Diabetic & Ischemic Nephropathy

Question 1

What is the definition of diabetic nephropathy? Select all that apply.

a) ACR >30mg/mmol
b) ACR >2.0mg/mmol
c) eGFR 1.0g/L
d) eGFR less than 60 ml/min

Answer 1

Diabetic nephropathy is considered when ACR>/= 2.0mg/mmol AND/OR eGFR less than 60 ml/min

Question 2

What happens to the GFR in the initiation of diabetic nephropathy?

Answer 2

Initially, the GFR increases (the kidneys start hyper-filtering; this is the first sign of kidney disease). Following this, the GFR comes back down to normal and declines as proteinuria increases.

Question 3

When should you consider a diagnosis other than diabetic nephropathy?

Answer 3

Consider an alternative diagnosis when the following features are present:

• extreme proteinuria (>6g/day)
• persistent hematuria of active urine
• rapidly falling eGFR
• low eGFR with little or no proteinuria
• no or few diabetic complications
• known duration of diabetes

Question 4

What are the potential causes of transient proteinuria?

Answer 4

Major exercise, menstruation, febrile illness, UTI, CHF, acute severe HTN, acute severe hyperglycaemia can all cause transient proteinuria. Therefore, you must assess for diabetic nephropathy when a patient is stable.

Question 5

What features add evidence to the diagnosis of diabetic nephropathy?

Answer 5

Suggestive of diabetic nephropathy: persistent albuminuria, bland urine sediment, slow progression of disease, low eGFR with over proteinuria, other complications of diabetes, known duration of diabetes >5 years

Question 6

When does the risk of nephropathy start in T1DM?

a) 1 year
b) 3 years
c) 5 years
d) 7 years
e) 10 years

Answer 6

e) 10 years

Question 7

What is the treatment for diabetic nephropathy?

Answer 7

1. Glycemic control (legacy effect)
2. ACE/ARBs
3. BP control

Question 8

By how much do ACEi reduce the risk of doubling of Cr or ESRD?

a) 10%
b) 20%
c) 30%
d) 40%
e) 50%

Answer 8

e) 50%

Question 9

When do patients with T2DM develop nephropathy?

a) 1 year
b) 3 years
c) 5 years
d) 7 years
e) 10 years

Answer 9

e) 10 years; however it takes longer to diagnose than T1DM so you have to start screening earlier!

Question 10

When should you combine ACEs and ARBs?

a) always
b) only if proteinuria is elevated
c) only if ACEs don’t do the job
d) only if they have an eGFR below 30
e) never

Answer 10

NEVER

Question 11

What type of tubular acidosis are patients with diabetic nephropathy subject to and why?

Answer 11

Type 4 RTA

Autonomic neuropathy results in decreased renin release which results in decrease aldosterone and ultimately potassium retention. This results in a Type 4 RTA.

Question 12

What is the definition of ischemic nephropathy?

Answer 12

Ischemic nephropathy = hypo-perfusion of kidney (usually due to atherosclerosis) leading to CKD; conditions that lead to hypo-perfusion

Question 13

What is the definition of renovascular disease (renal artery stenosis)?

Answer 13

Renovascular disease = narrowing of the large vessels resulting from atherosclerosis (or rarely, fibromuscular dysplasia)

Question 14

What is the pathogenesis of small vessel ischemic nephropathy?

Answer 14

Arterioles in the kidney will hypertrophy; HTN and other factors result in hyaline deposition. The lumen then shrinks and there is decreased blood flow to the glomerulus. There is ischemic collapse of capillary loops due to hypo-perfusion and thickening of Bowman’s capsule. There is myointimal thickening due to proliferation of cells and collagen deposition resulting in luminal narrowing. Small vessel nephropathy can result in FSGS or global sclerosis of the glomeruli.

Question 15

What are the RFs for ischemic nephropathy?

Answer 15

HTN, DM, dyslipidemia, smoking

Question 16

A 56 year old male has recently been diagnosed with hypertension. He presents to the ED with edema and oliguria and upon investigation you notice a 35% increase in his Cr since starting an ACEi. What finding would you look for on PE would help to make the diagnosis?

Answer 16

This patient’s creatinine increase is greater than expected and above 30% which is consistent with renal artery stenosis. On PE things that might help lead to a diagnosis of Renal Artery Stenosis include an abdominal bruit (esp. if systolic and diastolic). The patient may also present with flash pulmonary edema and have a history of uncontrollable HTN (>3 meds) or abrupt onset of HTN.

Question 17

What is the gold standard for diagnosis of Renal Artery Stenosis?

Answer 17

Angiogram; however contrast and invasive nature of the procedure is a RF for AKI so realistically U/S is used for diagnosis.

Question 18

What is the typical presentation of small vessel ischemic nephropathy?

Answer 18

• 60-80 yrs old
• History of RFs: HTN, DM, dyslipidemia, smoking
• Slowly progressiveCKD (>3 months)
• Bland urine (no blood and no protein)
• Normal imaging