Tests
1st tests to order
urinalysis
Test
Typical results show 3+ to 4+ proteinuria on dipstick.[3]
Urine sediment in idiopathic nephrotic syndrome is usually benign except for occasional hyaline casts and oval bodies. Other types of cellular casts are uncommon.
Microcopic hematuria may be present in a minority of patients. In the International Study of Kidney Disease in Children, hematuria was seen in 23% of patients with minimal change disease.[20]
Result
protein: 3+ to 4+; no significant hematuria
24-hour urine protein
Test
May be difficult to collect 24-hour urine in a younger child; urine protein/creatinine ratio in a spot sample is an alternative test.
Result
≥1000 mg/square meter of body surface area/day
urine protein/creatinine ratio
Test
Easier and more reliable alternative to 24-hour urine protein in a younger child.
Nephrotic-range proteinuria can vary by age and size of child. For example, a ratio of 1 (about 1 g/24 hours) in a 20 kg patient may signify nephrotic-range proteinuria. In an adolescent patient, a ratio of 1 represents mild to moderate proteinuria.[4][20]
Result
>2 mg/mg
serum albumin level
Test
Hypoalbuminemia is a hallmark of nephrotic syndrome. In minimal change disease, serum albumin can be as low as 1 g/dL.
Result
typically <3 g/dL
serum lipid profile
Test
Massive hyperlipidemia is common due to overcompensation by the liver and is a hallmark of nephrotic syndrome.
Serum albumin level and total cholesterol level are inversely related: the lower the serum albumin level, the higher the cholesterol level.
Result
elevated triglyceride and cholesterol
serum complement levels
Test
Normal in typical idiopathic nephrotic syndrome (minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy).
C3 levels are low in membranoproliferative glomerulonephritis, postinfectious glomerulonephritis, and systemic lupus erythematosus.
If C3 level is low, additional tests should be performed to differentiate these conditions, including antinuclear antibody, anti-double-stranded DNA antibody, antistreptolysin O antibody, anti-DNase antibody, and CH50 levels.
Result
normal C3 and C4
serum electrolyte panel
Test
Serum creatinine is normal, although BUN may be slightly elevated in volume-contracted states. Serum sodium level may be low partly due to depressed free water excretion (volume contraction may stimulate ADH secretion) or partly due to hyperlipidemia (pseudohyponatremia).
Result
normal or slightly elevated BUN, decreased sodium level
CBC
Test
The Hb level and hematocrit may be elevated in nephrotic syndrome if the patient is volume contracted. The platelet count may also be elevated.
Result
increased Hb and hematocrit, increased platelet count
GFR
Test
Determined by mathematical equations such as Cockcroft-Gault, CKiD U25, or the Modification of Diet in Renal Disease Formula, the GFR determines the severity and stage of chronic kidney disease. [ Glomerular Filtration Rate Estimate by the IDMS-Traceable MDRD Study Equation Opens in new window ] [ Glomerular filtration rate estimation (eGFR) by CKiD U25 equations with creatinine and/or cystatin C in children and adults ≤25 years old Opens in new window ]
Result
normal
serum LFTs
Test
Necessary, as elevated serum aspartate aminotransferase and alanine aminotransferase levels may suggest underlying hepatitis. If they are elevated, an acute hepatitis profile should be obtained to include hepatitis B and C studies.
Result
normal
kidney ultrasound
Test
Helps to confirm the presence of two kidneys, and assesses their size and structure.[2]
In nephrotic syndrome, the kidneys typically appear normal. In some patients with severe edema, the kidneys may be echogenic and show loss of corticomedullary differentiation. Kidneys may also be enlarged.
Result
normal
Tests to consider
CXR
Test
Indicated in patients with respiratory symptoms to exclude pneumonia or pleural effusion, which can occur as a complication of nephrotic syndrome. CXR should also be obtained in cases of suspected minimal change disease associated with lymphoma.[2] In some countries where tuberculosis is endemic, it is a routine practice to obtain CXR before initiation of corticosteroid therapy to rule out tuberculosis.
Result
normal unless complications are present (infiltrates suggesting pneumonia or pleural effusion)
kidney biopsy
Test
Electron microscopy is diagnostic.
Usually reserved for children who do not respond to corticosteroids, have atypical presentations (such as persistently elevated serum creatinine, significant hematuria, etc.) and relapse frequently despite corticosteroid-sparing therapy.
Should also be considered in children when factors at presentation suggest histology other than minimal change disease (MCD), as treatment may differ. For example, MCD is uncommon in infants ages <1 year; congenital (Finnish type) nephrotic syndrome or focal segmental glomerulosclerosis is more likely.
In adults, a kidney biopsy is required for diagnosis of MCD and it should be considered for children ages ≥12 years.[2][3]
Result
normal by light microscopy, but podocyte effacement on electron microscopy
genetic testing
Test
Infants ages <1 year may undergo genetic testing instead of or in addition to kidney biopsy.[2]
Result
may be positive for a mutation associated with minimal change disease
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