title: Rare case of nephrocalcinosis in the distal tubules caused by hereditary renal hypouricaemia 3 months after kidney transplantation.
abstract: We report a rare case of nephrocalcinosis caused by hereditary renal hypouricaemia 3 months after kidney transplantation. A 41-year-old man who underwent living-related kidney transplantation from his father was admitted to our hospital for a protocol biopsy; he had a serum creatinine (S-Cr) of 1.37 mg/dL and no proteinuria. Histologically, there was no evidence of rejection or calcineurin inhibitor toxicity, although scattered nephrocalcinosis was observed in the distal tubules. Perioperatively, the patient had a serum uric acid (S-UA) of 1.9 mg/dL with a fractional excretion of uric acid (FEUA) of 29% (normal, <10%) and UA clearance of 26.8 mL/min (normal, 7.3-14.7 mL/min) 3 days after kidney transplantation. The donor also had a relatively low S-UA of 2.4 mg/dL and high FEUA of 10.3%. Subsequent DNA direct sequencing followed by restriction fragment length polymorphism revealed that both the recipient's and donor's urate transporter 1 (URAT1) gene had a heterozygous nonsense mutation in exon 5 (C889T). Further, the immunoreactivity of antibodies for the C terminus of URAT1 revealed a partial deletion. De Galantha and von Kossa staining revealed that the nephrocalcinosis was due to urate crystals and calcium stones. Therefore, we diagnosed hereditary renal hypouricaemia. We directed the patient to avoid hard exercise, drink plenty of water, and alkalize the urine. The 1-year follow-up allograft biopsy showed no evidence of nephrocalcinosis in the distal tubules. This is the first report of nephrocalcinosis in the distal tubules as a diagnostic clue to hereditary renal hypouricaemia. We also review the related literature.
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Okabayashi
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Izumi
authors.initials: I
authors.lastname: Yamamoto
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Yo
authors.initials: Y
authors.lastname: Komatsuzaki
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Takahito
authors.initials: T
authors.lastname: Niikura
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamakawa
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Haruki
authors.initials: H
authors.lastname: Katsumata
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Kawabe
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Ai
authors.initials: A
authors.lastname: Katsuma
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nakada
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Akimitsu
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Department of Urology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Koike
authors.affiliation: Department of Urology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Miki
authors.affiliation: Department of Urology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Yudo
authors.initials: Y
authors.lastname: Tanno
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Ohkido
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tsuboi
authors.affiliation: Department of Pathophysiology, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
authors.forename: Kimiyoshi
authors.initials: K
authors.lastname: Ichida
authors.affiliation: Department of Internal Medicine, Atsugi City Hospital, Kanagawa, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokoo
mesh_terms: D000328:Adult; D064591:Allografts; D001706:Biopsy; D018389:Codon, Nonsense; D005091:Exons; D005220:Fathers; D020022:Genetic Predisposition to Disease; D040941:Heredity; D006579:Heterozygote; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D007686:Kidney Tubules, Distal / Q000473:pathology*; D019520:Living Donors; D008297:Male; D009397:Nephrocalcinosis / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D027361:Organic Anion Transporters / Q000235:genetics; D027701:Organic Cation Transport Proteins / Q000235:genetics; D010641:Phenotype; D015499:Renal Tubular Transport, Inborn Errors / Q000150:complications* / Q000175:diagnosis / Q000235:genetics / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome; D014545:Urinary Calculi / Q000150:complications* / Q000175:diagnosis / Q000235:genetics / Q000628:therapy
chemical_list: D018389:Codon, Nonsense; D027361:Organic Anion Transporters; D027701:Organic Cation Transport Proteins; C491241:SLC22A12 protein, human
keywords: URAT1; hereditary renal hypouricaemia; kidney transplantation; nephrocalcinosis; renal biopsy