Glomerulosclerosis is usually diffuse; however, in some cases, it is associated with nodular sclerosis [33].
Changes in circulating levels of angiotensin II, catecholamines, and prostaglandins, or altered responsiveness to these vasoactive hormones, may result in
Click to ReviewResearch has demonstrated that hypertension, hyperglycemia, and high triglyceride concentrations are associated with an elevation in albumin-to-creatinine level independent of the type of diabetes [34]. Glucagon and growth hormone are both elevated in poorly controlled diabetes and have been shown to produce glomerular hyperfiltration, a phase that generally precedes glomerular alterations in patients with type 1 diabetes. Changes in circulating levels of angiotensin II, catecholamines, and prostaglandins, or altered responsiveness to these vasoactive hormones, may also result in hyperfiltration [1]. It is unclear whether this early hyperfiltration phase occurs in type 2 diabetes. It has been proposed that the presence of atherosclerotic lesions in older individuals with type 2 diabetes may prevent hyperfiltration and thus account for the lower incidence of overt clinical nephropathy in these individuals [35,36,37].
Diabetic nephropathy is defined clinically by the presence of more than
Click to ReviewIf glomerular lesions worsen, proteinuria increases and overt nephropathy develops. Diabetic nephropathy is defined clinically by the presence of more than 300–500 mg of urinary protein per day, an amount that can be detected by routine urinalysis [1]. In diabetic nephropathy, proteinuria continues to increase as renal function decreases. Therefore, end-stage renal disease is preceded by massive, nephritic-range proteinuria (greater than 4 mg/dL) [1]. Renal hemodynamic changes play a role in the pathogenesis of diabetic kidney disease.
In the presence of diabetic nephropathy, the recommended target blood pressure is less than or equal to
Click to ReviewBlood pressure management is also an important part of preventing renal disease in patients with diabetes. A target blood pressure of less than 130/80 mm Hg has been advised. However, tighter control is necessary in the presence of nephropathy; 120/70 mm Hg is suggested for these patients [1].
Which hormone stimulates the bone marrow to produce red blood cells?
Click to ReviewAnemia may occur in individuals with diabetic nephropathy even prior to the onset of advanced renal failure. This tendency is the result of erythropoietin deficiency [54]. Erythropoietin, typically manufactured in the kidney, is a hormone that stimulates the bone marrow to produce red blood cells [1]. Erythropoiesis-stimulating agent treatment should be initiated when hemoglobin levels are less than 11 g/dL, with a target hemoglobin level of 11–12 g/dL and a target hematocrit of 30% to 33% [56]. The potential risk of hypertension with erythropoietin therapy should be taken into consideration prior to initiating treatment [54,57]. Monthly hematocrit measurements are necessary during therapy so the dosage can be titrated as necessary. Measurements of serum iron and ferritin levels are recommended before initiating erythropoietin therapy and periodically during treatment to determine whether iron therapy should be initiated.
Contraindications to hemodialysis include all of the following, EXCEPT:
Click to ReviewHemodialysis is contraindicated if any of the following are present [23]:
Hemodynamic instability
Inability to anticoagulate
Lack of access to circulation
Kidney transplant can be performed using a kidney from all of the following, EXCEPT:
Click to ReviewKidney transplant can be performed using a kidney from a living relative donor, a living unrelated donor, or a suitable cadaveric donor [1]. Allocation of all transplants in the United States is managed by the United Network for Organ Sharing (UNOS). Kidney transplant guidelines place the highest considerations on histocompatibility and time spent on the transplant list [76]. The median adult wait time for a cadaver kidney is just over four years [3]. When the kidney is procured from the donor or cadaver, the ureter, renal vein, and renal artery are dissected, leaving as much length as possible [23].
In type 2 diabetes, screening of kidney function should begin
Click to ReviewAn intensive and multifactorial management approach is required for patients with diabetes and renal disease in order to address all risk determinants. This strategy should include lifestyle modifications (e.g., smoking cessation, weight management and reduction, increased physical activity, dietary changes) coupled with therapeutic achievement of evidence-based blood pressure, blood glucose, and lipid goals [77]. All individuals with type 1 or type 2 diabetes must be educated regarding the need for screening to assess kidney function regularly. In patients with type 1 diabetes, screening should be completed within five years of diagnosis and then annually thereafter. For patients with type 2 diabetes, screening should begin at diagnosis and continue annually thereafter [1].
- 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.