Diabetic Nephropathy

Case Presentations

UA (Urine Dipstick)• Use as an initial screen for all patients• Negative to trace proteinuria requires

further testing for microalbuminuria• 1+ or greater proteinuria requires

further testing to quantitate proteinuria• Once a patient has microalbuminuria,

UA (urine dipstick) testing for gross proteinuria may be adequate although yearly testing for albuminuria may have become standard of care

Microalbuminuria

• Spot AM urine: Alb/Cr ratio .03-.3*• Timed urine collection: 20-200µg

albumin/min• 24 hour urine collection: 30-300

mg albumin in 24 hours

*This is the most practical test

Microalbumin TestingFactors that Cause False Positive Test

– poorly controlled diabetes– morbid obesity– acute illness, fever, UTI– pregnancy, menstruation– high protein diet– CHF– hematuria, major stress: surgery or

anesthesia

Incipient Nephropathy

Type 1 Diabetes– 2 out of 3 urine tests + for

microalbuminuria (start screening 5 years after the initial diagnosis)

– presence of proliferative diabetic retinopathy

– 80-90% of type 1 patients with microalbuminuria will progress to DN

Incipient Nephropathy

Type 2 Diabetes– 2 out of 3 urine tests + for

microalbuminuria (start screening at the time of diagnosis of diabetes)

– presence of diabetic retinopathy– 20-30% may have diabetic nephropathy

but not diabetic retinopathy– 25% may have a diagnosis of

nephropathy other than diabetic nephropathy

Macroalbuminuria• Spot AM urine: Alb/Cr ratio greater

than .3• Timed urine collection: greater than

200µg albumin/min• 24 hour urine collection: greater

than 300 mg albumin in 24 hours• If macroalbuminuria is present then

test for gross proteinuria

Gross Proteinuria• Defined as urine protein >500mg/24 hr.• Gold standard test is

– 24 hour urine collection for total protein and creatinine clearance

• Can also test protein/creatinine ratio– measures total mg protein/mg

creatinine– correlates 1:1 with a 24 hr urine in

grams/24 hr – less accurate in ARF, intersitial

nephritis, high degrees of proteinuria

Overt Diabetic Nephropathy

• Gold Standard is biopsy• Diagnosis can be made by clinical

history and exclusion of other renal disease

• Workup includes– Renal ultrasound for size, shape,

abnormalities– 24 hour urine for total protein and

creatinine clearance

Treatment• Lifestyle changes

– Lose weight– Stop smoking– Low salt diet for BP control– Low protein diet?

• Glycemic Control – Benefit in both Type 1 and Type 2

patients– Recommended: HbA1C <7.0%

(some say <6.5%)

Blood Pressure Control• Current ADA recommendations are

for blood pressure <130/80-85 (if nephropathy <125/75)

• Several randomized controlled trials indicate that improved blood pressure control decreases the rate of progression of renal disease in both type 1 and type 2 patients

ACE’s and ARB’s

• Angiotensin converting enzyme inhibitors and angiotensin receptor blocking agents have been shown in animal models and in randomized controlled trials to improve diabetic nephropathy

• Mechanism of action - ACE-inhibitors limit angiotensin II production by blocking angiotensin converting enzyme, ARB-agents block angiotensin II receptors

Case #1

Your first patient is a 25 year old young man with a 5 year history of type 1 diabetes. His urine dipstick is negative for protein. You check a spot AM urine alb/cr ratio which is .019. His blood pressure is 112/66. His HbA1C is 6.9.

Which is (are) true?1. The patient has early or incipient diabetic

nephropathy.

2. The patient should maintain a HbA1C of less than 7 to help protect his kidneys.

3. You should start the patient on an ACE inhibitor to protect his kidneys.

4. All of the above are true.

Patient #2

Your next patient is a 43 year old woman with a six year history of type 2 diabetes. A urine dip shows trace protein and a spot AM urine alb/cr ratio is .039. Her blood pressure is 135/80 and her HbA1C is 6.7.

Which is (are) not true?1. You should check the patient’s serum

creatinine and potassium.2. You should start the patient on an ACE

inhibitor if her K+ and Cr are okay. 3. You should check a 24 hour urine for total

protein and creatinine clearance.4. The patient has overt diabetic

nephropathy and should be referred to a nephrologist.

Case #3Your last patient is a 60 year old with HTN, dyslipidemia and newly diagnosed type 2 diabetes. A urine dip shows 2+ protein. He has a fever and his HbA1C is 10.3. His blood pressure is 140/88. He is taking HCTZ and glipizide.

Which is (are) true?1. You should get the patient’s diabetes

under better control before rechecking his urine.

2. A fever will not cause proteinuria.3. The patient’s blood pressure is under

good control.4. You should check the patient’s

potassium and creatinine.

Case #3

Three months later with exercise, metformin and enalapril your patient’s HbA1C is now 7.5 and his blood pressure is 135/85. A urine dip now shows 1+ protein.

Which is (are) true?1. You should check a 24 hour urine for

total protein and cr. cl.2. A spot AM urine albumin/creatinine

ratio correlates well with a 24 hour urine for total protein

3. The patient likely already has diabetic nephropathy and should be referred to a nephrologist.