RESUMO
Dent's disease is a rare X-linked condition caused by a mutation in CLCN5 and OCRL gene, which impair the megalin-cubilin receptor-mediated endocytosis in kidney's proximal tubules. Thus, it may manifest as nephrotic-range low-molecular-weight proteinuria (LMWP). On the other hand, glomerular proteinuria, hypoalbuminemia, and edema formation are the key features of nephrotic syndrome that rarely found in Dent's disease. Here, we reported a man in his 30 s with Dent's disease presented with leg edema for 5 days. The laboratory results revealed hypoalbuminemia and a decrease of urine ß2-microglobulin/urine protein ratio (Uß2-MG /UP), indicating that the primary origin of proteinuria shifted from LMWP to glomerular proteins. The kidney biopsy revealed glomerular abnormality and calcium deposition in the renal medulla. Electron microscopy of the kidney tissue indicated extensive foot-process effacement of the glomerular podocytes and degeneration of tubular epithelium. After a combination of treatment with prednisolone and cyclosporine (CyA), the nephrotic syndrome was remitted. Given the atypical clinical presentation and the shift of LMWP to glomerular proteinuria in this patient, glomerulopathy and the Dent's disease existed separately in this patient.
Assuntos
Doença de Dent/diagnóstico , Glomérulos Renais/ultraestrutura , Túbulos Renais Proximais/metabolismo , Síndrome Nefrótica/diagnóstico , Adulto , Biópsia , Calcinose/diagnóstico , Ciclosporina/uso terapêutico , Doença de Dent/complicações , Doença de Dent/etiologia , Doença de Dent/genética , Quimioterapia Combinada , Glucocorticoides/uso terapêutico , Humanos , Hipoalbuminemia/etiologia , Imunossupressores/uso terapêutico , Rim/patologia , Glomérulos Renais/anormalidades , Glomérulos Renais/patologia , Túbulos Renais Proximais/patologia , Masculino , Microscopia Eletrônica/métodos , Síndrome Nefrótica/sangue , Síndrome Nefrótica/tratamento farmacológico , Síndrome Nefrótica/urina , Prednisolona/uso terapêutico , Proteinúria/diagnóstico , Proteinúria/etiologia , Resultado do TratamentoRESUMO
Serum level of phosphate is regulated by the kidney, especially proximal tubule. The transcellular transport of phosphate in the proximal tubule is mediated via Na dependent transporters, i.e., NPT2a and NPT2b at the luminal membrane, and unknown channel at the basolateral side. The transport of phosphate via NPT2a and NPT2b is further regulated by factors, such as PTH, FGF23, and 1,25(OH)(2)D. Several hereditary diseases that cause hypophoshatemia specically are known. In addition, dysfunction of proximal tubule may develop Fanconi syndrome, which also causes hypherphosphaturia. In this section, I describe the renal mechanisms of phosphate handling and the causes of hypophosphatemia along with its treatment.