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A 35 year-old Caucasian male presents with persistent swelling of both legs associated with dark colored urine for two months. He went to an emergency room 2 months ago for these complaints and was told that he has some protein and blood in the urine. He was treated with 3 days of levofloxacin. There is no other past medical history. No history of skin rash or joint swelling. On examination the blood pressure was 130/85 mm Hg and there was bilateral 1+ pedal edema. Rest of the physical examination was normal. Urine analysis showed 3+ proteinuria, 10-15 RBCs per high-power field, and occasional RBC cast. The BUN was 10 mg/dL, serum creatinine was 0.9 mg/dL. Antistreptolysin was negative, C3 level is decreased and C4 level is normal. Antinuclear antibodies, ANCA, hepatitis B and C serology were negative. 24-hour urine collection showed 2 g proteinuria and a kidney biopsy was performed. On light microscopy, kidney biopsy showed increase in the mesangial matrix and cellularity and glomerular basement membrane appeared irregularly thickened. Silver stain revealed duplication of glomerular basement membrane in multiple glomeruli. Immunofluorescence showed positive staining for C3, but negative for IgG, IgM and IgA. Electron microscopy revealed electron-dense deposits in the mesangium and sub-endothelial area. 

What is the most likely diagnosis?

A. Acute poststreptococcal glomerular nephritis
B. Diffuse proliferative lupus nephritis 
C. Dense deposit disease 
D. C3 glomerulopathy 
E.
Correct
The correct answer is D
C3 glomerulopathy

Explanation:

This patient has proteinuria, microscopic hematuria, hypertension and edema suggestive of acute nephritis of 2 months duration. The classic prototype of acute nephritis is acute post streptococcal glomerulonephritis. Typically in the acute post infective glomerular nephritis, complement levels normalize in 6 weeks and generally proteinuria and microhematuria resolve in approximately 6 weeks. Hence (Choice A) is wrong. This patient has hypocomplementemia and features of acute nephritis for 2 months suggesting that we should look for other causes of acute nephritis. 

Acute nephritis with low complement levels:
Post-infectious glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
C3 Nephropathy

Acute nephritis with normal complement levels:
IgA nephropathy
Thin basement membrane disease
Hereditary nephritis
HSP
Mesangial proliferative glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
Dense deposit disease

This patient is a male and ANA is negative. Lupus is mainly a disease affecting young women in third and fourth decade and most of them are ANA positive. A variety of glomerular pathologies are described, but immunofluorescence typically shows ‘full house’ pattern with positive IgG, IgM, IgA and C3. ANA negativity and not having the IF picture showing full house to suggest lupus nephritis makes lupus nephritis (Choice B) unlikely.

Dense deposit disease is type II MPGN and it mainly affects children and young adults. In the majority of patients there is circulating C3 nephritic factor. Immunofluorescence microscopy demonstrates C3 deposits, and EM shows characteristic sausage-shaped, wavy deposits along the glomerular basement membranes (GBM) and mesangium. Lack of typical EM appearance makes dense deposit disease (Choice C) unlikely.

C3 Glomerulopathy is a morphologic variant of MPGN type I. In “C3 glomerulopathy”, different light microscopy pathologies such as mesangioproliferative, membranoproliferative glomerulonephritis, diffuse proliferative glomerulonephritis, crescentic GN and Sclerosing GN has been described. C3 level is usually low and C4 level is normal. In Sclerosing disease, C3 level can also be normal. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits. Hence, the  correct choice is (Choice D).

C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.

Educational Objective:
C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.
C3 glomerulopathy is a morphologic variant of MPGN type I. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits.

IMPORTANT BOARD EXAM ADVICE:

1. Differentiate between DDD and C3GN
2. Know the glomerulonephritis with low and normal complement levels.
3. BOARD QUESTIONS will be asked on DDD and C3GN, so know it well.

Copyright © ABIM Exam World
Created On: 09/12/2017
Last Modified: 03/07/2021

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As per the JNC VIII committee recommendation, for individuals that are part of the African American population, including those with diabetes, the initial treatment should include a thiazide type diuretic or calcium channel blocker (CCB).  

Which of the following thiazide type diuretic is preferred as the initial antihypertensive therapy?

 

A. Hydrochlorthiazide 
B. Chlorthalidone 
C. Indapamide 
D. Metalazone 
E. Polythiazide 
Correct
The correct answer is B 
Chlothalidone

Explanation:

• Chlorthalidone at the same dose is approximately 1.5 to 2 times as potent as hydrochlorothiazide.

