Urinary ß2-microglobulin as an early marker of infantile enterovirus and human parechovirus infections.

Enterovirus and human parechovirus (HPeV) are RNA viruses belonging to the family Picornaviridae that frequently infect infants. These infections show a wide variety of clinical manifestations, from mild to severe. However, there are no known early clinical markers for diagnosis and prediction of disease severity. The aim of this study was to examine the clinical utility of urinary beta 2-microglobulin (ß2MG) for the early detection and prognosis of infantile enterovirus and HPeV infections.This retrospective study included 108 full-term infants younger than 60 days of age, including 15 with enterovirus or HPeV-3 (enterovirus/HPeV-3), 22 with respiratory syncytial virus (RSV), and 24 with bacterial infections. Laboratory data and clinical characteristics were compared among these 3 groups. Of the 15 patients with enterovirus/HPeV-3, 6 were treated with intravenous immunoglobulin (IVIG subgroup) because of severe clinical conditions.Urinary ß2MG to creatinine ratio (ß2MG/Cr) was significantly higher in the enterovirus/HPeV-3 group compared to bacterial and RSV infection groups (both P < .001). In the enterovirus/HPeV-3 group, mean peak urinary ß2MG/Cr was observed on day 1 or 2. Urinary ß2MG/Cr values were significantly higher in the IVIG subgroup than the non-IVIG subgroup (P < .001).Increased urinary ß2MG/Cr in early-stage infection may be a useful clinical marker for the detection and prediction of infantile enterovirus and HPeV infection severity.

Serum calcitriol levels in a patient with X-linked hypophosphatemia complicated by autosomal dominant polycystic kidney disease.

Serum calcitriol [1,25(OH)2D] levels are low normal in the presence of hypophosphatemia in X-linked dominant hypophosphatemic rickets (XLH) due to elevated serum fibroblast growth factor 23 (FGF23) levels. We report a peculiar finding of markedly elevated serum 1,25(OH)2D levels in a patient with XLH complicated by autosomal dominant polycystic kidney disease (ADPKD) and retinitis pigmentosa (RP). She was diagnosed with XLH, ADPKD and RP at the age of 5, 13 and 15 years, respectively. After the diagnosis of ADPKD, the 1,25(OH)2D levels increased up to 282 pg/mL treated with a pharmacological dose of 1αOHD3 (1αOHD3). At the age of 17 years, under a physiological dose, serum 25-hydroxyvitamin D3 (25OHD3) and 1,25(OH)2D levels were 14.0 ng/mL and 93 pg/mL, respectively. With off-therapy for 3 days, the latter decreased to 9 pg/mL with an increased ratio of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3)/25OHD3. Serum FGF23 and circulating soluble α-klotho (sKlotho) levels were 552 and 873 pg/mL, respectively, with the latter being almost half of the normal control. Since the coexistence of elevated serum FGF23 and 1,25(OH)2D levels contradicted the conventional FGF23 actions, we speculated on the possible association of decreased sKlotho with the peculiar vitamin D metabolism, although mechanisms in detail remained unknown.