Diabetes: Nephropathy

Related Subjects: Type 1 DM | Type 2 DM | Diabetes in Pregnancy | HbA1c | Diabetic Ketoacidosis (DKA) Adults | Hyperglycaemic Hyperosmolar State (HHS) | Diabetic Nephropathy | Diabetic Retinopathy | Diabetic Neuropathy | Diabetic Amyotrophy | Maturity Onset Diabetes of the Young (MODY) | Diabetes: Complications | Analgesic Nephropathy IgA Nephropathy (Berger's disease) HIV associated nephropathy (HIVAN) Balkan endemic nephropathy (BEN)

There is a nodular diabetic glomerulosclerosis with thickening of basement membranes, mesangial expansion and a Kimmelstiel–Wilson lesion which is pathognomonic of diabetic kidney disease.

About

• A complication of T1/2 Diabetes. 60% of TIDM over 30 years
• First signs: increased renal size/perfusion and microalbuminuria (30-300 mg/24 hrs)
• Hypertension accelerates renal damage

Effects

• Glomerular sclerosis
• Renal Papillary necrosis
• Chronic kidney disease
• Recurrent UTIs
• Arteriolar disease
• Hyporeninaemic hypoaldosteronism (raised potassium)

The following may suggest that worsening renal function is not due to diabetes

• Lack of retinopathy
• There is persistent haematuria or red cell casts
• Lack of micro or macro albuminuria
• Rapid deterioration

Microalbuminuria is when urine dipstick is positive for protein but the urine albumin:creatinine ratio (UA:CR) is > 3mg/mmol

Investigations

• Send an early morning urine sample. Microalbuminuria if UA:CR > 3 mg/mmol.
• UA:CR > 30 mg/mmol is consistent with overt nephropathy
• U&E with serum creatinine to calculate the estimated GFR.
• Diagnose CKD and manage appropriately. If the eGFR < 60 mL/min/1.73 m2 for 3 months or more, and/or Persistent proteinuria with urine ACRn > 3 mg/mmol, for 3 months or more.

Pathology

• Kimmelstiel-Wilson lesion
• Nodular glomerulosclerosis
• Thickened GBM and Mesangial expansion

Steps in renal damage

• Hyperfiltration, Microalbuminuria
• Proteinuria, Falling GFR and ESRF

Management of CKD

• Screening identifies nephropathy in type 1/2 diabetes
• Classify the stage of CKD.
• Arrange monitoring/management, depending on the severity.
• Stop smoking, optimize blood glucose control with Hba1C
• Optimise lipid levels - Atorvastatin 20 mg OD
• BP control: ACEI/ARBs +/- Diuretic
• Refer Nephrology if UA:CR >7 ± GFR falling by >5mL/min/1.73m2/yr
• Renal replacement therapy: worsening GFR/Fluid overload/symptomatic uraemia.
• Renal transplantation: improves quality of life. Unusual for diabetic nephropathy to develop in the allograft.
• Pancreatic transplantation (with renal transplantation) can produce insulin independence and delay or reverse microvascular disease
• Ensure the person is aware of the 'sick-day rules' and which medications, if any, to temporarily stop if there is intercurrent illness or dehydration, to reduce the risk of acute kidney injury (AKI).

References

• Diabetic complications