• Chlothalidone has a longer duration action than hydrochlorothiazide.

• There are No randomized clinical trials that directly compare outcomes in hypertensive patients treated with hydrochlorothiazide versus chlorthalidone. A multiple treatment (network) meta-analysis of nine trials including 50,946 patients was conducted in which hydrochlorothiazide and chlorthalidone were indirectly compared by evaluating their efficacy against common comparative drugs (ACE inhibitors were compared with hydrochlorothiazide in ANBP2 trial and with chlorthalidone in ALLHAT trial). The major findings of this meta-analysis showed that chlorthalidone significantly reduced the risk of cardiovascular events compared to hydrochlorothiazide (relative risk 0.79, 95% CI 0.72 to 0.88) and heart failure (relative risk 0.77, 95% CI 0.61 to 0.98). The authors calculated that 27 patients would need to be treated with chlorthalidone instead of hydrochlorothiazide over five years to prevent one cardiovascular event. Chlorthalidone remained superior to hydrochlorothiazide even after the meta-analysis was controlled for achieved office systolic blood pressure (relative risk for cardiovascular events 0.82, 95% CI 0.70 to 0.97). This finding may reflect the longer duration of action and lower nocturnal blood pressure associated with chlorthalidone.

• Multiple Risk Factor Intervention Trial (MRFIT) - Men Hypertensive 2392 were treated with chlorthalidone and 4049 were treated with hydrochlorothiazide. During six years of follow-up, cardiovascular events (defined as myocardial infarction, stroke, coronary artery bypass surgery, heart failure, left ventricular hypertrophy, peripheral artery disease, or angina) were significantly less common with chlorthalidone compared with hydrochlorothiazide (hazard ratio 0.79, 95% CI 0.68 to 0.92). Through the course of the study, systolic blood pressure and LDL cholesterol levels were also lower with chlorthalidone compared with hydrochlorothiazide. 

• Indapamide - is a thiazide like diuretic and has a half-life of 14-16 hours. This drug has been used in HYVET trial alone or in combination with perindropril in treatment of hypertension in patients more than 80 years old. Study showed 30% reduction in stroke, 39% reduction in the rate of death .21%in death from any cause, 23%reduction in CV death and 64%reduction in the rate of heart failure. The trial has shown careful BP lowering in very elderly is beneficial. Indapamide is not preferred over chlorthalidone.

• Metalazone - There are many studies with metalazone available. An important additional property is its effectiveness as a diuretic at lower GFR value. The duration of action is about 24 hours.
It is not preferred over chlorthalidone.

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Created On: 09/20/2017
Last Modified: 10/28/2024

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You are rounding on your patients in the dialysis unit and seeing a 65-year-old gentleman with ESRD due to chronic interstitial disease. He also has a history of diet-controlled diabetes mellitus and hypertension. His other past medical history is significant for dyslipidemia, coronary artery disease, hypothyroidism, gout and depression. He has been hospitalized in the recent past for swelling and pain of his right great toe. He was seen by the foot doctor, a scan was done and eventually the great toe had to be amputated.  He has been on hemodialysis 3 times a week. His weekly Kt/V is 1.9. You are conducting the monthly blood work review for this patient. You note that his hemoglobin has been persistently low for past few monthly blood draws. He is currently on 100 mcg of Darbepoetin weekly on dialysis. On enquiry there is no history of blood loss in the form of hematemesis, melena, hematochezia or hemoptysis. His active medication list includes Losartan, Atorvastatin, Calcitriol, multivitamin supplements, paroxetine, allopurinol, aspirin.

His pertinent blood work is as follows:

Test

Result

WBC

4500 cells /cumm

Hemoglobin

8.2 g/dL

Platelet count

450 thousand /cumm

Reticulocyte count

Normal

Iron

55 (range 50-150)

Total iron binding capacity

250 g/dl (range 250-310)

Transferrin saturation

20%

Ferritin

1400 ng/ml (range 20-235)

Haptoglobin

400 mg/dl (range 83-267)

Lactate dehydrogenase

240 U/L (range 80-225)

Total bilirubin

1.0 mg/dl

Folate

7 ng/ml (range 1.8-9.0)

B12

500 pg/ml (range 200-800)


Peripheral blood smear.

Normal RBC morphology, few burr cells.



Which of the following is true about this patient’s anemia?


Omitted

Correct Answer: Option C: This patient has chronically inflamed state which is contributing to his anemia.


Explanation:

10-15% of patients who have been receiving erythrocyte estimating agents (ESA) develop resistance. There are multiple reasons why ESRD patients develop resistance.


