How is minimal-change disease (MCD) diagnosed?

Updated: Jan 05, 2021
  • Author: Abeera Mansur, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Urinalysis findings are benign in minimal-change disease (MCD), but profound proteinuria and oval fat bodies may be observed. In children, the critical level for diagnosis is proteinuria of more than 40 mg/h/m2. In adults, the threshold is more than 3.5 g/d/1.73 m2.

A random albumin-to-creatinine concentration ratio is in excess of 5. Urine specific gravity is high because of proteinuria. A 24-hour urine measurement should be obtained for protein and creatinine clearance.

Hypoalbuminemia is an important marker of nephrotic syndrome. The level at which edema occurs varies, but it tends to be lower in children than in adults. Nephrotic syndrome in children is defined by a serum albumin of less than 2.5 g/dL. Hyperlipidemia also is a feature of a nephrotic state.

Other laboratory findings are as follows:

  • Kidney function usually is normal except in cases of undiagnosed focal segmental glomerulosclerosis (FSGS) or in those cases that progress to acute kidney injury

  • Serologic workup (including antinuclear antibodiescomplements, and cryoglobulins) is normal

  • Hyponatremia is often observed and is in part a spurious finding secondary to the hyperlipidemic state; it also occurs from water retention caused by hypovolemia and antidiuretic hormone release

  • Elevated hemoglobin and hematocrit are consequences of plasma volume contraction

Renal sonogram results are normal in patients with MCD.

Because MCD accounts for 90% of all cases of idiopathic nephrotic syndrome in children, kidney biopsy is not part of the initial workup for MCD in that age group. Instead, biopsy is performed only in those children who fail to achieve remission with an empiric course of corticosteroids. In contrast, a kidney biopsy is performed in all adult patients with nephrotic syndrome, before the initiation of treatment for MCD.


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