Differentials
Nondiabetic kidney disease
SIGNS / SYMPTOMS
Since both diabetes mellitus and chronic kidney disease are common disorders, patients with both conditions may or may not have DKD.[59]
A diagnosis other than DKD should be considered if: there is a rapid progression of renal failure, evidence of another systemic disease, or short duration of diabetes (although onset is insidious in type 2, and DKD may occasionally be the presenting manifestation). Concurrent chronic medical conditions and unresolved acute tubular necrosis are common contributory factors.
INVESTIGATIONS
Minimal proteinuria may indicate nondiabetic kidney disease.
Other specific diagnostic tests for other systemic disorders associated with nondiabetic kidney disease may be positive (e.g., serum protein electrophoresis or serum free light chains in myeloma, antinuclear antibodies in systemic lupus erythematosus [SLE], antineutrophil cytoplasmic antibody in vasculitis, hypocomplementemia in SLE, cryoglobulinemia).
Multiple myeloma
SIGNS / SYMPTOMS
Patients with multiple myeloma (MM) may present with renal failure and proteinuria.[60]
Bone pain and anemia are common presenting features.[60]
INVESTIGATIONS
Characteristic test results that differ from DKD are: the presence of paraproteinemia/paraproteinuria; hypercalcemia; impaired production of normal immunoglobulin; and lytic bone lesions.[60]
Urinalysis with sulfosalicylic acid (SSA) was classically utilized to evaluate for discrepancy between albumin and total protein, as standard urinalysis dipstick detects albumin only. SSA causes precipitation of all of the urinary proteins, including paraproteins (Bence Jones proteins).
Serum protein electrophoresis (SPEP), urine protein electrophoresis (UPEP): paraprotein spike.
Serum and urine free light chains: increased concentrations of free light chain in serum and urine.
Skull x-rays, CT, or MRI bone: lytic lesions.
Bone marrow biopsy: plasma cell proliferation.
Renal tract obstruction
SIGNS / SYMPTOMS
Can be caused by stones, cancer, fibrosis, prostate hypertrophy/cancer, neurogenic bladder, or pelviureteric junction obstruction.
Obstruction to urine flow can result in postrenal failure. Symptoms include trouble passing urine, anuria, oliguria, hematuria, pain (with kidney stones), and urinary leakage/incontinence.
Physical examination findings include enlarged prostate on rectal examination, costovertebral angle tenderness, suprapubic tenderness, and bladder fullness.
INVESTIGATIONS
Passage of Foley catheter may result in flow of urine and relief of obstruction.
Kidney ultrasound: hydronephrosis, stones.
Prostate ultrasound: hypertrophy, cancer.
CT abdomen: hydronephrosis, stones, mass, congenital abnormalities, fibrosis.
Prostate specific antigen: elevated in benign prostatic hyperplasia, prostate cancer.
MRI: not routine but may show hydronephrosis, stones, mass, congenital abnormalities, fibrosis.
Glomerulonephritis
SIGNS / SYMPTOMS
Glomerulonephritis, such as lupus nephritis and cryoglobulinemia, is in the differential for DKD.
Patient presentation and physical examination may be similar to that of DKD. However, there may be symptoms and signs of other systemic disease, such as rashes or joint involvement.
INVESTIGATIONS
Urinalysis: hematuria, proteinuria, red blood cell casts, dysmorphic red cells.
Albuminuria.
Positive serology (e.g., antinuclear antibodies, antineutrophil cytoplasmic antibodies, hepatitis serology).
Complement: decreased in immune glomerulonephritis (e.g., lupus).
Kidney biopsy: glomerulonephritis.
Renal artery stenosis
SIGNS / SYMPTOMS
Renal artery stenosis presents either as hypertension refractory to multiple maximized antihypertensives or as renal failure shortly after the initiation of an ACE inhibitor or angiotensin-II receptor antagonists.
Physical examination is significant for an abdominal bruit.[61]
INVESTIGATIONS
Ultrasound, CT scan, MRI: shrunken kidney, decreased flow through the renal artery.
Magnetic resonance angiography: renal artery stenosis.
Renal angiogram: renal artery stenosis.
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