ESA resistance occurs due to the following reasons:

  1. Iron deficiency.

  2. Chronic inflammation.

  3. Under-dialysis.

  4. Hemolysis.

  5. Folate and B12 deficiency.

  6. Chronic blood loss.

  7. Anti EPO antibodies.

  8. Pure red cell aplasia.

  9. Failed chronic renal allograft.

  10. ACEI/ARB.

  11. Aluminum overload.

  12. Hyperparathyroidism.

  13. Hematological disorders or malignancy.


Option A: Incorrect option. ESRD is associated with erythropoietin deficiency. Patient has been initiated on ESA already. There is no point in measuring EPO levels. There is no evidence of measuring EPO levels in management of anemia in CKD.

Option B: Incorrect option. ESRD is an inflamed state. In inflammatory milieu there is increased production of Hepcidin. The hepatic iron-regulatory hormone Hepcidin and its receptor, the cellular iron exporter Ferroportin, constitute a feedback-regulated mechanism that maintains adequate plasma concentrations of iron-transferrin for erythropoiesis and other functions, ensures sufficient iron stores, and avoids iron toxicity. In chronic kidney disease, inflammation and impaired renal clearance increases plasma hepcidin, inhibiting duodenal iron absorption and sequestering iron in macrophages. These effects of hepcidin can cause systemic iron deficiency, decreased availability of iron for erythropoiesis, and resistance to endogenous and exogenous erythropoietin.

Choice C: Correct option. Refer explanation for option B.  He had pain, swelling of his right great toe, a foot doctor sees him, a bone scan is done and subsequently the amputation. All suggestive of an infective etiology probably osteomyelitis.There is a temporal relationship between patients’ anemia and underlying chronic inflammatory state.

The high ferritin is also suggestive of inflamed state.

Choice D: Incorrect option. Pure red cell aplasia, a form of severe ESA hypo-responsiveness mediated by anti-erythropoietin antibodies, was first reported with certain formulations of Epoetin alfa but has now been reported with all commercially available forms of ESA. This syndrome presents with rapid onset of severe anemia (hemoglobin <7 g/dl), severe reticulocytopenia (reticulocyte count <10,000/?l) and marked elevations in serum ferritin level (>1000 ng/ml) and transferrin saturation (>70%) resulting from low iron utilization. Pure red cell aplasia is unlikely given the absence of characteristic laboratory findings. Moreover, the patient did not receive Epoetin alfa.


Choice E: Incorrect option. Under-dialysis leads to anemia due the same mechanism mentioned earlier in option B. Under-dialysis worsens the uremic milieu which in turn leads to inflammatory state. This leads to anemia. Patient in this clinical vignette has been dialysed appropriately. His weekly Kt/V is 1.9, which is above the target goal of 1.7

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Created On: 10/22/2018
Last Modified: 04/17/2021

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A 35 year-old Caucasian male presents with persistent swelling of both legs associated with dark colored urine for two months. He went to an emergency room 2 months ago for these complaints and was told that he has some protein and blood in the urine. He was treated with 3 days of levofloxacin. There is no other past medical history. No history of skin rash or joint swelling. On examination the blood pressure was 130/85 mm Hg and there was bilateral 1+ pedal edema. Rest of the physical examination was normal. Urine analysis showed 3+ proteinuria, 10-15 RBCs per high-power field, and occasional RBC cast. The BUN was 10 mg/dL, serum creatinine was 0.9 mg/dL. Antistreptolysin was negative, C3 level is decreased and C4 level is normal. Antinuclear antibodies, ANCA, hepatitis B and C serology were negative. 24-hour urine collection showed 2 g proteinuria and a kidney biopsy was performed. On light microscopy, kidney biopsy showed increase in the mesangial matrix and cellularity and glomerular basement membrane appeared irregularly thickened. Silver stain revealed duplication of glomerular basement membrane in multiple glomeruli. Immunofluorescence showed positive staining for C3, but negative for IgG, IgM and IgA. Electron microscopy revealed electron-dense deposits in the mesangium and sub-endothelial area. 

What is the most likely diagnosis?

A. Acute poststreptococcal glomerular nephritis
B. Diffuse proliferative lupus nephritis 
C. Dense deposit disease 
D. C3 glomerulopathy 
E.
Correct
The correct answer is D
C3 glomerulopathy

Explanation:

This patient has proteinuria, microscopic hematuria, hypertension and edema suggestive of acute nephritis of 2 months duration. The classic prototype of acute nephritis is acute post streptococcal glomerulonephritis. Typically in the acute post infective glomerular nephritis, complement levels normalize in 6 weeks and generally proteinuria and microhematuria resolve in approximately 6 weeks. Hence (Choice A) is wrong. This patient has hypocomplementemia and features of acute nephritis for 2 months suggesting that we should look for other causes of acute nephritis. 

