Medical Professional Publications

A “Diagnostic Dilemma” in Severe Post-Strep Glomerulonephritis

Columbus, OH — May 2017

In the last several years, members of the Section of Nephrology at Nationwide Children’s Hospital have seen presentations of poststreptoccal glomerulonephritis (PSGN) that don’t appear in medical literature. Some patients hospitalized for PSGN had thrombocytopenia and positive tests for antinuclear antibodies (ANA) and/or cytoplasmic anti-neutrophil cytoplasmic antibodies. Some needed renal replacement therapy.

In fact, these patients with atypical PSGN could be mistaken for patients with lupus nephritis — and that mistake could lead to unwarranted treatment.

Physician-researchers at Nationwide Children’s recently published a case series in the International Journal of Nephrology documenting these atypical presentations of severe PSGN, in part to start a conversation about what may be leading to them.

“We had never seen this phenotype before,” says Rose Ayoob, MD, attending pediatric nephrologist at Nationwide Children’s, medical director of the hospital’s Dialysis Program and lead author of the publication. “Other institutions have seen severe courses like the ones we have seen, so severe that patients needed dialysis. By itself, that is unusual for this disease. At the time of those other reports, though, institutions had not looked for ANA or thrombocytopenia.”

“First, we wanted to note this phenotype. But we have a continuing question about whether certain serotypes of group A Streptococcus may result in a more severe clinical picture, and other institutions that have seen severe PSGN may also be interested in this.”

The publication analyzed 17 pediatric patients seen over a one-year period who were diagnosed with acute PSGN. A total of 13 patients were hospitalized, and four underwent biopsy because of concern over rapidly progressive glomerulonephritis. Three had positive ANA tests and required dialysis. Two of those with positive ANA tests also had thrombocytopenia. The one patient without a positive ANA test had a positive c-ANCA test.

Some of those lab results may lead to a “diagnostic dilemma,” in the words of the authors, since they can point to an underlying autoimmune or vasculitic issue.

“If you see thrombocytopenia, you naturally go looking for an angiopathic process, for other causes, especially with positive antibody tests. Strep can present like this, though,” says Dr. Ayoob. “If a biopsy shows a post-infectious cause, and patients do better with supportive care and dialysis, then there is not a reason to be more aggressive with therapy.”

Due diligence with a differential diagnosis is crucial with these patients, Dr. Ayoob says. The atypical patients in the recent study all had complement component 3 levels improve at follow-up, and none of them showed kidney disease progression.

Dr. Ayoob and her colleagues have continued to document severe, atypical PSGN and plan to conduct other research on the subject.         

Reference:
Ayoob RM, Schwaderer AL. Acute kidney injury and atypical features during pediatric poststreptococcal glomerulonephritis. International Journal of Nephrology. 2016 Aug 23. [Epub ahead of print]

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