Kidney complications

Kidney Complications

Diabetic Nephropathy

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Diabetic nephropathy is detected clinically by the presence of persistent microalbuminuria or proteinuria. The peak incidence of nephropathy is usually 15-25 years following onset of diabetes in type 1 but may be present at diagnosis in type 2. The lifetime risk of developing diabetic nephropathy is about 25% in type 1 diabetes and 15% in type 2 diabetes. Risk factors predisposing to diabetic nephropathy include poor glycaemic control, hypertension, smoking and a family history of vascular disease. The presence of nephropathy is an independent and powerful predictor of chronic renal failure, macrovascular disease and death. Screening is vital as early detection and effective treatment can slow progression of renal failure and identify those at particularly high vascular risk. The possibility of non-diabetic renal disease should be considered if atypical features, including haematuria, absence of retinopathy and short duration of type 1 diabetes are present
Stages of Diabetic Renal Disease:
Stages
Laboratory Features

Increased urinary albumin excretion rate (microalbuminuria) Normal serum creatinine / eGFR
Serum creatinine normal or minimally elevated
Microalbuminuria and Proteinuria
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Microalbuminuria refers to urine albumin concentrations that are below the limit of detection of routine
urine dipsticks.
Proteinuria refers to urine albumin concentrations that are detectable by routine dipsticks.
In Type I and Type 2 diabetes, persistent microalbuminuria, is a marker of early diabetic nephropathy, premature macrovascular disease and death. Microalbuminuria in Type 1 and 2 diabetes should be viewed as an additional and independent cardiovascular risk factor. Co-existing coronary heart disease (CHD) risk factors should be treated aggressively in all patients who have persistent microalbuminuria. In both types of diabetes, improved diabetic control (Target HbA1c ≤ 7% or 53 mmol/mol) and
particularly aggressive anti-hypertensive therapy should retard the progression of nephropathy.
All patients with nephropathy should be treated with a statin, probably aspirin, and strongly advised to stop smoking. Who should be tested?

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Test all patients over the age of 12 annually for microalbuminuria in patients who are dipstick negative
for urinary protein.

Which sample should be sent and what should be requested?
The first voided morning urine sample in a clean universal container should be sent.

• This is for measurement of urinary albumin:creatinine ratio (ACR). An ACR > 2.5 mg/mmol in men or
>3.5 mg/mmol in women equates to microalbuminuria if present on 2 out of 3 occasions over 3
months. A single elevated ACR should prompt two or more further samples to confirm or refute the
diagnosis.
• In those with confirmed microalbuminuria repeat testing is indicated as a lowering of ACR indicates a An ACR >30 mg/mmol indicates diabetic nephropathy.

Samples should NOT be sent from patients who have evidence of UTI (nitrite positive).
For those who display dipstick positive proteinuria (more than ++) a specimen of urine should be sent for the
measurement of a protein:creatinine ratio (PCR). Random urine samples may be used but have a higher
false positive rate.

Interpretation of Results

DIAGNOSIS
ACR (mg/mmol)
Negative
Microalbuminuria
Repeat to confirm persistently abnormal result. If known microalbuminuria keep testing to ensure levels are not rising Proteinuria
Repeat to confirm persistently abnormal result. If known proteinuria keep testing to ensure levels are not rising Management of Diabetic Renal Disease
Prevention:
•
Good blood glucose control (HbA1c <7% or 53 mmol/mol), good blood pressure control (BP <130/80mmHg)
Treatment:
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Target BP for all patients with diabetes under GMS is 145/85. SIGN recommends 130/80mmHg but once the ACR becomes elevated then this target should be as low as possible. However, targets may need to be higher in high risk groups of patients particularly those with ischaemic heart disease. Introduce an ACE Inhibitor in patients with Type 1 diabetes with microalbuminuria or overt proteinuria, regardless of BP (unless symptomatic hypotension). Use highest tolerated doses. In those intolerant use angiotensin receptor blocker (ARB). Remember the possibility of teratogenesis in females of childbearing age. Introduce an ACE Inhibitor in patients with Type 2 diabetes. Remember the possibility of co-existing renovascular disease especially in those with intermittent claudication. In those intolerant use ARB. In all patients, co-existing cardiovascular risk factors should be managed aggressively. Refer to dietitian for dietary assessment and advice in relation to protein and sodium intake

Criteria for Referral to Hospital Diabetes Clinic:
Patients with any of the following:
•
Proteinuria (Total urinary protein >1 g/l, protein:creatinine ratio (PCR) > 100 mg/mmol) Elevated serum creatinine or eGFR < 30 ml/min/1.73m2

Criteria for Referral to Renal Clinic:
• Nephropathy that is out of keeping with diabetic history (short duration, lack of other complications etc )

eGFR and Diabetes:

Website

A range of information is available on the RIE Renal unit website http://www.edren.org/
Email Advice

Should you have a concern or question about renal function and diabetes, there is an email advice line (also
available through Refhelp). This is very useful for getting informal advice about patients and their treatment
that may avoid unnecessary referral or anxiety.
Metformin treatment and renal impairment

There has always been concern about the use of Metformin in renal failure (previous advice gave a threshold
of a creatinine of greater than 150mmol/l for stopping metformin). It is clear that worsening renal function
increases the risk of lactic acidosis with Metformin use. The risk increases as eGFR deteriorates.

Once the eGFR falls below 30 ml/min, Metformin must not be used.

Between 30 and 60 ml/min Metformin can be used with caution. There is no immediate need for action
provided the patient is well. However acute lactic acidosis does occur in patients’ whose eGFR is in the
range 30-45 when they develop what would have been a trivial illness (such as diarrhoea and vomiting)
which compromises renal function and causes acute renal failure. This is compounded if the patient is also
taking diuretics and/or ACE inhibitors and/or non-steroidal anti-inflammatory drugs (NSAIDs) in combination
with Metformin. Unlike acute illnesses in type 1 diabetes (where insulin treatment must be continued)
stopping any of the above cocktail of drugs for a day or two during an acute dehydrating (diarrhoea &
vomiting) illness will not cause any immediate problem for the patient and will help protect renal function until
the patient improves. Blood glucose measurements should be used to assess any glycaemic deterioration.
Microalbuminuria Screening in People with Diabetes
Early morning urine specimen for albumin:creatinine ratio (ACR) A random sample may be used but the early morning sample is preferable as there are fewer false positive results is the ratio >2.5 men
or >3.5 women
Other causes?
Screening Internal:
Annual Screening
What to do:
Input ACR values and record the diagnosis Consider ACE inhibitor or ARB (Angiotensin NB consider referral if BP targets are not met,
progressive increase in ACR or elevated
creatinine due to other diseases

Source: http://www.nhslothian.scot.nhs.uk/Services/A-Z/DiabetesService/InformationHealthProfessionals/DiabetesHandbookForPrimaryCare/Kidney%20Complications.pdf