Acute nephritis with low complement levels:
Post-infectious glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
C3 Nephropathy

Acute nephritis with normal complement levels:
IgA nephropathy
Thin basement membrane disease
Hereditary nephritis
HSP
Mesangial proliferative glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
Dense deposit disease

This patient is a male and ANA is negative. Lupus is mainly a disease affecting young women in third and fourth decade and most of them are ANA positive. A variety of glomerular pathologies are described, but immunofluorescence typically shows ‘full house’ pattern with positive IgG, IgM, IgA and C3. ANA negativity and not having the IF picture showing full house to suggest lupus nephritis makes lupus nephritis (Choice B) unlikely.

Dense deposit disease is type II MPGN and it mainly affects children and young adults. In the majority of patients there is circulating C3 nephritic factor. Immunofluorescence microscopy demonstrates C3 deposits, and EM shows characteristic sausage-shaped, wavy deposits along the glomerular basement membranes (GBM) and mesangium. Lack of typical EM appearance makes dense deposit disease (Choice C) unlikely.

C3 Glomerulopathy is a morphologic variant of MPGN type I. In “C3 glomerulopathy”, different light microscopy pathologies such as mesangioproliferative, membranoproliferative glomerulonephritis, diffuse proliferative glomerulonephritis, crescentic GN and Sclerosing GN has been described. C3 level is usually low and C4 level is normal. In Sclerosing disease, C3 level can also be normal. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits. Hence, the  correct choice is (Choice D).

C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.

Educational Objective:
C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.
C3 glomerulopathy is a morphologic variant of MPGN type I. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits.

IMPORTANT BOARD EXAM ADVICE:

1. Differentiate between DDD and C3GN
2. Know the glomerulonephritis with low and normal complement levels.
3. BOARD QUESTIONS will be asked on DDD and C3GN, so know it well.

Copyright © ABIM Exam World
Created On: 09/12/2017
Last Modified: 03/07/2021

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As per the JNC VIII committee recommendation, for individuals that are part of the African American population, including those with diabetes, the initial treatment should include a thiazide type diuretic or calcium channel blocker (CCB).  

Which of the following thiazide type diuretic is preferred as the initial antihypertensive therapy?

 

A. Hydrochlorthiazide 
B. Chlorthalidone 
C. Indapamide 
D. Metalazone 
E. Polythiazide 
Correct
The correct answer is B 
Chlothalidone

Explanation:

• Chlorthalidone at the same dose is approximately 1.5 to 2 times as potent as hydrochlorothiazide.

• Chlothalidone has a longer duration action than hydrochlorothiazide.

• There are No randomized clinical trials that directly compare outcomes in hypertensive patients treated with hydrochlorothiazide versus chlorthalidone. A multiple treatment (network) meta-analysis of nine trials including 50,946 patients was conducted in which hydrochlorothiazide and chlorthalidone were indirectly compared by evaluating their efficacy against common comparative drugs (ACE inhibitors were compared with hydrochlorothiazide in ANBP2 trial and with chlorthalidone in ALLHAT trial). The major findings of this meta-analysis showed that chlorthalidone significantly reduced the risk of cardiovascular events compared to hydrochlorothiazide (relative risk 0.79, 95% CI 0.72 to 0.88) and heart failure (relative risk 0.77, 95% CI 0.61 to 0.98). The authors calculated that 27 patients would need to be treated with chlorthalidone instead of hydrochlorothiazide over five years to prevent one cardiovascular event. Chlorthalidone remained superior to hydrochlorothiazide even after the meta-analysis was controlled for achieved office systolic blood pressure (relative risk for cardiovascular events 0.82, 95% CI 0.70 to 0.97). This finding may reflect the longer duration of action and lower nocturnal blood pressure associated with chlorthalidone.

• Multiple Risk Factor Intervention Trial (MRFIT) - Men Hypertensive 2392 were treated with chlorthalidone and 4049 were treated with hydrochlorothiazide. During six years of follow-up, cardiovascular events (defined as myocardial infarction, stroke, coronary artery bypass surgery, heart failure, left ventricular hypertrophy, peripheral artery disease, or angina) were significantly less common with chlorthalidone compared with hydrochlorothiazide (hazard ratio 0.79, 95% CI 0.68 to 0.92). Through the course of the study, systolic blood pressure and LDL cholesterol levels were also lower with chlorthalidone compared with hydrochlorothiazide. 

