Efficacy of zinc monotherapy in a Wilson’s disease adolescent with unusual renal onset: a case report and review of literature

BACKGROUND: Wilson’s disease (WD) is a rare genetic disorder of copper metabolism that typically presents with hepatic, ophthalmologic, neurological, or psychiatric symptoms. Signs of renal involvement usually do not dominate the initial clinical picture of WD. For this category of patients affected by WD, there is no clear indication for first-line treatment nor on which parameters to evaluate therapeutic efficacy. CASE PRESENTATION: A 17-year-old patient was referred to our clinic because of lower back pain and gross haematuria. The laboratory exams showed kidney function decline and renal proximal tubular dysfunction, likely due to Fanconi syndrome. Abdominal ultrasound revealed bilateral renal microlithiasis, hepatosplenomegaly and a multinodular hepatic echotexture despite normal liver enzyme levels. A thorough investigation ruled out infectious, autoimmune, neoplastic and haematological disorders. WD was suspected based on kidney injury complicated by Fanconi syndrome combined to signs of chronic liver disease. Serum ceruloplasmin was undetectable, and 24 h-urinary copper excretion was markedly elevated. Slit-lamp examination identified bilateral Kayser–Fleischer rings, and brain MRI revealed classical WD changes with only clinical evidence of mild hypomimia. The diagnosis of WD was genetically confirmed. Monotherapy with zinc acetate resulted in improvement in renal function and hypomimia and a reduction in urinary copper excretion over a 2-year follow-up period. From a hepatic and ophthalmological point of view, the patient remained stable with no signs of progression. Starting from the peculiarities of this case, a literature review was performed focusing on cases of WD with renal manifestations at onset and the behaviour of Kayser–Fleischer rings following pharmacological therapy. CONCLUSIONS: A high index of clinical suspicion for WD is recommended in adolescents with unexplained renal impairment, including Fanconi syndrome, even in the absence of abnormal liver tests. A critical assessment of the patient’s outcome, based on the integration of multiple clinical, laboratory, and imaging parameters, showed that zinc monotherapy may represent a safe and effective first-line treatment in these patients.