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A 55-year-old male, with a history of diabetes and coronary heart disease, who had undergone a cardiac catheterization with the use of a radiocontrast agent 2days ago is admitted to the ER with flu-like syndrome including chills, nausea, vomiting, abdominal pain, fatigue and pulmonary congestion. His serum creatinine is elevated and he has proteinuria. He is admitted to the ICU with a tentative diagnosis of AKI due to radiocontrast nephropathy.

a. Radiocontrast agents are thought to exert their effects through decreased renal perfusion and through direct toxic effects on renal tubular structures. Explain how each of these contribute to the development of AKI.

b. Explain his elevated creatinine, proteinuria and pulmonary congestion.
Step 1/5

Radiocontrast-induced nephropathy is a renal injury caused due to contrast agent during radio-imaging.
Radiocontrast is often used to improve definition during radio imaging.

Explanation for step 1

The incidence of radiocontrast-induced nephropathy is up to 24 %
The risk factors for radiocontrast-induced nephropathy are:

Concomitant diabetes and hypertension
Age more than 75 years
Low blood pressure
Dehydration
The high volume of contrast
Hypoalbumenia
Use of other nephrotoxic drugs

Step 2/5

a) The pathophysiology of radiocontrast agent induce nephropathy is as follows:

Decreased renal hypoxia
Direct toxic effect on renal tubular structures

Explanation for step 2

Contrast agents cause an increase in the level of asymmetrical dimethylarginine.
This inhibits nitric oxide.
Nitric oxide is a vasodilator, antioxidant, and anti-inflammatory in nature.
At the same time, the contrast causes an increase in the adenosine and endothelin levels. These are vasoconstrictors.
The contrast by itself stimulates the smooth muscle in the media of the blood vessels and causes vasoconstriction.
The net effect is vasoconstriction. This leads to renal hypoxia.
This is particularly evident in the renal medulla.
The contrast increases the viscosity of blood and reduces the capacity of the RBCs to change shape. This adds to ischemia.
This leads to a reduced blood supply to the metabolically active cells of the renal tubules.
This leads to the release of oxygen-free radicals.
The contrast damage the cells of the proximal renal tubule.
This leads to a 25% increment in serum creatinine within 48 hours.
Acute deterioration in renal function (up to 7 days) is called acute kidney injury. History of Diabetes and Coronary Heart Disease Essay Example
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Step 3/5

b) Creatinine is produced by the muscles. It is formed from creatine.

Explanation for step 3

Creatinine moves freely out of the glomerular vessels into the tubules.
In the proximal convoluted tubule, 10 - 30% is secreted into the tubules.
Contrast causes damage to the renal tubules.
Therefore, the removal of creatinine in the urine is reduced.
This leads to an increase in the blood levels of creatinine in contrast-induced nephropathy.

Step 4/5

b) Diabetes can lead to proteinuria.

Explanation for step 4

Diabetes is characterized by hyperglycemia.
Hyperglycemia causes oxidative stress in the nephrons.
It causes afferent arteriolar vasodilation and efferent arteriolar vasoconstriction.
This lead to an increase in the pressure inside the glomerulus.
There is also mesangial expansion and apoptosis of the podocytes.
There is a thickening of the extracellular matrix
This leads to proteinuria.

Step 5/5

b) Pulmonary congestion may be due to direct injury to the lungs by the contrast.

Explanation for step 5

Pulmonary congestion occurs either due to cardiac causes or non-cardiac causes.
The cardiac cause is usually due to left heart failure. This leads to pulmonary venous congestion due to back pressure changes.
Non-cardiac causes for pulmonary congestion result from direct injury to the pulmonary capillaries.
Contrast causes pulmonary congestion via both the above-mentioned ways:

The contrast increases the intravascular volume.
A patient with coronary heart disease will not be able to tolerate the excess volume.
This can lead to pulmonary congestion.
At the same time, the contrast can cause damage to the vascular endothelium of the pulmonary capillaries.
This will lead to an increase in capillary permeability. Thus leading to pulmonary congestion.