• Indapamide - is a thiazide like diuretic and has a half-life of 14-16 hours. This drug has been used in HYVET trial alone or in combination with perindropril in treatment of hypertension in patients more than 80 years old. Study showed 30% reduction in stroke, 39% reduction in the rate of death .21%in death from any cause, 23%reduction in CV death and 64%reduction in the rate of heart failure. The trial has shown careful BP lowering in very elderly is beneficial. Indapamide is not preferred over chlorthalidone.

• Metalazone - There are many studies with metalazone available. An important additional property is its effectiveness as a diuretic at lower GFR value. The duration of action is about 24 hours.
It is not preferred over chlorthalidone.

Copyright © ABIM Exam World
Created On: 09/20/2017
Last Modified: 01/28/2021

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You are rounding on your patients in the dialysis unit and seeing a 65-year-old gentleman with ESRD due to chronic interstitial disease. He also has a history of diet-controlled diabetes mellitus and hypertension. His other past medical history is significant for dyslipidemia, coronary artery disease, hypothyroidism, gout and depression. He has been hospitalized in the recent past for swelling and pain of his right great toe. He was seen by the foot doctor, a scan was done and eventually the great toe had to be amputated.  He has been on hemodialysis 3 times a week. His weekly Kt/V is 1.9. You are conducting the monthly blood work review for this patient. You note that his hemoglobin has been persistently low for past few monthly blood draws. He is currently on 100 mcg of Darbepoetin weekly on dialysis. On enquiry there is no history of blood loss in the form of hematemesis, melena, hematochezia or hemoptysis. His active medication list includes Losartan, Atorvastatin, Calcitriol, multivitamin supplements, paroxetine, allopurinol, aspirin.

His pertinent blood work is as follows:

Test

Result

WBC

4500 cells /cumm

Hemoglobin

8.2 g/dL

Platelet count

450 thousand /cumm

Reticulocyte count

Normal

Iron

55 (range 50-150)

Total iron binding capacity

250 g/dl (range 250-310)

Transferrin saturation

20%

Ferritin

1400 ng/ml (range 20-235)

Haptoglobin

400 mg/dl (range 83-267)

Lactate dehydrogenase

240 U/L (range 80-225)

Total bilirubin

1.0 mg/dl

Folate

7 ng/ml (range 1.8-9.0)

B12

500 pg/ml (range 200-800)


Peripheral blood smear.

Normal RBC morphology, few burr cells.



Which of the following is true about this patient’s anemia?


Omitted

Correct Answer: Option C: This patient has chronically inflamed state which is contributing to his anemia.


Explanation:

10-15% of patients who have been receiving erythrocyte estimating agents (ESA) develop resistance. There are multiple reasons why ESRD patients develop resistance.


ESA resistance occurs due to the following reasons:

  1. Iron deficiency.

  2. Chronic inflammation.

  3. Under-dialysis.

  4. Hemolysis.

  5. Folate and B12 deficiency.

  6. Chronic blood loss.

  7. Anti EPO antibodies.

  8. Pure red cell aplasia.

  9. Failed chronic renal allograft.

  10. ACEI/ARB.

  11. Aluminum overload.

  12. Hyperparathyroidism.

  13. Hematological disorders or malignancy.


Option A: Incorrect option. ESRD is associated with erythropoietin deficiency. Patient has been initiated on ESA already. There is no point in measuring EPO levels. There is no evidence of measuring EPO levels in management of anemia in CKD.

Option B: Incorrect option. ESRD is an inflamed state. In inflammatory milieu there is increased production of Hepcidin. The hepatic iron-regulatory hormone Hepcidin and its receptor, the cellular iron exporter Ferroportin, constitute a feedback-regulated mechanism that maintains adequate plasma concentrations of iron-transferrin for erythropoiesis and other functions, ensures sufficient iron stores, and avoids iron toxicity. In chronic kidney disease, inflammation and impaired renal clearance increases plasma hepcidin, inhibiting duodenal iron absorption and sequestering iron in macrophages. These effects of hepcidin can cause systemic iron deficiency, decreased availability of iron for erythropoiesis, and resistance to endogenous and exogenous erythropoietin.

Choice C: Correct option. Refer explanation for option B.  He had pain, swelling of his right great toe, a foot doctor sees him, a bone scan is done and subsequently the amputation. All suggestive of an infective etiology probably osteomyelitis.There is a temporal relationship between patients’ anemia and underlying chronic inflammatory state.

