Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (560 page)

D, decreased; GFR, glomerular filtration rate; I, increased; N, normal; sl, slightly.
*when albuminuria is 0.075–0.1 g/d in IDDM, significant renal disease is present and albuminuria will progress to clinical nephropathy. GFR declines—10 mL/min/y after nephropathy is established.
Source: Selby JV, Fitz-Simmons SC, Newman M, et al. The natural history and epidemiology of diabetic nephropathy.
JAMA.
1990;263:1954–1960.

   Who Should Be Suspected?

   Diabetes and DN are more prevalent in blacks, Mexican Americans, Polynesians, and Maoris. Additional risk factors include poorly controlled diabetes, positive family history, and uncontrolled hypertension.

   Generally, any patient presenting with progressive renal failure or proteinuria should be investigated for the presence of DM. On the other hand, all patients with DM should have urinalysis and renal function studies performed periodically.

   Laboratory Findings

   Microalbuminuria (urinary albumin excretion between 30 and 300 mg/day, or 30–300 mg/g creatinine using a random urine sample) usually appears 5–10 years after the onset of diabetes. Macroalbuminuria, also referred to as clinical albuminuria (>300 mg/g creatinine), can occur at later stages and may in some cases develop to frank nephrotic syndrome. An elevated albumin/creatinine ratio should be confirmed with an additional first-void urine specimen collected in the next 3–6 months (see Figure
12-4
).

   Urine sediment is usually bland, but hematuria may rarely occur.

   Serum protein may be decreased, especially in the advanced disease.

   BUN and creatinine rise gradually; azotemia usually develops several years after the onset of proteinuria.

   Measurement of hemoglobin A1c (HbA1c) in DM patients and maintaining it at a target value of approximately 7.0% helps prevent or delay progression of DN.

Figure 12–4
Screening for microalbuminuria.
Source: American Diabetes Association. Nephropathy in diabetes.
Diabetes Care
. 2004 Jan;27 Suppl 1:S79–83.

Suggested Readings

DOQI clinical practice guidelines and clinical practice recommendations for diabetes and chronic kidney disease.
Am J Kidney Dis.
2007;49(2 Suppl 2):S12–S154.
http://www.kidney.org/professionals/kdoqi/pdf/Diabetes_AJKD_FebSuppl_07.pdf

KDOQI clinical practice guideline for diabetes and CKD: 2012 update.
Am J Kidney Dis.
2012;60(5):850–886.
http://www.kidney.org/professionals/KDOQI/guidelines_diabetesUp/diabetes-ckd-update-2012.pdf

HENOCH-SCHÖNLEIN PURPURA NEPHRITIS

   Overview

   See Henoch
-
Schönlein purpura (HSP).