Final answer

Therefore, multiple mechanism are responsible for contrast induced nephropathy. At the same time, the contrast also affects the lungs and lead to pulmonary edema. History of Diabetes and Coronary Heart Disease Essay Example

Expert Answer

A 55-year-old male, with a history of diabetes and coronary heart disease, who had undergone a cardiac catheterization with the use of a radiocontrast agent 2days ago is admitted to the ER with flu-like syndrome including chills, nausea, vomiting, abdominal pain, fatigue and pulmonary congestion. His serum creatinine is elevated and he has proteinuria. He is admitted to the ICU with a tentative diagnosis of AKI due to radiocontrast nephropathy. a. Radiocontrast agents are thought to exert their effects through decreased renal perfusion and through direct toxic effects on renal tubular structures. Explain how each of these contribute to the development of AKI. b. Explain his elevated creatinine, proteinuria and pulmonary congestion.

Step 1/5

Radiocontrast-induced nephropathy is a renal injury caused due to contrast agent during radio-imaging.

Radiocontrast is often used to improve definition during radio imaging.

Explanation for step 1

The incidence of radiocontrast-induced nephropathy is up to 24 %
The risk factors for radiocontrast-induced nephropathy are:

Concomitant diabetes and hypertension
Age more than 75 years
Low blood pressure
Dehydration
The high volume of contrast
Hypoalbumenia
Use of other nephrotoxic drugs

Step 2/5

a) The pathophysiology of radiocontrast agent induce nephropathy is as follows:

Decreased renal hypoxia
Direct toxic effect on renal tubular structures

Explanation for step 2

Contrast agents cause an increase in the level of asymmetrical dimethylarginine.
This inhibits nitric oxide.
Nitric oxide is a vasodilator, antioxidant, and anti-inflammatory in nature.
At the same time, the contrast causes an increase in the adenosine and endothelin levels. These are vasoconstrictors.
The contrast by itself stimulates the smooth muscle in the media of the blood vessels and causes vasoconstriction.
The net effect is vasoconstriction. This leads to renal hypoxia.
This is particularly evident in the renal medulla.
The contrast increases the viscosity of blood and reduces the capacity of the RBCs to change shape. This adds to ischemia.
This leads to a reduced blood supply to the metabolically active cells of the renal tubules.
This leads to the release of oxygen-free radicals.
The contrast damage the cells of the proximal renal tubule.
This leads to a 25% increment in serum creatinine within 48 hours.
Acute deterioration in renal function (up to 7 days) is called acute kidney injury. History of Diabetes and Coronary Heart Disease Essay Example
ORDER YOUR PAPER NOW

Step 3/5

b) Creatinine is produced by the muscles. It is formed from creatine.

Explanation for step 3

Creatinine moves freely out of the glomerular vessels into the tubules.
In the proximal convoluted tubule, 10 - 30% is secreted into the tubules.
Contrast causes damage to the renal tubules.
Therefore, the removal of creatinine in the urine is reduced.
This leads to an increase in the blood levels of creatinine in contrast-induced nephropathy.

Step 4/5

b) Diabetes can lead to proteinuria.

Explanation for step 4

Diabetes is characterized by hyperglycemia.
Hyperglycemia causes oxidative stress in the nephrons.
It causes afferent arteriolar vasodilation and efferent arteriolar vasoconstriction.
This lead to an increase in the pressure inside the glomerulus.
There is also mesangial expansion and apoptosis of the podocytes.
There is a thickening of the extracellular matrix
This leads to proteinuria.

Step 5/5

b) Pulmonary congestion may be due to direct injury to the lungs by the contrast.

Explanation for step 5

Pulmonary congestion occurs either due to cardiac causes or non-cardiac causes.
The cardiac cause is usually due to left heart failure. This leads to pulmonary venous congestion due to back pressure changes.
Non-cardiac causes for pulmonary congestion result from direct injury to the pulmonary capillaries.
Contrast causes pulmonary congestion via both the above-mentioned ways:
- The contrast increases the intravascular volume.
- A patient with coronary heart disease will not be able to tolerate the excess volume.
- This can lead to pulmonary congestion.
- At the same time, the contrast can cause damage to the vascular endothelium of the pulmonary capillaries.
- This will lead to an increase in capillary permeability. Thus leading to pulmonary congestion.

Final answer

Therefore, multiple mechanism are responsible for contrast induced nephropathy. At the same time, the contrast also affects the lungs and lead to pulmonary edema. History of Diabetes and Coronary Heart Disease Essay Example

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