The high ferritin is also suggestive of inflamed state.

Choice D: Incorrect option. Pure red cell aplasia, a form of severe ESA hypo-responsiveness mediated by anti-erythropoietin antibodies, was first reported with certain formulations of Epoetin alfa but has now been reported with all commercially available forms of ESA. This syndrome presents with rapid onset of severe anemia (hemoglobin <7 g/dl), severe reticulocytopenia (reticulocyte count <10,000/?l) and marked elevations in serum ferritin level (>1000 ng/ml) and transferrin saturation (>70%) resulting from low iron utilization. Pure red cell aplasia is unlikely given the absence of characteristic laboratory findings. Moreover, the patient did not receive Epoetin alfa.


Choice E: Incorrect option. Under-dialysis leads to anemia due the same mechanism mentioned earlier in option B. Under-dialysis worsens the uremic milieu which in turn leads to inflammatory state. This leads to anemia. Patient in this clinical vignette has been dialysed appropriately. His weekly Kt/V is 1.9, which is above the target goal of 1.7

Copyright © ABIM Exam World
Created On: 10/22/2018
Last Modified: 04/17/2021

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A 35 year-old Caucasian male presents with persistent swelling of both legs associated with dark colored urine for two months. He went to an emergency room 2 months ago for these complaints and was told that he has some protein and blood in the urine. He was treated with 3 days of levofloxacin. There is no other past medical history. No history of skin rash or joint swelling. On examination the blood pressure was 130/85 mm Hg and there was bilateral 1+ pedal edema. Rest of the physical examination was normal. Urine analysis showed 3+ proteinuria, 10-15 RBCs per high-power field, and occasional RBC cast. The BUN was 10 mg/dL, serum creatinine was 0.9 mg/dL. Antistreptolysin was negative, C3 level is decreased and C4 level is normal. Antinuclear antibodies, ANCA, hepatitis B and C serology were negative. 24-hour urine collection showed 2 g proteinuria and a kidney biopsy was performed. On light microscopy, kidney biopsy showed increase in the mesangial matrix and cellularity and glomerular basement membrane appeared irregularly thickened. Silver stain revealed duplication of glomerular basement membrane in multiple glomeruli. Immunofluorescence showed positive staining for C3, but negative for IgG, IgM and IgA. Electron microscopy revealed electron-dense deposits in the mesangium and sub-endothelial area. 

What is the most likely diagnosis?

A. Acute poststreptococcal glomerular nephritis
B. Diffuse proliferative lupus nephritis 
C. Dense deposit disease 
D. C3 glomerulopathy 
E.
Correct
The correct answer is D
C3 glomerulopathy

Explanation:

This patient has proteinuria, microscopic hematuria, hypertension and edema suggestive of acute nephritis of 2 months duration. The classic prototype of acute nephritis is acute post streptococcal glomerulonephritis. Typically in the acute post infective glomerular nephritis, complement levels normalize in 6 weeks and generally proteinuria and microhematuria resolve in approximately 6 weeks. Hence (Choice A) is wrong. This patient has hypocomplementemia and features of acute nephritis for 2 months suggesting that we should look for other causes of acute nephritis. 

Acute nephritis with low complement levels:
Post-infectious glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
C3 Nephropathy

Acute nephritis with normal complement levels:
IgA nephropathy
Thin basement membrane disease
Hereditary nephritis
HSP
Mesangial proliferative glomerulonephritis
Lupus nephritis
Membranoproliferative glomerular nephritis
Mixed cryoglobulinemia
Dense deposit disease

This patient is a male and ANA is negative. Lupus is mainly a disease affecting young women in third and fourth decade and most of them are ANA positive. A variety of glomerular pathologies are described, but immunofluorescence typically shows ‘full house’ pattern with positive IgG, IgM, IgA and C3. ANA negativity and not having the IF picture showing full house to suggest lupus nephritis makes lupus nephritis (Choice B) unlikely.

Dense deposit disease is type II MPGN and it mainly affects children and young adults. In the majority of patients there is circulating C3 nephritic factor. Immunofluorescence microscopy demonstrates C3 deposits, and EM shows characteristic sausage-shaped, wavy deposits along the glomerular basement membranes (GBM) and mesangium. Lack of typical EM appearance makes dense deposit disease (Choice C) unlikely.

