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Hyperglycinuria: diagnosis in middle age
  1. Hithem Fargaly1,2,
  2. Shobi Mathew3 and
  3. Noreen F Rossi1
  1. 1Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA
  2. 2Internal Medicine, Detroit Medical Center, Detroit, Michigan, USA
  3. 3Wayne State University School of Medicine, Detroit, Michigan, USA
  1. Correspondence to Dr Noreen F Rossi; nrossi{at}


Isolated hyperglycinuria is a rare disorder that is associated with osteoporosis and renal calculi. We report findings in a middle-aged, black woman who presented for renal function evaluation with a history of transient hypobicarbonataemia associated with topiramate therapy. She displayed the full triad of high urinary glycine, early-onset osteopenia despite normal reproductive hormones, and renal calculus with high urinary oxalate, phosphate and uric acid. Parathyroid hormone and fibroblast growth factor 23 were both normal. Formal genetic testing did not reveal mutations in SLC6A20, SLC6A18, SLC6A19, SLC36A2, the known genes associated with glycinuria; however, black individuals are poorly represented in the genetic databases. It may well be that otherwise unidentified mutations may be present or that topiramate may result in a lingering proximal tubule defect even after cessation of the drug.

  • fluid electrolyte and acid-base disturbances
  • osteoporosis
  • renal medicine

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  • Contributors HF compiled the clinical and laboratory data and wrote the original draft. SM researched the literature for the background and discussion and contributed to the initial draft. He also worked on the response to the reviewers. NFR cared for the patient, supervised the organisation of the clinical and laboratory data, literature search and edited the final draft, responses and revision of the case report.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.