Analysis of five cases showing false-high Hemoglobin A1c due to reduced catalase activity.

We encountered five cases that exhibited false-high Hemoglobin A1c (HbA1c) levels when samples were examined using the enzyme-based NORUDIA N HbA1c kit. HbA1c levels were higher than those obtained using other methods, such as HPLC, immune-based methods, and other enzyme-based kits. This kit produced inaccurate results for HbA1c when residual peroxides were present in samples. The addition of peroxidase solution restored false-high HbA1c levels in the five cases, indicating that reduced catalase activity was responsible for these values because catalase eliminates peroxide. Catalase activity and gene mutations were examined in the five cases and an immunohistological analysis was performed to assess the expression of catalase. Cases #1 and 2 were diagnosed as acatalasemia and cases #3, 4, and 5 as hypocatalasemia based on compound heterozygous SNP and heterozygous splicing mutations in the catalase gene. Therefore, impaired catalase activity was responsible for false-high HbA1c levels measured by the NORUDIA N HbA1c kit.

Severe Non-Islet Cell Hypoglycemia From Ileum-Origin Gastrointestinal Stromal Tumor Producing Insulin-Like Growth Factor-2 in a Patient With Liver Cirrhosis Due to Chronic Hepatitis B.

Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome, and NICTH associated with gastrointestinal stromal tumor (GIST) is even more rare. Herein, we describe a patient with severe NICTH due to GIST who had developed liver cirrhosis as a consequence of chronic hepatitis B. Although circulating insulin, C-peptide, and insulin-like growth factor-1 (IGF-1) levels were significantly decreased, in contrast to our expectations, the growth hormone (GH) level was slightly elevated. Steroid therapy with prednisolone appeared to be effective for the prevention of severe and continuous hypoglycemia.

Hb Phnom Penh Showing Falsely High or Reasonable HbA1c Values Depending on the Type of High-performance Liquid Chromatography System.

We herein report a 50-year-old Chinese woman with Hb Phnom Penh (α117Phe-Ile-α118Thr) showing high or reasonable HbA1c values depending on the type of high-performance liquid chromatography (HPLC) system. A high HbA1c value of 7.5% (HPLC assay: G9) and a reasonable HbA1c value of 5.2% (assay unknown) were observed. Therefore, the patient was refereed to our hospital; the oral glucose tolerance test showed normal glucose tolerance. The HbA1c values measured by an enzymatic assay, immunoassay, and affinity assay, as well as most HPLC assays were within the reference range, whereas those measured by the Tosoh HPLC systems were high.

Isolated Adrenocorticotropic Hormone Deficiency and Severe Hypercalcemia After Destructive Thyroiditis in a Patient on Nivolumab Therapy With a Malignant Melanoma.

We describe a 58-year-old man with a malignant melanoma metastasis to the liver. After initiation of nivolumab therapy, he developed destructive thyroiditis and subsequently simultaneous isolated adrenocorticotropic hormone (ACTH) deficiency and severe hypercalcemia. Although isolated ACTH deficiency and hypercalcemia due to nivolumab therapy are both rare occurrences, these conditions can often cause a severe clinical course accompanied by a disturbance of consciousness. Therefore, clinicians should pay attention to these possible side effects of nivolumab if the patients have clinical symptoms, such as fatigue and a disturbance of consciousness.