C3 Glomerulopathy is a morphologic variant of MPGN type I. In “C3 glomerulopathy”, different light microscopy pathologies such as mesangioproliferative, membranoproliferative glomerulonephritis, diffuse proliferative glomerulonephritis, crescentic GN and Sclerosing GN has been described. C3 level is usually low and C4 level is normal. In Sclerosing disease, C3 level can also be normal. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits. Hence, the  correct choice is (Choice D).

C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.

Educational Objective:
C3 glomerulopathy can present with varying degrees of proteinuria, azotemia and can advance to ESRD. It can recur after transplantation.
C3 glomerulopathy is a morphologic variant of MPGN type I. The distinct feature of this is that IF shows exclusively C3 deposits, without any immunoglobulins. EM does not show sausage shaped intra-membranous deposits.

IMPORTANT BOARD EXAM ADVICE:

1. Differentiate between DDD and C3GN
2. Know the glomerulonephritis with low and normal complement levels.
3. BOARD QUESTIONS will be asked on DDD and C3GN, so know it well.

Copyright © ABIM Exam World
Created On: 09/12/2017
Last Modified: 03/07/2021

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As per the JNC VIII committee recommendation, for individuals that are part of the African American population, including those with diabetes, the initial treatment should include a thiazide type diuretic or calcium channel blocker (CCB).  

Which of the following thiazide type diuretic is preferred as the initial antihypertensive therapy?

 

A. Hydrochlorthiazide 
B. Chlorthalidone 
C. Indapamide 
D. Metalazone 
E. Polythiazide 
Correct
The correct answer is B 
Chlothalidone

Explanation:

• Chlorthalidone at the same dose is approximately 1.5 to 2 times as potent as hydrochlorothiazide.

• Chlothalidone has a longer duration action than hydrochlorothiazide.

• There are No randomized clinical trials that directly compare outcomes in hypertensive patients treated with hydrochlorothiazide versus chlorthalidone. A multiple treatment (network) meta-analysis of nine trials including 50,946 patients was conducted in which hydrochlorothiazide and chlorthalidone were indirectly compared by evaluating their efficacy against common comparative drugs (ACE inhibitors were compared with hydrochlorothiazide in ANBP2 trial and with chlorthalidone in ALLHAT trial). The major findings of this meta-analysis showed that chlorthalidone significantly reduced the risk of cardiovascular events compared to hydrochlorothiazide (relative risk 0.79, 95% CI 0.72 to 0.88) and heart failure (relative risk 0.77, 95% CI 0.61 to 0.98). The authors calculated that 27 patients would need to be treated with chlorthalidone instead of hydrochlorothiazide over five years to prevent one cardiovascular event. Chlorthalidone remained superior to hydrochlorothiazide even after the meta-analysis was controlled for achieved office systolic blood pressure (relative risk for cardiovascular events 0.82, 95% CI 0.70 to 0.97). This finding may reflect the longer duration of action and lower nocturnal blood pressure associated with chlorthalidone.

• Multiple Risk Factor Intervention Trial (MRFIT) - Men Hypertensive 2392 were treated with chlorthalidone and 4049 were treated with hydrochlorothiazide. During six years of follow-up, cardiovascular events (defined as myocardial infarction, stroke, coronary artery bypass surgery, heart failure, left ventricular hypertrophy, peripheral artery disease, or angina) were significantly less common with chlorthalidone compared with hydrochlorothiazide (hazard ratio 0.79, 95% CI 0.68 to 0.92). Through the course of the study, systolic blood pressure and LDL cholesterol levels were also lower with chlorthalidone compared with hydrochlorothiazide. 

• Indapamide - is a thiazide like diuretic and has a half-life of 14-16 hours. This drug has been used in HYVET trial alone or in combination with perindropril in treatment of hypertension in patients more than 80 years old. Study showed 30% reduction in stroke, 39% reduction in the rate of death .21%in death from any cause, 23%reduction in CV death and 64%reduction in the rate of heart failure. The trial has shown careful BP lowering in very elderly is beneficial. Indapamide is not preferred over chlorthalidone.

• Metalazone - There are many studies with metalazone available. An important additional property is its effectiveness as a diuretic at lower GFR value. The duration of action is about 24 hours.
It is not preferred over chlorthalidone.

Copyright © ABIM Exam World
Created On: 09/20/2017
Last Modified: 01/28/2021

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You are rounding on your patients in the dialysis unit and seeing a 65-year-old gentleman with ESRD due to chronic interstitial disease. He also has a history of diet-controlled diabetes mellitus and hypertension. His other past medical history is significant for dyslipidemia, coronary artery disease, hypothyroidism, gout and depression. He has been hospitalized in the recent past for swelling and pain of his right great toe. He was seen by the foot doctor, a scan was done and eventually the great toe had to be amputated.  He has been on hemodialysis 3 times a week. His weekly Kt/V is 1.9. You are conducting the monthly blood work review for this patient. You note that his hemoglobin has been persistently low for past few monthly blood draws. He is currently on 100 mcg of Darbepoetin weekly on dialysis. On enquiry there is no history of blood loss in the form of hematemesis, melena, hematochezia or hemoptysis. His active medication list includes Losartan, Atorvastatin, Calcitriol, multivitamin supplements, paroxetine, allopurinol, aspirin.

His pertinent blood work is as follows:

Test

Result

WBC

4500 cells /cumm

Hemoglobin

8.2 g/dL

Platelet count

450 thousand /cumm

Reticulocyte count

Normal

Iron

55 (range 50-150)

Total iron binding capacity

250 g/dl (range 250-310)

Transferrin saturation

20%

Ferritin

1400 ng/ml (range 20-235)

Haptoglobin

400 mg/dl (range 83-267)

Lactate dehydrogenase

240 U/L (range 80-225)

Total bilirubin

1.0 mg/dl

Folate

7 ng/ml (range 1.8-9.0)

B12

500 pg/ml (range 200-800)


Peripheral blood smear.

Normal RBC morphology, few burr cells.



Which of the following is true about this patient’s anemia?


Omitted

Correct Answer: Option C: This patient has chronically inflamed state which is contributing to his anemia.


Explanation:

10-15% of patients who have been receiving erythrocyte estimating agents (ESA) develop resistance. There are multiple reasons why ESRD patients develop resistance.


ESA resistance occurs due to the following reasons:

  1. Iron deficiency.

  2. Chronic inflammation.

  3. Under-dialysis.

  4. Hemolysis.

  5. Folate and B12 deficiency.

  6. Chronic blood loss.

  7. Anti EPO antibodies.

  8. Pure red cell aplasia.

  9. Failed chronic renal allograft.

  10. ACEI/ARB.

  11. Aluminum overload.

  12. Hyperparathyroidism.

  13. Hematological disorders or malignancy.


Option A: Incorrect option. ESRD is associated with erythropoietin deficiency. Patient has been initiated on ESA already. There is no point in measuring EPO levels. There is no evidence of measuring EPO levels in management of anemia in CKD.

Option B: Incorrect option. ESRD is an inflamed state. In inflammatory milieu there is increased production of Hepcidin. The hepatic iron-regulatory hormone Hepcidin and its receptor, the cellular iron exporter Ferroportin, constitute a feedback-regulated mechanism that maintains adequate plasma concentrations of iron-transferrin for erythropoiesis and other functions, ensures sufficient iron stores, and avoids iron toxicity. In chronic kidney disease, inflammation and impaired renal clearance increases plasma hepcidin, inhibiting duodenal iron absorption and sequestering iron in macrophages. These effects of hepcidin can cause systemic iron deficiency, decreased availability of iron for erythropoiesis, and resistance to endogenous and exogenous erythropoietin.

Choice C: Correct option. Refer explanation for option B.  He had pain, swelling of his right great toe, a foot doctor sees him, a bone scan is done and subsequently the amputation. All suggestive of an infective etiology probably osteomyelitis.There is a temporal relationship between patients’ anemia and underlying chronic inflammatory state.

The high ferritin is also suggestive of inflamed state.

Choice D: Incorrect option. Pure red cell aplasia, a form of severe ESA hypo-responsiveness mediated by anti-erythropoietin antibodies, was first reported with certain formulations of Epoetin alfa but has now been reported with all commercially available forms of ESA. This syndrome presents with rapid onset of severe anemia (hemoglobin <7 g/dl), severe reticulocytopenia (reticulocyte count <10,000/?l) and marked elevations in serum ferritin level (>1000 ng/ml) and transferrin saturation (>70%) resulting from low iron utilization. Pure red cell aplasia is unlikely given the absence of characteristic laboratory findings. Moreover, the patient did not receive Epoetin alfa.


Choice E: Incorrect option. Under-dialysis leads to anemia due the same mechanism mentioned earlier in option B. Under-dialysis worsens the uremic milieu which in turn leads to inflammatory state. This leads to anemia. Patient in this clinical vignette has been dialysed appropriately. His weekly Kt/V is 1.9, which is above the target goal of 1.7

Copyright © ABIM Exam World
Created On: 10/22/2018
Last Modified: 04/17/2021

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